ML19270G019

Power Transfer,How & Why

ML19270G019
Person / Time
Site:	Crane
Issue date:	03/29/1979
From:	Strang W, Wyatt M BECKWITH ELECTRIC CO., INC.
To:
Shared Package
ML19241A582	List: ML19241A580 ML19270G019
References
NUDOCS 7904170103
Download: ML19270G019 (56)

Text

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POWER TRANSFER H 0 if AND WHY MICHAEL A. WYATT WILLIAM M.

STRANG BECKWITH ELECTRIC CO.,

INC.

11811 62ND STREET NORTH LARGO, FLORIDA 33543 7904170lo 3 29 117

r ABSTRACT A review of the current general methods of transfer of generating plant auxiliary systems between primary and alternate power sources identifies the requirement for a high speed device to verify synchronism during the power transfer sequence. Two devices are presented - the Beckwith Electric M-0236 Power Transfer Relay and the M-0245 High Speed Sync Check Relay - which will assure the proper phase relationship between the new power source and the residual voltage of the still spinning motor bus in order to minimize potentially damaging system transients normally associated with power transfer schemes. The application and performance of these devices for high speed synchronous power transfer is also discussed INTRODUCTION Typically, generating plants have at least two available powel sources for the auxiliary systems associated with each generating unit.

A typical unit is illustrated in the simplified one-line diagram of Figure 1.

Transmission System m Generator m Station Step-up Service INTransformer N Transformer i

dy Unit Auxiliary N Transformer l

Auxiliary Se rvice s Bus 28 119 M

M sre.tro e i

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While the generating plant is operating normally, the power required by the auxiliary systems supporting the generator would be supplied by the unit auxiliary transformer connected to the bus structure between the generator terminals and generator step-up transformer. However, with this unit configuration, the auxiliary systems must be supplied from a separate power source during the normal unit start-up and shut-down sequences when the generator is unable to L

support a load, as well as those instances when the unit auxiliary transformer is taken out of service for maintenance or must be disconnected to clear a trans-mission system or generator fault; During these periods the station auxiliary service transformer must be connected to supply the power requirements of the auxiliary services. This process of exchanging power sources is commonly referred to as a bus transfer.

Another common configuration of generating plant equipment is illustrated in Figure 2.

In this configuration the power required for the auxiliary systems during the normal start-up and shut-down sequences may be supplied through the unit step-up transformer. With this configuration, bus transfers are required for those situations when the power circuit breaker connecting the generator step-transformer to the power system must be opened to clear a fault and the generato:

must be taken out of service, i. e. a transformer fault.

In nuclear generating plants at least two off-site sources of power, in addition to an on-site auxiliary ac generator, are required for the supply of the engineerec safeguard auxiliary systems (Class IE). If the unit is connected in a manner similiar to the configuration of Figure 2, the second off-site power source is required, as a minimum, to have the capability of starting and operating the Pi E systems and related loads. In plants having more than one generating j

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Auxiliary Station Service Generator FIGURE 2 i

t installed units. In nuclear installations, all of the unit auxiliary systems must

• The be capable of transfer between either of the off-site power sources.

Class 1E equipment must be capable of transferring between either of the off-J sources as well as the on-site auxiliary generator supply.

BUS T IETHOLS na-Aon m

f.,.i nr U Tae n'.sthods pre sent'.v employed to transfer bus power sources vary from

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closing of the circuit breaker between the auxiliary motor bus and the new source.

These schemes involve a risk as many or all of the motors, when re-energized, will draw currents which are significantly greater than their normal operating Unless the new source has sufficient capacity to restart all of these current.

i motors, nonessential. equipment must be tripped from the auxiliary service bus prior to closing the circuit breaker or the total re-starting current may prevent some or all of the load from re-accelerating. These schemes require voltage measuring devices that are a'ccurate over a significant frequency range.

If the delayed scheme waits until the residual voltage of the auxiliary motor bus is below a predetermined level, care must be taken to prevent the total applied voltage from being excessive. If the breaker is closed when the internal motor voltage is out of phase with the new source, the applied voltage as seen by the machine will be the vector difference of internal machine and source voltages.

As the magnitude of this applied voltage may 'be significantly greater than the original source voltage, this may result in current levels above those normally experienced in starting.

NEED FOR HIGH SPEED SYNCHRONISM VERIFICATION In each of the above schemes, some form of synchronism verification device should be ineluded to prevent the new source from being connected out of phase.

As plants increase in size and complexity, the need for high speed bus transfer schemes becomes increasingly more desirable in order to enhance the security and reliability of the critical plant auxiliary systems.

Since design economics will not permit the increased cost associated with the ed switchgear ratings required for reliable parallel transgoggical plant

, s, it is necessary to examire the dynandes of the auxiliary motor

When disconnected from a source of energy, rotating equipment will decelerate at a rate which is a function of the initial rotational inertia and the retarding torque. In a large nuclear generating plant, the boiler draft fans, reactor coola pumps and other large motors with heavy flywheel loads would be expected to decelerate slower than the lower inertia loads associated with circulatir g water or bearing lube pumps. Considering that a typical auxiliary services bus would have a combination of these loads connected, the deceleration of the total system becomes a complex function of the total system inertia, the time constants 4f the individual motor loads, the trapped flux in each machine, as well as the individ-ual characteristics of each machine. In such a system, the larger machines with high inertia loads and longer time constants tend to act as generators and supply energy to the smaller machines with lower inertia and shorter time constants. As a result, the total auxiliary bus may be viewed as an equivalent machine decelerating at a composite rate.

The frequency of the residual voltage present on the auxiliary induction motor bus during the de-energized transfer period will decay at a rate dete rmined by the complex " average" of the spectrum of parameters associated with the

" free-wheeling" motor bus. During this transfer period, each of the motors will draw upon the total stored rotational energy of the system. Those machines with higher inertia will act as generators, converting the stored rotational energ into the electrical energy required to maintain the machines with heavier loading The system frequency will decay as the stored energy is dissipated by the load.

If a synchronous machine is connected to the above bus, the bus frequency is now determined by this machine as the rotational frequency of the synchronous machine is proportional to the residual bus voltage.

Since the field of this macht F9 122

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will remain connected during the transfer period, this additional source of energy will help to maintain the residual bus voltage for a somewhat longer period of time.

The rate of change of the residual bus voltage and frequency is now dependant upon the deceleration of this machine.

Upon re -energization, a still spinning motor may be damaged by the synchronizing torque associated with the phase angle between the residual and supply voltages.

Synchronous machines are more susceptible to this type of damage than induction machines as the rotor of the synchronous machine must actually move thru this phase difference,while in the induction machine, this phase difference is partially accounted for by a shift in the air gap flux.

The use of large synchronous motors in power plant applications has been some-what limited by this phenomenon together with the performance of previously available synchronizing equipments.

The voltage magnitude of the equivalent auxiliary bus is a function of the trapped flux remaining in the machines at the time the bus is disconnected from the original source and the rate at which the trapped flux is removed from the system.

In addition to the considerations associated with machine dynamics in selecting the scheme to be used for the bus transfer, is the phase relationship between the power sources. If the off-site source is from a different voltage transmission network than the high voltage side of the generator step-up transformer, the assumption that the phase difference between sources is small enough to be negligible is no longer valid and this relationship must be considered to be a function of the network load flows. In those situations where the phase relation between sources is a variable, a means of blocking the transfer must be provided where a large phase difference will result in an excessive voltaoe being applied 3o9 c

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to the auxiliary services bus during the transfer.

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i SYNCHRONOUS TRAhSFER I

[

In reviewing the basic transfer schemes, it is apparent the security of each metho f

i is inhanced by the presence of a synchronism verification device. The parallel scheme requires this device to insure the phase relation between the two sources, especially when the second source is from a voltage level or network section g

different than the primary source. In this case, the device must be continuou' sly i

i t er.2rgized and capable of blocking the closing of the paralleling circuit breaker if the sources are out of phase. With delayed transfer schemes using voltage reduction techniques, the voltage measurement device must be accurate over a wide frequency range. In fixed time delay transfer schemes, the analysis of the auxiliary motor bus dynamics must determine the coast down time for the worst case combination of machines and loads to insure the residual voltage has decayed to a safe level prior to re-energizing the bus.

Since the economics of design will probably not permit the additional cost associated with the increased switchgear capacity required to separate the auxiliary motor bus from an external system fault occurring during a parallel transfer, not to mention the expense associated with the catastrophic failure of the unit auxiliary or station service transformers which would probably occur before the breakers could clear the fault; it is desirable to consider other high

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speed means of reliable' bus transfer.

The solution to these problems is apparent from a review of the equations.

describing the dynamics of the systems during a non-parallel transfer. If one assumes the electrical frequency of the motor bus, after being disconnected from power source by tripping the circuit breaker, will decay as a linear function of time, then the following equations express the frequen u.

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. phase ( 0 ) relations between the still-spinning motor bus (W Bus ), immediately after the breaker is opened, and the new source of power to be connected ( "Linel-If i

u

=

A Line (A+ + 2Ct) m

=

Bus then the difference in frequency is 23(B+2Ct C'(t)

=

W Line Au

=

=

Bus 23 Bt+Ct2+D (1) jaw

$(t)

=

=

C" =

4nC A w'

=

s where the constants A, B, C and D are functions of the rotating system.

If t is defined as the time at which (t) = 0 then from (1) o

-Bi./B -4CD 2

t

=

o 2C By defining TB as the time required for the circuit breaker to close its contacts after being initiated, it is apparent the advance time t f 11 ws the relation a

ta+TB=to (Figure 3) and t is found to be a root of the homogeneous (3) a differential equation:

(4)

C (t) + TB c' (t) + KT 0"(t) = 0 B

by substituting (1) into the above equation

-(B+2CTB) 1 (B+2CT3)2 - 4 C(D+ BTB+2KT I

B (5) a 2C and from the relationships (2) and (3) above the constant K is determined T B (6) to be:

K

=

2 Substituting this value into (4) simplifies the solution for ta

-(B+2CTB) i B -4CD QJ 125 2

.)

which checks with the relation t, + TB=t o and the solution for t in (2) above, o

Graphically this solution and the system dynamics can be illustrated as follows:

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FIGURE 3 It is now evident there are two solutions to our. problem of synchronous transfer:

(1) if the phase difference between th"e motor bus and auxiliary power source changes slowly after separation from the original source, there is a phase window in which the circuit breaker can be closed and (2) this window will reappear after the time t -

a These solutions to the problem imply two separate synchronous transfer schemes which will provide safe high speed means of keeping critical plant equipment operating.

TR ANSIENT INRUSH Considerable misunderstanding exists regarding the magnitude of the inrush curret at the time the circuit breaker is closed to re-energize the motor bus. It would appear that if the bus voltage had decayed to a level E, the inrug urgg would

-~ > wh e.*re E is the magnitude of the new source voltage. This is not true, however, a

as the machine is still rotating.

The basic problem in the transfer of a running motor between sources of power is the replacement of the energy lost by the motor during the transfer time.

Assuming an induction machine, the transient associated with the re-energization can be separated into two components; one which re-establishes the field and the second which re-accelerates the load. The transient due to re-establishment of the field will last.for a short period as the field is increased in magnitude to th level corresponding to E, volts. Since the energy stored in the field is on the order of one percent of the total stored energy,this transient will have little or no relation to the transient associated with the re-acceleration of the machine which will last much longer.

t One way of estimating the re-acceleration transient is to consider that the stored rotational energy of the system varies as the square of the rotational frequency.

For a small decrease in speed, the percentage change of stored rotational energy will be approximately twice the percentage change in speed. For example, if during the transfer period. the frequency of the machine bus decreases.5 percent, this corresponds to a loss of 10 percent of the stored energy.

Starting e.rrent can be divided into two components'; one being the load componen which is a function of the motor speed as it accelerates, the second being the component required to overcome the internal losses of the machine and establish the stored energy.

In re-acceleration, the load component is nearly constant and approximately.

equal to the full load current for a small reduction in speed during the transfer The second component is proportional to twice the percentage change sequence.

in speed. As can be seen, the composite re-acceleration inrush current transie 29~127 is quite different from the starting current inrush.

4 Note that if even one synchronous machine is present and a 25 percent residual voltage relay is used to initiate a delayed transfer, then the restart conditions will be based on this voltage as well as 25 percent speed, an obviously unaccept-able situation in most applications as the synchronous machine will attempt to maintain a voltage proportional to speed.

OPERATION OF SYNCHRONOUS TRANSFER DEVICES

. The devices employed in either of the above synchronous trans-fer methods must be capable of accurate phase angle measurement over a frequency range and independant of the source voltages; exhibit fast reset time; be capable of energizing breaker close circuit directly, and be capable of being continuously energized by the potential sources. Both the Beckwith Electric M-0245 High Speed Sync-Check Relay and M-0236 Power Transfer Relay were designed to meet these requirements. In addition the solid state circuitry in both devices was designed to withstand the transients and surges normally encountered in a station environment.

The M-0245 High-speed Sync-Check Relay measures the phase angle between the rotating motor bus and auxiliary (new) source by comparing the coincidence of the voltage waveforms. In addition, the relay verifies the magnitude of the new voltage is between the upper and lower limit values set on the front panel controls.

The overvoltage limit comparison provides protection against excessive voltage being applied to the motor bus while the undervoltage limit comparison insures the source voltage is aufficient to pick up the additional load imposed by the motor bus after its connection.

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Isolation Phase Motor Transient Circuit Bus Protection Upper Isoir. tion Limit Auxiliary V ltage Source Transient Comparison Protection 22 2 Lower h

Limit Voltage Comparison Transfe r Initiate Time Delay FIGURE 4 Assuming the applied potentials are within the preset control limits for voltage and phase angle, the unit will respond to the closing of the initiate contact by closing the output circuit after a brief time delay, included to ensure that the arc of the interrupting breaker has been extinguished.

The unit will reset within one cycle if the phase angle measurement exceeds the phase angle setting. If the new source voltage varies outside either of the voltage control settings the unit will reset and inhibit closing of the circuit breaker.

The output of the M-0245 consists of a group of extremely fast VMOS power field effect devices in parallel capable of switching an inductive 15 ampere, 300 volt de load on and off. This output is transient protected as well as electrically isolated f-om the remainder of the relay.

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The M-0236 Power Transfer Relay monitors the motor bus voltage and auxiliary source voltage, precisely measures the phase relationship of these voltages 0(t) and computes in real time the rate of change of phase angle (slip frequency) c'(t) and rate of change of the slip frequency 4"(t). Upon initiation the M-0236 solves the differential equation 0

(8)

C(t)

+

T O'It)

+

0"(t)

=

B 2

i I

for ta (advance time) required to close the circuit breaker at zero phase difference given the breaker closing time., TB*

Within the M-0236 the phase coincidence of the' positive and negative zero crossings of the input voltages are monitored and converted into a voltage pro-portional to the phase difference. These two signals are summed to produce a stairstep approximation of a triangular wave. This waveform ( 4(t)) will increase from zero volts at zero phase difference to 10 volts representing a 180 degree phase difference, then reduce in level back to zero volts over the period of one slip cycle.

The rate of change of phase angle ( o'(t)) or frequency difference and rate of change of frequency difference ( 0"(t)) signals are obtained by passing the phase angle signal through successive derivative amplifiers. These signals are appropriately combined with a voltage proportional to the programmed breaker closing time.

The real time phase information o(t) is then compared with the combined signal accounting for the terms in the following equation T

T C

(t) +

4 (t) = - 0 (t)

(9)

B B

At the point in time when these voltages are equal, a pulse is provided to the out-put logic circuit which issues the close command to the circuit breaker.

This logic network may inhibit the closing pulse from activating the breaker close circuit if any of the following conditions are outside the preset cgyol gts:

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4 Iower limits as determined by the netting ci calibrated front panel controls.

These settings provide security against closing the motor bus into a faulted supply line as well as limiting the stress on the rotating equipment due to excessive voltage.

2)

The frequency difference between the auxiliary source and the residual machine voltage must be less than the setting of the calibrated fr3quency difference control. The setting of this control may be determined from the swing equations for the motor bus and its associated machines as well as the transient stability limit of the auxiliary motor bus system.

3)

The frequency of the auxiliary source must be within il hertz of 60 hertz.

The value of this limit was arbitrarily selected during the initial design and may, if necessary, be changed in the factory to correspond to the under-frequency limit for load shedding for any given system.

These conditions must also be satisfied before the unit will permit closing of the controlled circuit breaker:

1)

The M-0236 must have been initiated by the closure of an isolated external contact signifying a bus transfer is required.

2)

The external power source must have been previously connected for at least 2 seconds prior to initiation by the above external initiate contact.

If, for some reason, the internal reference and power supply voltages are out of tolerence, the unit will inhibit the output; thereby preventing misoperati neous computations or comparison due to power supply failure.

The unit will provide an output enabling the circuit breaker to close for a period of 0. 3 seconds when all of the above conditions are met a th per phase relationshin exis :s between the inout voltaees. The unit will attempt to close the

.. ' i

- id -

.4 breaker once at the first opportunity and then will be inhibited from further operation for a period of 10 seconds to allow any back-up devices external to the i

l unit to operate.

The output circuit of the M-0236 is the same as described above for the M-0245.

This circuit provides a direct _means of actuating the close circuit of the controlled circuit breaker without the additional delay associated with interpos-ing auxiliary $ elays.

HARDWARE PERFORMANCE The upper and lower voltage limit measurement circuits of the M-0236 Power Transfer Relay and the M-0245 High Speed Sync-Check Relay exhibit rapid response to a change in voltage which results in either the blocking or enabling of the output device.

For an instantaneous voltage change, this response time is dependent upon the initial value of the measured voltage; prior to the change, the limit control setting relative to the initial value and the total change in voltage.

Figure 6A illustrates these relationships. The family of response characteristics in Figure 6 illustrates the time response to a step change in voltage as a function of the magnitude of'the change and the limit setting relative to the voltage. prior to the change. To interpret these character-istics, assume the upper limit control was set at 130 V a', was 120 V ac and this

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c voltage rapidly increased'(instantaneously) to 150 V ac.

V

= 155 - 120 = 35 Volts V step Final -

Initial

=

0 - 120 = 10 Volts

• V

=

VSet Setting -- Y Initial From the curve, the voltage limit circuit would block closi in seconds.

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The response of these voltage limit circuits to a continuously varying voltage is presented in Figure 7. The response time.s again dependant upon the initial measurement value relative to the limit setting but is primarily dependent upon the rate of change in voltage magnitude. This response time is defined as the t

time required for the circuitry to respond to a voltage excursion across the limit band setting. This relation is graphically illustrated in Fig ure 7A.

In Figure 7, with the lower voltage limit control set at 105 volts, if the measured voltage were initially 100 volts and increased at a rate of 10 volts per second, 5 volts), the unit would enaMe

= V 105 - 100 (VChange Setting - V

=

=

Initial the output within 0.435 seconds.

The phase angle comparison circuitry of the M-0245 High Speed Sync-Check Relay requires one half cycle to measure the instantaneous phase angle between the input voltages. If during one half cycle the phase angle were within the

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preset limit and the following half cycle measurement were outside the limit setting, the logic circuitry would immediately block the relay output. As there is a half cycle uncertainty as to the actual location of this phase change, the time response to a phase change must be defined as one cycle.

In the M-0236, Power Transfer Relay, the instantaneous' phase angle between the measured' voltages is compared to the programmed' advance angle required to close the circuit breaker with zero phase difference. The predicted phase error due to a step change in frequency is plotted in Figu're 8.

Figure 9 illustrates the predicted phase error resulting from a decay in frequency of the motor bus.

These phase error predictions are based on the tihase difference across the open circuit breaker just prior to the closing of the breaker contacts and assutning tne remaining time before actual closing is zeg-gmputerized

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this simulation,. the M-0236 Power Transfer Relay consistantly demonstrated a total measured phase errar of less than 8 degrees.

CONCLUSION As shown in Figure 3, during a bus transfer there are two phase windows during which a synchronous high speed transfer between power sources may be accomplished. The first window occurs immediately following separation of the motor bus from the original power source. The duration of this window is a function of the deceleration of the motor bus as well as the amount and direction of the initial phase change at separation. This requires the

,,, synchronizing devices to be capable of disabling the breaker close circuit quickly in order to limit damage to the machines if the phase relation between the motor bus residual voltage and new source becomes excessive.

The Beckwith Electric M-0245 High Speed Sync-Check Relay has sufficient speed

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to satisfy this requirement.

A second phase window will exist at the end of one' slip cycle or a'360 phase angle rotation. The Beckwith Electric M-0245 Power Transfer Relay and M-0245 High Speed Sync-Check Rel'ay operate during this window. The M-0236 Power Transfer Relay will initiate closing of the circuit breaker based on the dynamics of the motor bus and the programmed breaker closing time.

Thus, re-energizatiori of the motor bus will occur with minimal phase error. The M-0245 High Speed Sync-Check Relay will enable breaker closing for a phase difference window on either side of this zero phase point and should be set based on the breaker closing time to limit the phase difference at the time of actual breaker closing.

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in keeping with good design philosophy, the synchronous transfer scheme employing either or both of these devices should be supplemented by a backup scheme utilizing a different method of transfer.

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o CLOSES ONLY IF ALTERNATE SOURCE VOLTAGE AND FREQUENCY ARE OK 23 ' b12

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4 POUER TRANSFER RELAY M-0236 SPECI FI CATIONS INPUTS:

(

o Ho to r Load Bus, 120 V ac nominal 0.15 VA burden.

• Auxiliary Source, 120 V ac nominal 0.15 VA burden.

e H-0236 Supply, 120 V ac 10%, 2 VA burden, 60 to 400 Hz.

o External d ry con tac t closure to initiate the transfer sequence o

(Transfer initiate Contact).

This may be an a uxiliary "b"

con tac of the main bus breaker.

o Breaker Closing Time ( p ro g ra mma b l e ).

Note:

All potential inputs are isolated.

The supply input and auxiliary source may be connected toge the r externally provided the po ten t i al transformer f rom this auxiliary supply has sufficient ca paci ty.

BREAKER CLOS ING TIME:

o Hay be prog ra mmed by two jumpers over a range of from 2 to 12 cycles.

oThe minimum time between opening the main breaker and cl os i ng the transfer breaker is 0.25 seconds, assuming a 5 cycle breaker closing time and proper phase coincidence at the end of this period.

o With a typical phase rotation time of one second (slip ratc of I Hz), the closing error will be within i10 OUTPUTS:

Solid state B r ea ke r Close Circuit is capable of controlling an o

inductive current of 15 amps at 300 V dc.

Closing signal will remain for 0.3 seconds.

Reset time is 10 seconds.

Operation of Breaker Close circuit is inhibited if the frequency o

of the auxiliary source is unstable, Ea ch a na log output has an output impedance of 10 KG referenced o

to terminal 7.

oThe following ana log outpu ts a re provided:

(1)

A Frequency, range:

'O to +10 V dc corresponding to O to 5i (2)

Phase Difference, range: 0 to 180 d eg rees corresponding to gg~ M'd 0 to 10 V dc (55.6 mV per degree).

n t

A (3)

Auxiliary Source Voltage, range:

0,t o 200 V ac Input corresponding to'O to 10 output.

STA TUS CONTACTS:

(1)

Auxiliary Source Vo l ta g e:

contact is closed when vol tage is within upper and lower limits set on controls.

(2)

Frequency:

contact is closed when the frequency difference between auxiliary source and motor bus is withir the set limit and the frdquency of the auxiliar source is between 59 and 61 Hz.

These contacts are 20 VA dry reed type capable of carrying 1 Amp max., switching a 100 V dc resistive load and withstanding,25,0 V,,d c open circuit.

CONTROLS:

140 Va UPPER VOLTAGE LIMIT fo r Auxil i ary.Vol tage, range:

110 o

LOWER VOLTAGE LIMIT-fo r. Aux i l i a ry Vol tage, range:

90 120 V ac a

A FREQUENCY LIMIT, ra n ge :

0. 5 to 5 Hz.

o Calibrated dials f acil i ta te stable field adjustment wi thout additional test equipment.,

LED INDICATORS:

UPPER VOLTAGE LIMIT OK:

Auxil i ary Vol tage less than se tting o f o

Upper Limit.

LOWER VOLTAGE LIMIT OK:

Auxiliary Voltage greater than setting

~

o of Lower Limi t.

• A FREQUENCY LIMIT OK:

Frequency Difference is within limits' set by con t.ro l.

• READY:, Unit reset and ready.

Breaker will close if vol tages anc f requencies OK and if Transfer initiate Con tac t is closed.,

e AUXILIARY FREQUENCY OK:

External Tra ns f e r initiate Contact is closed.

TRANSIENT PROTECTION:

o All voltage input connections and so l i d sta te Breaker Close Circi connections will withstand 2,500 V ac, 60 Hz to chassis or instrument ground for 1 minute.

I 'I.Q

L a These inputs will also withstand the ANSI SWC Test (C37.90a-1974).

and are d es igned to withstand the Fast Transien t Tes t.

g All inputs and outputs are electrically isolated f rom each o ther.

a i

• Use o f va ri s tor suppressors across contacts and from contacts to chassis ground is' suggested if these con tac ts a re to be tied to long wire runs.

RELIABILITY:

The H-0236 Power Transfer Relay is assembled on a single glass-epoxy printed circuit board thereby eliminating the need for plug-in con ne c tor s.

All semiconductor components are hermetically sealed a nd of the highest and most reliable quality available.

Highly stable instrument grade capacitors and resistors are utilized in critical measurement circuits to minimize the possibi.lity of error.

ENV IRONMEN TAL:

Temperature Range:

Unit is designed for proper operation o

over amb ien t range of -40 to +80*C.

Slesmic:

Unit is designed to meet the requirements of nuclear o

ins talla tion.

Humidity:

85% relative humidly, o

Fungus Res is tance:

Circuits are coa ted with f ungus retardan t o

to inhibit f ungus g row th.

PHYSICAL:

Size:

19" wide by 31" high by 13" deep (48.26 cm X 8.89 cm a

X 33.02 cm).

Requires two rack units space in a standard 19" ra ck.

Hay also be panel mounted hor izon ta ll y o r ver ti ca l ly, Weight:

15 lbs.

(6.75 kg).

o

• Shipping Weight:

20 lbs. (9 kg).

6 SYNCROCLOSER ) COVER KIT:

A H-0217 tran s pa ren t plastic cover may be ordered with the H-0236 easily adde,d at any time.

or 28 ~L15

TABLE OF C0i1 TENTS POUER TRANSFER RELAY APPLICATION GUIDE M-0236 I

I n t'ro d u c t i o n 2

i Application l

Typical Transfer Scheme Figure 1 3

Industrial Load Res tora t ion Figure 2 4

6 O pera ting Principles Front Pa nel Controls Figure 3 8

Adjustment 9

Recommended Connections for inductive Loads Figure 4 10 External Connections Figure 5 11 Hounting and Outilne Dimensions Figure 6 12 Pa n el floun t i ng Dimensions Figure 7 13 Block Diagram Figure 8 14 Design Changes 15 Warranty and I ndemni fi ca tion 16 9

G E9 146

a s-BECKWITH ELECTRIC INSTRUCTION BOOK UPDATING SERVICE 1

Your instruction. book may have been reproduced in p~ art on a page copier.

This enables us to certify that your book is updated and correct in every detail.

The following is a record of the control for which this book is certified.

CUSTOMER CUSTOMER ORDER NUMBER BECKWITH ELECTRIC SHOP ORDER NUMBER SERI AL NUMBER (Stamped on Printed Circuit Board).

CERTIFIED CORRECT If unsigned, this book is for general informa tion purgosos,

accura t as of the da te printed on th e back cover.

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INTRODUCTION The M-0236 is a relay specifically developed for power transfer of large motors and motor buses.

This type of transfer is classifle as synchronous transfer, ie.,

allowing transfer of power when the phase difference referred to the new (auxiliary) source is very near zero degrees.

. Consider the typical power plant system of Figure 1.

Under normal conditions Breaker A is closed, Breaker B is open.

Under abnormal conditions, such as with a fault to the right of the generator transformer, it is desired to transfer the motor bus.t o the aux!Ila transformer by closing Breaker B.

Many schemes may be ut!!! zed to perform this transfer, however limitations and potential dangers should be' considered for each scheme.

With synchronous transfer, Dreaker B is initiated prior to the phase difference between the auxiliary'and motor bus reaching zero de'grees.' The time required for the phase difference to reach zero degrees is the time Breaker takes to close, ie.,

the time required by the contacts of Breaker B to "make" after being Initiated.

Thus when the contacts of Breaker "make",

the phase difference is very near zero degrees and transient power flow.is minimized.

The theory and internal. operations of the H-0236 are beyond the scope of this guide.

The interested reader is referred to Beckwith Electric publications " Synchronous Power Transfer, the Analysis Leading to the Development of the~Beckwith Electric H-0236 Power.

Transfer Relay" and " Synchronous Power Transfer, the Development..

and Performance of the peckwith Electric H-0236 Power Transfer Rela The H-0236 Power Tra'nsfer Relay looks at potential tra,nsformer outpu fro.m the motor bus and' auxillary source.

The ci'rcuitry within the H-0236 will initiate c' losing at a'given time before zero phase di_fference with this time set to the breaker closing time.

Proper aux.111a,ry voltage' limits, auxiliary frequency 1imits and frequency difference limits must be met before closing I s. permi t ted. -

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APPLICATION The Beckwith El ect ric H-0236 Power Transfer Relay is a solid state device specifically developed for the safe, high-speed, synchronous transfer of large rotating electrical machines from one source of power to ano ther.

Consider t'he s-implified typical generating plant system as shown in figure 1.

Und er norma l op.e ra t ing conditions, the generator would be used to supply the plant auxiliary service power requirements (Breaker A closed).

A transformer fault

, result.ing in the emergency shutdown of the generator would also i n t e r r-u p t power to the motor bus.

It is desi rable to restore power to this bus as quickly as poss'31e without damaging the ro ta ti ng equipment.

Closure of Breaker B would accomplish this objective, providing a means is available to q'u l c k l y check synch roni sm be twe'e n the a uxiliary power source 8

and the varying frequency of induced voltage of the rotating equipment.

The M-0236 provides the means of verifying synchronism together with the additional consideration of the closing time of Breaker B.

This results in the abili ty to be able to predict the point in time when the proper phase. rela tion between the vol tages will exist and to initiate breaker closing so tha t safe and hynchronous res tora tion o f service results.

That is are closed when the phase to say,. the contacts of Breaker B difference between the motor bus and auxiliary source is very nearly zero degrees thereby mini'mizing transient power flow.

The theory and internal operations of the M 0236 are beyond the scope of this guide.

The interested reader is referred to B eckwi th Electri c publica tions " Synchronous Power Transfer, the Analysis Leading to the Development of the Beckwith Electric H-0236 Power Transfer Relay" and " Synchronous Power Transfer,.

the Developmen t and Performance of the B eckwi th El ectric H-0236 Power Transfer Relay".

The M-0236 Power Transf er Relay senses the outputs of the po ten ti t transformers connected to the motor bus and the auxili ary source.

The circuitry of the M-0236 initiates breaker closir, at a programmed time (breaker closing time) prior to zero phase difference.

Opera tion of the M-0236 is i nhi bi ted if preset voltage, frequency and frequency difference l imi ts are exceeded prior to ini tia tion of breaker closing.

To understand the value of the M-0236, fi rs t consider some of the other methods currently in use and th e p robl ems that have been experienced with each.

t One method, widely used, is to ini tia te closing the second j

breaker and tripping of the fi rs t breaker by the same e l e c t r i ca l contact.

This requires the closing time of the second breaker i

to always bo slower than the tripping time of the f i rs t.

P00R ORGINAL

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GENERATOR GENERATOR

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TO SYSTEM r,

TRANSFORMER J

owW MAIN TRANSFORMER WM N.C.

BREAKER A

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C MOTOR BUS N.O.

BREAKER B

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' AUXILIARY 3b TO SYSTEM Or OTHER SOURCE TRANSFORMER OF POWER.

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If this race is not won at the time of a genera tor faul t, fault current can flow momentarily through the station service transfor resulting in the dramatic f ailure of the transformers.

A second method is to initiate closing of th e second breaker with a contact on the first.

This guarantees opening of the first breakers; however, the transfer time now can often be sufficient to produce a worst case phase angle between the induced mo tor vol tage and the new source.

This has been known to snap motor shafts.

A th i rd me thod is to let the mo to r voltage decay,to 0.25 PU magnitude.

At this value the wors t case current inrush is within motor design limits.

The time may be so long, however, that an undesired or damaging plant sh utdown.may occur.

The H-0236 permits transfer a t th e first ava i l a b l e s y.nc,h rono u s condition.

The phase error in closing will be the sum of the internal H-0236 error and tha t caused by to l e r ance in breaker closing time.

The H-0236 has been thoroughly tes ted with a comp u te r-con tro l l ed signal synthesizer and digitizing voltmeter with a wide range of possible motor voltage conditions.

At all times the total error was found to Ene wel l wi th i n the l imi ts of 10*,

which ana lys is shows is safe for motors designed to withstand 1.3 times the "a c ros s-th e-l i n e" s ta r t i ng current.

The H-0236 is also capable of a wide spectrum of other uses.

The H-0236 will perform the breaker closing f unction o f the Beckwith El ec tr ic H-0193 automa ti c synchronizer, wi th nearly the same precision, down to extremely low slip ra tes.

The advantage of the H-0236 is i ts capability to follow rapidly changing speed characteristics.

This makes it a very precise means of synchronizing a wind turbine or small hydro genera tor whose speed is likely to fluctuata rapidly.

At the same t i m e,"

the relatively rugged ' cons truction o f these small machines will permit synchronizing wi th a g rea ter AF than allowable for la rger conven tiona l ge ne ra to rs.

The H-0236. Power Transfer Relay can also be applied in the case of a large industrial load fed by a tapped tra ns mi s s i on line as illustrated below.

Wm I

INDUSTRIAL LOAD D IbI.

FIGURE 2.

lHDUSTRIAL LOAD RESTORATION SCHEME

L A line fault would result in ci ca ring of the faulted line and a high speed reverse power relay could be used to trip the industr Breaker I and ini tia te the'H-0236.

The H-0236 would then synchronously restore power to the industrial load following a high speed reclosing of the line b're a k e r s.

Similarly, many industries have found tha t thei r cr i tica l processe necess i ta ted ins talla tion of an emergency source o f powe r whi ch could be used if an interruption of service by the powe r comp any

occured, in many o f th es e ca s es whe r e co generation does not exist, the utility has i nstalled a second feeder from a sepa ra te subs ta tion.,

in this situation let us assume tha t the firs t feeder is capable of s upplying the normal full plant load and the s econd feeder has the capacity to handle only the critical load and the agreemen b e tw e en the industry and the utility is tha t the second feeder i

is for emergency use only.

in this ca se a fast synchronous e

trans fer is required for process continuity.

If the two feeders

• differ by a phase angle due to routing, the H-0236 can quickly provide the requi red power transfer.

Once the main feeder is restored, the H-0236 will provi de the means necessary to restore the mo tor load to the primary source.

The engineering staff of Beckwi th El ectri c will be glad to assist in the de tailed appl i ca tion of this valuable new relay.

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5 OPERATING PRINCIPLES Refer again to Figure 1.

The motor load bus inputs of the potential H-0236 would be a t tached to the mo tor bus via a inputs of the H-0236 would transformer and the auxiliary source be attached to the auxiliary t ra ns f o rme r via ano ther poten tial transformer.

Power could be derived from the auxiliary trans fo rme r by. paralleling the auxiliary source ' inputs 'and the power inputs of the H-0236.

Power could also be derived elsewhere by wiring the power inpu ts of the H-0236 to the app rop ri a te source.

~~

Breaker closing time and front panel controls should be' adjusted according to the breaker to be closed and the system involved.

The close circuit of Breaker B should be wired to rear terminals A and B, with terminal A the mos t positive and terminal B the.

most negative.

The B contart o'f Breaker A should be used.co initia tra sfer by wiring this contact to the H-0236 initiate' Transfer term!nals.

Should protective relaying or manual means. trip Breaker A, then the contact of Breaker A will Initiate ansfer within the H-0236.

The H-0236 will begin operation and, should conditions be OK for transfer to the auxiliary transformer, the H-0236 will Initiate closing of Breaker B.

When these contacts "make",

the phase difference between the motor bus and auxillary will be very near zero degrees.

The reset time should be mentioned briefly.

The breaker close circuit remains closed for 0.3 seconds at which time the H-0236 goes into a lock-out mode for 10 seconds.

Lock-out simply means that the unit disregards any inputs or commands.

Af ter the 10 seconds, the H-0236 automatically resets and awaits another transfer operation. However, the " Initiate Transfer" input does not have to be reset to initiate a second closing output.

If the

" Initiate Transfer" input is kept closed, a second close output will occur after the 10 second reset time.

Should conditions warrant transferring the motor bus back to the main transformer, the H-0236 may be called upon for this operation First, the close circuit of Breaker A must be wired to the H-0236 terminals A and B.

Il0T E :

The term " wired" could refer to using relays or auxil.lary r.ontacts on breaker release switches to complete o r "w i re" these circuits.

The breaker closing time should be changed if the closing times of Breakers A and B differ.

The main transformer should be wired to the auxiliary source input of the M-0236 via a potential transf Using the B contact of Breaker B to initiate transfer within the H-0236 will allow transferring the motor bus from the auxillary transformer to the main transformer when Breaker B is tripped.

It should be noted that transfer will occur only if conditions 29 153

1 at the main transformer are OK, ie.,

main source frequency OK, A Frequency OK and main source voltages OK.

After transfer to the main transformer i s completed, the circuits should be wired back for their original operation.

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O MO236 POWER TR ANSFER O

RELAY UPPER VOLTAGE -

LOWER VOLTAGE -

CFREQUENCY LIMIT LIMIT LIMIT O READY Q

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FRONT PANEL CONTROLS

s.,

t ADJUSTt1ENT Refer to Figure 3 which shows the f'ron t p.anel controls.

Adjust the UPPER VOLTAGE LlHIT control to the value which the auxiliary source voltage may not exceed if breaker closing is to be permitted.

Adjust the LOVER VOLTAGE.LlHIT control to the value which the auxiliary source voltage must exceed if breaker closing is to be permitted.

Adjust the A Frequency LiHIT control to the value which the frequency dif ference must not exceed if' breaker closing is to be permitted.

SETTING THE BREAKER CLOSING TIME Refer to Figure 5 which shows external connections.

I f the M-0236 is to be used with a single breaker, a Jumper may be added to set t he. co rrec t breaker closing time.

One Jumper from rear terminal 17 to terminals 8 thru 16 covers most breaker closing times.

However, i f slower breakers are employed, the x 2 multiplier can be used by adding a jumper from terminal 18 to 19 For'best operation, an additional one half cycle should be added to the breaker time, this compensates for the one half cycle delay within the H-0236.

As a rs example, a Five cycle breaker would be

" programmed" as a five and one half cycle b r e a ke r..

When.the H'0236 is used with several breakers of different closing times, these circuits can be closed at the time the breaker is selected.

This can be accomplished by relays located near t.h e H-0236 or by auxiliary contacts on b caker select switches.

OPERATING INDUCT'.

LOADS The Solid State Breaker Close Circuit is fully protected from transients and inductive spikes.

However, it is strongly recommendec when driving highly inductive loads to utilize the " transient suppres diode" within the H-0236 for added suppression.

This diode is available f. rom rear terminal C, (see Figure 4).

The ty p,i ca l' application will illustrate the most effective use of this diode.

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__3ATTERY POSITIVE Q

m J<z INDUCTIVE e2 LOAD

,O BATTERY 9-NEGATIVE 2 CC<

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WITH THIS C 0!!H E CT I 0 tl, T il l.' H-0236 0UTPUT IS CAPABLE Of SAFELY OPENING 15 AMPS OF CU R R E rlT t il A B R E A KE Ps CLOSE SOLEt10!D WITH A BATTERY VOLTAGE UP TO 300 V DC.

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--.......~.n e n.. u c. T i n u e eno i u nise r s u c- 's n a n c

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i FUNCTION 1

Hotor Load Bus Potential input Hot j

2 Motor Load Bus Potential input Heutral l

3 Auxiliary Source Potential input. Neutral 4

Auxiliary Source Potential Input Hot 5

Phase Diffbrence Analog O u-t p u t,.

6 A Frequency Analog Output 7

0 Volts, common for analog ou t p u t s: s hou l d be I

8 Breaker Closing Time:2 cycles' I

9 2.5 cycles 3

cycles Progr<

10 Break 11 3.5 cycles Time 4

cycles d!

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5 cycles g

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I 15 5.5 cycles 6

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16 s

17 Breaker Closing Time, Common j

18 Breaker Closing Time, Hultiply x 2 dl 2

19 0 Volts 20 Initiate Transfer input ll initia l

21 0 Volts T r a n s. f I

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22) Status Contacts, Closed When 23j Auxiliary Voltage OK 24'l Status Contacts, closed When

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& Auxiliary Frequency OK 25, A Frequency l

26 120 V ac Power Neutral i

27 120 V ac Power Hot 28 Auxiliary Source Voltage Analog Output h.

Solid State. Breaker Close Circuit Output D

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Transient S,u p p r e s s o r' Diode D

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FJG. 3. M-0236 EXTERNAL CONNECTIONS 29 ~1[ig

..,. 4 Q MOUNTIflG The following Fig. 6 shows outline dimensions for any of the units.

This fits a standard 19" rack mount and. requires two rack units of height.

Fig. 7 shows the cut out required for panel mounting.

The unit can be mounted horlaontally or vertically.

A transparent cover and mounting bracket set is available to cover the knobs.and prevent accidental resetting.

TERMINAL BLOCK A-Il 6-32 TERl!I!JALS l'.AX TER}!IllAL 1*IDTil.313" (8nn) 8-32 TERMINALS TERMINAL BLOC I*p_un_____=___1-ze___1--'p,,,,,,[r,

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OUTLINE DIMENSIONS FOR ALL SYNCROCLOSER*

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DESIGN CHANGES Some simple changes are recorded by serial number.

Examples are changes in the detailed rating or manufacturer of a component where either the new or old part will perform properly.

More complex changes are made by adding a suffix letter.

The rule is that it must be possible to use any later version as a replaceme for an earlier version.

The opposite may not be true because of features that were added.

If later units are not Interchangeable for oider units, a change in Model Number is made.

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NARRANTY The following Warranty and indemnification clauses f orm a part of any contract for sale by Beckwlth Electric Co.,

Inc. of the merchandise described in this publication.

Seller hereby warrants that the goods which are the subject matter of this contract will no manufactured in good workmanlike manner and all materials used therein will be new and reasonably suitable for equipment. Seller further warrants that the services to be performed shall be performed in accordance with Industry practices.

Seller warrants and guarantees that if, during a period of 2 years from date of shipment of the equip-ment or i year of successful operation, whichever period is shorter, sold equipment or the services rendered shall be found by the Purchaser to be faulty or shall fall to per-form in accordance with or specifications applicable thereto, Seller shall Immediately upon receipt of said equipment, shipped f reight prepaid to Seller's facility, at Seller's expense correct the same.

The Seller's responsibility hereunder shall be limited to the replacement value of the equipment furnished under this contract and the cost of the services furnished. The foregoing shall constitute the exclusive remedy of the Purchaser and the sole liability of the Seller and is in llou of all other warrantles wheth,pc written, oral, impiled or statutory, except as to the title of the Seller to the equlpoon furnished. No implied statutory warranty or merchantability or of fitness for a partic-ular purpose shall apply.

Seller does not warrant any product or services of others which Purchaser has designated.

Units will be repaired rapidly and returned at no cost and with return transportation paid if the fault is found to be due to workmanship or failure of material.

If the fault is due to abuse or misuse, a modest charge will be made.

Repair can normally be expected to take one week.

It faster service is required it should be requested at the time of return.

Any equipmeret returned for repair must be sent with transportation charges pald.

The equipment must remain the property of the user.

The warranty is vold if the value of the unit is invoiced to Beckwith Electric at the time of return.

SELLER MAKES NO WARRANTIES EXPRESSED OR IMPLIED OTHER THAN THOSE SET OUT AND Ill NO EVENT IS LIABLE FOR CONSEQUENTIAL DAMAGES OF WHATEVER HATURE.

INDEMNIPlCATION a4 The sellar shall not be liable for any property damages whatsosvar or cloins of'any kind whether based on contract, warranty, tort including nagilgence or otherwiss, or for any loss or damage erlsing out of,* connected with, or resulting from thls contract, or f rom the performance or breach thereof, or from all services covered by or furnishad' under thlt contract.

In no event, whet.her on contract, warranty, tort including negligence or otherwise, or under any facts or circumstances, shall the Seller be Itable for special, incidental, exemplary or consequential damages including, but not ilmited to, loss of profits or revenue, loss of use of the equipment or any associated equipment, cost of capital, cost of purchesed power, cost of substituto equipment, f acilitlos or services, downtime costs, or claims of customers of the Purchaser for such dazan-S.

Under no circumstances shall the Seller be liable for any personal Injury whatsoever.

When the equipment furnished hereunder or any services f urnished hereunder are to be por-formed on or lo connection with any nuclear Installation or activity, Soller shall hava no liability for any nuclear damage, injury er contamination to any property located at the site and Purchaser Indemni fies Seller against any such liability. Purchaser In-demniflos Seller against any such llability, whether as a result of brosch of contract, warranty, tort including negilgence or otherwise.

The Invalidity, in whole or part, of any of the foregoing paragraphs will not a f f oct the romalnder at such paragraph or any other paragraph of the contract.

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FOR ELECTRIC ~ GENERATING PLANTS FOR INDUSTRI AL PLANTS

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o FOR SYNCHRONOUS TRANSFyR.OF MOTOR BUS BETWEEN ALTERNATE SOURCES o ACCURATEL. CLOSES HIGH SPEED BREAKER AT FIRST AVAILABLE ZERO PHASE CONDITION r{

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POUER TRANSFER RELAY M-023b.

APPLICATION Synchronous tra'nsfer of auxiliary services a t a genera ting plant or the mo tor load in,an industrial plant is highly desirable to prevent either damage to cr it ica l. motors or an u nplanned sh u tdown.

A s ig ni f i ca n t induced vol tage will remain at the terminals of a ro ta ti ng machine for a period of time following removal of power.

If, during the power transfer sequence, the phase angl e of this vol tage relative to the auxiliary source is ignored, severe damage to-an expensive machine or process may result.

The M-0236 Power Transf er Relay provides a hi gh-speed mea ns-to synchronously close a transf er breaker onto the disconnec ted but still spinning mo tor load, thereby minimizing damage to th e machi nes..

This device also provides a means of synchronously connec ti ng small and medium size genera ting uni ts to a power system on the fly.

SPECIFICATIONS i

IN PU TS:

• Mo to r Load Bus, 120 V ac nominal 0.15 VA burden.

Auxiliary Source, 120 V ac nominal 0.15 VA burden.

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M-0 236 Su pply, 120 V ac t10%, 2 VA burden, 60 to 400 Hz.

a o External dry contact closure to initia te the transfer sequence (Transfer initiate Contact).

This may be an auxiliary "b" contact of the main bus breaker.

Breaker Closing Time (programmable).

o Note:

The supply input and auxiliary source may be connected to ge th er externally with certain limi ta tions as explained in the Applica tion Guide.

OUTPUTS:

Solid sta te Breaker Close Circuit is capable of controlling an o

inductive current of 15 amps a t 300 V dc.

Closing signal will remain f o,r 0.3 s econd s.

Reset time is 10 seconds.

Analog data outputs are p rov i d ed fo r. the following signals:

A Fr equ ency, Auxil i a ry Source Vol tage a nd Phase Difference.

Opera t iona l s ta tu s co n ta c ts for frequency and vol tage conditions are also provided.

These ou tpu ts are sui tabl e for us e wi th exi s ti ng or f u tu re supervisory control systems.

CO NTROLS :

UPPER VOLTAGE LIMIT for Auxiliary Vol tage, ra ng e :

110 - 140 V ac.

o LOWER NOLTAGE LIMIT f or Auxiliary Vol tage, ra n g e :

90 120 V ac.

o A FREQUENCY LIMIT, range:

0. 5 to 5 Hz.

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o UPPER VOLTAGE LIMIT OK:

Auxiliary Vol tage less than setting of

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Upper Limit.

LOWER VOLTAGE LIMIT OK:

Auxiliary Voltage greater than setting of o

Lower Limit.

o A FREQUENCY LIMIT OK:

Frequency Difference is within limits set by con trol.

• R EADY:

Unit reset and ready.

Breaker will close if voltages and frequencies OK and if Transfer initia te Contact is closed.

• AUXILI ARY FREQUENCY OK:

Frequency is within 59 to 61 Hz.

TRANSFER, INITIATED:

External Transfer ini tia te Contact is closed.

BREAKER CLOSING TIME:

May be programmed by two jumpers over a range of from 2 to 12 cycl es o

a The minimum time between. opening the main breaker and closing the transf er breaker is 0.25 seconds, assuming a 5 cycle breaker closing time and proper phase coincidence a t the end of this period.

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• With a typ i ca l phase rotation time of one se co nd (slip ra te of 1 Hz) the closing error will be,within 10*

TRANSIENT PROTECTION:

• All vo l ta g e input connections and solid state B r ea ker Close Circuit connections will withstand 2,500 V ac, 60 Hz to chassis or instrumen ground for 1 minute.

i oThese inputs will also withstand the A!!SI SWC Test (C37.90a-1974)

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and are designed to withstand the Fast Tra n s i en t Test.

oAll inputs and outputs are electrically i sola ted from each other, o Use of varistor suppres so rs across con tac ts and from co n tac t s to chassis ground is suggested if these contac ts are to be tied to long wira runs.

RELIABILITY:

The H-0236 Power Transfer Relay is assembled on a single glass-epoxy printed c ircuit board thereby elimina ting the need for plug-i n conn ec tor All semiconductor component s a re hermeti ca lly sealed and of the highest and most reliable quali ty available.

Highly stable instrument g ra d e capacitors and resistors are u tilized in cri tical measu rement ci rcui ts to minimize the possibility of error.

PHYSICAL:

• Size:

19'" wide by 3i" high by 13" deep (48.26 cm X 8.89 cm X 33.02 cm).

Requires two rack units space in a s ta nd a rd 19" rack, May also be panel mounted hor izontally or ver tically.

• Weigh t:

15 lbs. (6.75 kg).

• Shipping Weight:

20 lbs. (9 kg).

• Tempera ture Range:

Unit will operate properly over a temperature ra nge of -40 to +80* C.

These abbr evia ted s pecif ica tions should not be used for deta i l ed application.

Please contact Beckwith El ec tr ic for complete information and application assistance.

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BECX1/13TH ELECTmc CO., INC.

1181162ND STREET NORTH LARGO, FLORIDA 33543 (813) 535 3408 4

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FAST PHASE ANGLE ~ SUPERVISION FOR TP#lSMISSION LINE RECLOSING q.

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g oVERIFIES PHASE ANGLE IS WITHIN PRESET LIMITS WITHIN ONE CYCLE OFOR SYNCHRONOUS TRANSFER OF MOTOR BUS BETWEEN ' ALTERNATE SOURCES

{L o CLOSES ONLY IF LINE POTENTI AL VOL TAGE IS WITHIN ADJUSTABLE LIMITS v o' - 4 c'n t.

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HIGH SPEED SYNC-CHECK RELAY N-0245 APPLICATION e

High speed transfer of auxiliary services at a generating plant or

• the mo to r load in an industrial plant is highly desirable to prevent e i the r damage to cri ti cal' motors or an unplanned shutdown.

A significant induced vol tage will remain a t the terminals of a

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rota ting machine for a period of time following removal of power.' i f, during the p owe r. t rans fe r sequence,- the pha se angle of this voltage rela tive to _the auxiliary source is ignored, severe damage to an expensive mach.ine: orJprocess may resul t.

The M-0245 High Speed Sync-Check Relay provides the means necessary to inhi bi t transfer if the phase angle is excessive.

This device can also be used as a permissive relay in the fast (closingofa.transmissionbreaker.

SPECIFICATIONS

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RESPONSE TIME:

o Delay af ter power turn on:

aprox.3 seconds.

Output will be open during this period'regardless.of other inputs.

oDelay after closing enable input:

h cycle.

Output will be open un til unit is ena bled regardless of other inputs.

oDelay to change in voltages in and out of band is given by a set o f g raphs and generally ranges 0 to 1 second.

o Maximum delay after phase change i n or. ou t of band:

one cycle.

INPUTS:

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oBus Potential, 120 V ac nominal 0.15 V A bu rden.

o Line Potential, 120 V. ac nomina l 0.15 V A bu rden.

oH-024'S Supply, 120 V ac 10%, 12 VA bu rden, 60 to 400 Hz.

o Exte rna l dry contact cl osu re to enable the synchronizing ve ri fica tion.

This may be an auxil ia ry "b" contact of the main bus breaker.

OUTPUTS:

o Solid s ta te Breaker Close Circuit is capable of making and breaking an inductive current of 15 amps at 300 V dc.

Closing signal will remain un ti l enable contact is opened, provided phase angle and voltage remain within preset limits.

o Ana log data ou tputs a re provided for the following signals:

Auxiliary Source Voltage and Phase Difference.

Opera ti ona l status contacts for phase and vol tage cond i tions a re also provided.

These outputs are suitable for use with existing or future supervisory control systems.

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CONTROLS:

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1 oUPPER VOLTAGE LIMIT for Line Poten tial, range:

110 - 140 V ac.

o LOWER VOLTAGE LIMIT for Line Potential, ra n ge :

90 - 120 V ac.

o PHASE ANGLE LIMIT, range:

0 - i80*.

LED INDICATORS:

o UPPER VOLTAGE LIMIT OK:

Line Po ten ti al less than setting of '

Upper. Limit.

o LOWER VOLTAGE LIMIT OK:

Line Po t e n ti a l greater than. setting of Lewer Limit.

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oPHASE ANGLE LIMIT OK:..Line to Bus phase difference less than setting of Pha.sa. Angle Limit.

oREADY:

Unit rea'y.

Breaker will close i f vol tages and phase d

angle are'within control limit settings, and Ena b l e Con ta c t is closed.

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oENABLED:

External Ena bl e. Con tac t is closed.

. TRANSIENT PROTECTION:

o All voltage i n p'u t co nnec tio ns and solid state Breaker Close Circuit connections will withstand 2,500 V ac, 60 Hz to chassi s or instrument ground for 1 minute.

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oThese i npu ts will a l so withs tand the ANSI SWC Test (C37.90a-1974) and are designed to withstand the Fast Transient Test.

o All inputs and outputs are el ec tr i ca l ly isola ted from each other.

RELIABILI TY:

The H-0245 High Speed Sync-Check Relay is assembled on a single glass-epoxy printed circuit board thereby elimina ting the need for plug-in conne c to rs.

All semiconduc tor componen ts are hermetically sealed and 9

of the h i ~g h e s t and most reliable. quality available.

Highly stable instrument grade capaci to rs and* res is tors are used in critical measurement circuits to minimize the possibility of error.

PHYSICAL:

oSize:

19" wide by 3i" high by 13" deep (48.26 cm X 8.89 cm X 33.02 cm).

Requires two rack units space in a standard 19" rack.

May also be panel mounted horizon tally or vertically.

o Weigh t:15 lbs.

(6.75) kg).

oShipping Weight:

20 lbs.

(9 kg).

oTemperature Range:

Unit will operate properly over a tempe ra tu re range of -40 to +80 C.

These abbreviated speci f ica tions should not be used for detailed q

appl i ca tion.

Please con tac t Beckwi th El ect ric Co. for complete I n f o rma't i on and applica tion assis tance.

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1101162ND STREET NORTH LARGO, FLORIDA 33543 (813) 535 3408 PRINTED IN U.S.A.

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