ML17046A450
Text
8.3 ONSITE POWER SYSTEM The description in this section is on a unit basis.
identical in configuration and differ only in nomenclature.
Units 1 and 2 are The Onsite Power System for each unit consists of the various Electrical modes of to reliable electrical power during all and shutdown conditions.
The have been with sufficient power sources, redundant provide reliable electrical 9ower.
and required switching to A one-line diagram of the station's Onsite Power System is shown on Figure 8.3-1, which indicates that power to supply the station electrical requirements is available via the station power transformers and the auxiliary power transformer.
The Offsite Power in combination with the Onsite Power has been shown by analysis and test to possess sufficient capacity and capability to automatically start and subsequently operate all safety loads within their voltage ratings for anticipated transients and accidents. The worst sustained undervoltage condition in the Onsite Power System vital buses, while connected to the Offsite Power System with two 500/13 kV transformers supplying the vital
- buses, was found to occur with the 500-kV offsi te system at the minimum with a concurrent loss-of-coolant accident (LOCA) on Unit 2 while in Mode 1 and Unit 1 in Mode 3 (or vice versa).
This undervoltage condition results from the automatic transfer of the group buses from the auxiliary power transformers to the station power transformer and the automatic start of the required vital bus loads.
The 4160-V Undervoltage Protection System is described in Section 8.3.1.2.
8.3-1 SGS-UFSAR Revision 26 May 21, 2012
8.3.1 AC Power 8.3.1.1 Station Power and Auxiliary Power Transformers The 500-13 kV station power transformers are connected to different bus sections of the 500-kV switching station as indicated on Figure 8.2-2.
has the capacity to start both units at the same time.
Each The 13-kV north ring bus arrangement is shown on Figure 8.3-2.
Sectionalizing breakers in this ring bus are normally open and each 500-13 kV transformer Tl and T2 feeds two (one for each unit) 13-4 kV station power transformers Tll, T21 and Tl2, T22 associated with group buses.
The 13kV south bus arrangement is shown on Figure 8. 3-2a.
Each isolated section (A and D) of the bus is powered from 500-13kV transformer T3 and T4 respectively and feeds two, one for each unit, 13-4kV station power transformers Tl3, T24 and Tl4, T23 associated with vital buses and circulating water switchgear.
The 13-4kV station power transformers Tl3 and Tl4 (Unit 1) share the loads of three vital buses and two CW bus sections while T23 and T24 (Unit 2) share the loads of three vital buses and two CW bus sections.
The 13-kV bus arrangements assure a continuous preferred power supply to each unit in the event one 500-13 kV transformer should become inoperable.
The 25-4-4 kV auxiliary power transformer primary side is connected to the generator isolated phase bus.
Each of the two 4-kV secondary windings is connected to two 4160-V group buses.
8.3.1.2 4160-Volt System The 4160-V system is divided into four group bus sections, three vital bus sections and two circulating water bus sections as shown on Plant Drawings 203001, 203062, 203002 and 602939.
The group buses feed plant auxiliaries other than engineered safeguards equipment.
The group buses are energized by the 13-4 kV station power transformers during startup.
After the generator is synchronized to the 500-kV system, the group buses 8.3-2 SGS-UFSAR Revision 27 November 25, 2013
are manually transferred to the 25-4-4 kV auxiliary power transformer.
Should a unit trip, each 4160-V group bus automatically transfers from the auxiliary power transformer source to the station power transformer source.
The vital buses are fed directly from 13-4kV station power transformer T13, T14 (Unit 1) and T23, T24 (Unit 2). During normal operation, two of the vital buses are supplied from one station power transformer and the third from the other station power transformer. station power transformers Tl3, Tl4 (Unit 1) and T23, T24 (Unit 2) are also power source for two sections of cw switchgear.
The tie breaker between these sections is normally open.
The in-feed breakers on each vital bus from the two station power transformers are electrically interlocked to prevent paralleling both sources through a vital bus. These in-feed breakers provide means for transferring between sources in the event of an interruption of power from one source. Control power for each of the three 4160-V vital buses is provided by a normal feed from one battery and an emergency feed from another battery through two manually-operated, mechanically-interlocked molded case circuit breakers. Each 4-kV vital bus provides power to a 460-V and 230-V bus.
There are no interconnections between the redundant 460 or 230-V vital buses.
In the following discussion, component numbers for Unit 1 are used.
The functional description applies to Unit 2 as well.
The 4-kV vital buses are normally energized from either No. 13 or No. 14 station power transformer through in-feed breakers 13ASD, 13BSD, 13CSD or 14ASD, 14BSD, l4CSD.
In the event the normal source to a 4-kV bus becomes unavailable, that bus can be automatically transferred to its alternate source, provided the following conditions are met (assume No. 14 transformer is the normal source for vital bus lA) :
- 1.
lA bus differential or overload relays have not operated. Voltage on the bus is below a predetermined value.
Breaker 14ASD is open.
8.3-3 SGS-UFSAR Revision 15 June 12, 1996
- 2.
l.AJ)Jl breaker (diesel generator) is open.
No.
13 station power transformer is energized.
SBC bus undervoltage relay has not operated.
In the event all offsite power is lost, the standby diesel generators are automatically started and the normal in-feed breakers to each 4-kv vital bus are opened.
When the diesel generator is up to speed and voltage, its generator breaker is closed to energize that 4-kV bus.
An interlock from the diesel generator breaker prevents closure of either in-feed breaker to that bus, thereby preventing any interconnection between redundant 4-kv buses.
The above controls and interlocks are in conformance with the provisions of Regulatory Guide 1.6.
undervoltage protection on the 416o-V vital buses is provided in two levels as described below.
The first level uses undervoltage relays to sense the loss of offsite power.
These relays monitor the 416Q-V vital buses.
When the voltage on these buses drops below 70 percent of its rated voltage, the undervoltage relays drop out.
The drop-out action of the relays isolates the buses from the offsite sources, and initiates the SBC to accomplish safeguards loading.
The Second Level Undervoltage Protection System (SLUPS) is comprised of three under voltage and time delay relays per vital bus which react after the voltage at the vital bus drops below the setpoint of 95.1 percent (94.61 by technical specifications, the difference is relay calibration range) of rated voltage and does not recover to the relay reset setpoint for a period of 13 seconds.
Each SLUPS relay operates an auxiliary relay which provides an input to the undervoltage relays associated with the vital bus Safeguards Equipment controller (SBC).
The SBC utilizes this input to provide 8.3-4 SGS-t1PSAR Revision 16 January 31, 1998
/
a two-out-of-three relay intelligence to separate the vital bus from the offsite power source and load it onto its associated emergency diesel generator.
One of these SLUPS relays will also operate the vital bus 70-percent auxiliary relays (one for each SEC) to provide a two-out-of-three bus undervoltage intelligence similar to the 70-percent protection scheme.
A failure for each component in the That demonstrates that no failure will result in the creation of an unanalyzed condition.
This configuration:
- 1.
Eliminates the possibility of vital bus flip-flopping.
- 2.
Provides for separation of the vital buses from the preferred source on an individual basis only.
- 3.
Satisfies GDC-17 relative to the connection between the offsite source and the onsite distribution system, as clarified in the following paragraphs.
Two situations exist whereby a single vital bus could be separated from its offsite source (SPT) when the offsite source is operath1g within expected limits.
The first case occurs as a result of failure of the relay providing the No.
1 input to the affected SEC, coincident with a LOCA This is j
to be on the following bases:
- 1.
The affected vital bus is automatically loaded onto its emergency source and is available for accident mitigation.
- 2.
The separation occurs only as a result of a failure of the relay providing the No. 1 input to the SEC.
The second case occurs as a result of a such that its output is less than the 8.3-5 SGS-UFSAR Revision 22 May 5, 2006
- SPT,
of the second level undervoltage system but greater than the of the primary undervoltage system.
This unlikely condition would have to occur to the SPT supplying power to two of the three vi tal buses.
For this scenario, the second level undervoltage system would operate as designed, such that after 13 seconds the affected buses would be separated from the offsite source and loaded onto the emergency source.
However, sufficient time exists
(~13 seconds) between the from the preferred source and the sequencing of the bus onto the emergency source to allow operation of the primary undervoltage system.
The primary undervoltage system would sense a loss of power to the affected buses and, upon completion of its two-out-of-three bus logic, cause the remaining vital bus (supplied from the alternate SPT) to be separated from the preferred source.
This condition reasons:
- 1.
Expected failure mechanisms for this type of transformer result in complete loss of secondary voltage.
- 2.
The scenario described above only occurs when the degraded transformer is providing power to two of the three vital buses.
Since only one of the two SPTs per unit can be loaded in such a
- fashion, the of an invalid occurring is further reduced.
- 3.
In the unlikely event that this condition should occur, the bus which is separated from the functioning SPT is loaded onto its emergency source, thereby ensuring its availability in the event of an accident.
It should also be noted that the same scenario would occur if the PSE&G bulk power was below expected limits.
source is desirable for this condition.
\\
8.3-5a SGS-UFSAR from the offsite Revision 26 May 21, 2012
Except as previously discussed, the loss of offsite power to vital buses, due to spurious operation of the voltage protection relays, will not occur when the offsite grid voltage is within its expected limits and both 500/13 kV transformers are supplying both Units 1 and 2.
There is a possibility of spurious tripping occurring during minimum grid conditions if one transformer is supplying both units' vital buses.
The NRC Safety Evaluation Report dated October 21, 1981, which documents the NRC's review of Salem Station Units 1
and 2
adequacy of station electrical distribution system voltages, states that the incidence of spurious relay tripping in this case is dependent upon several events occurring simultaneously:
(1) the loss of a station power transformer, (2)
Loss of coolant accident on one unit, (3) shutdown of the other unit, (4) grid voltages at minimum expected value, and (5) rate of change of grid voltage exceeding the response time of the self regulating transformer.
The NRC staff states that the probability of all of these events occurring simultaneously is very low and the consequences of such an occurrence would be a
safe unit shutdown.
Therefore, the NRC staff concludes that the incidence of spurious tripping is insignificant and Position 3 of the August 8, 1979 letter is met.
The second level undervoltage trip setpoint of 95.1 percent is based upon the results of detailed analyses of the Salem Generating Station electrical distribution system transient response characteristics.
Those analyses indicate that, at the PSE&G bulk power system voltage minimum expected value and for a LOCA on one Salem unit, concurrent with the other unit in Mode 3, vi tal bus voltage will recover to a worst-case value of r::::97 percent.
The minimum allowable trip value and trip setpoint are derived using the 90-percent minimum motor terminal voltage requirement as a
starting point and then applying appropriate allowances required by Regulatory Guide 1. 105.
Specific motor loads not meeting the 90-percent criteria are analyzed to demonstrate the ability of those motor loads to fully meet their design function without tripping their protective devices or exceeding their thermal capabilities.
Group bus undervol tage protection ( 68 percent of nominal) will automatically trip the reactor coolant and condensate pump 4-kV breakers upon sensing an undervoltage (i.e., loss of voltage) condition on its respective 4-kV group bus (1E, 1F, 1G, and 1H) using 1/1 logic taken once.
8.3-5b SGS-UFSAR Revision 27 November 25, 2013
8.3.1.3 460- and 230-Volt Systems The 460-V Auxiliary System feeds most motors from 20 to 300 hp.
The 230-V System feeds smaller loads and, for convenience of operation, a
few motors larger than 15 hp.
The 4160-V System feeds the 460-V and 230-V systems via 4160-460-V and 4160-240-V transformers.
The 460-V and 230-V Vital Bus Systems are divided into three bus sections which correlate to their respective 4160-V vital buses.
8.3.1.4 115-V ac Instrumentation Power Four 12-kVA 115-V ac vital instrument buses (1/2 A,B,C & D) receive power from individual Uninterruptible Power Supplies (UPS) to form redundant channels for reactor control and protection instrumentation and safety-related equipment.
Each vital instrument bus UPS's Rectifier receives normal source, vital 230-V ac power, converts (rectifies ac/dc) it to de power, and then converts (inverts dc/ac) it to ac power.
In the event of a 230-V ac power loss or an UPS's Rectifier malfunction, 125-V de vital station battery power will automatically supply power to the UPS's Inverter, via the UPS's auctioneering circuit, to maintain uninterruptible ac output power.
Each UPS also contains a
12-kVA ac Line Regulator and Static Switch that receives alternate source, vital 230-V ac power from the same normal source vital 230-V ac bus.
In the event of an UPS's Inverter malfunction, the Static Switch senses a
loss of Inverter output voltage and automatically fast transfers the associated vital instrument bus loads to the ac Line Regulator 115-V ac output.
When the UPS's Inverter voltage returns to normal, the Static Switch will automatically return the associated vital instrument bus loads to the Inverter output.
Table 8. 3-1 depicts channel designations for each vi tal instrument bus power feed.
The 115-V ac Control Power System for Units 1 and 2 is illustrated on Plant Drawing 211370.
SGS-UFSAR 8.3-6 Revision 27 November 25, 2013
8.3.1.5 Standby Power The ac power source consists of three diesel generators.
Each diesel generator set power to one 4160-V vital bus in the event of a loss of offsite power.
The system is shown on 8.3-1.
The nameplate continuous rating of the diesel generator units is 2600 k\\I'J1 900
- rpm, 4160-V, 3 phase, 60 cycles.
The units are sized to handle the loads necessary for a design basis LOCA coincident with the loss of all offsi te power.
The diesel generators are designed to be ready to accept load within 13 seconds after of a to start.
The diesel 100 feet.
units are located in the
\\.Vi thin the the at Elevation are isolated frorr. each other and from other equipment in the area by fire walls and fire doors.
An Automatic Fire Protection System is installed for the protection of the C02 diesel generator equipment.
Separate detectors are located in each compartment so that only the area containing the fire is blanketed.
The two 30, 000-ga.ll.on Elevation 84 feet.
fuel-oil storage tanks are located below the diesels at Each diesel generator has its own fuel oil day tank with a The tank is mo~nted above the unit for feed of fuel at startup.
Each diesel unit has its own lube-oil jacket
- cooling, and dual air starting system. Cooling water is by the Service Water System.
Any two of the diesel generators and their associated vital buses can supply sufficient power for operation of the required safeguards equipment for a
design basis LOCA coincident
\\.-Jith a
Sufficient
- o the vital is in the buses so that failure to of the minimum SGS-UFSAR features and their 8.3-7 Revision 25 October 26, 2010
In addition to the emergency diesel generators, there is a gas turbine generator installed at the site. This unit is rated at approximatel~O MW and is normally used for peaking purposes.
The gas turbine unit is connected to the auxiliary electrical system such that it can be paralleled with the normal source of plant startup or standby power.
Figure 8.3-2 shows the gas turbine connection to the 13-kV ring bus system.
8.3.1.5.1 Diesel Generator Capacity and Loading Each diesel generator unit is rated as follows:
TIME KW PF KVA.R KVA.
1/'2 HR
- £3100 0.8 2325 3875 2 HRS
- £2860 0.8 2145 3575 2000 HRS
,5.2750 0.8 2063 3438 CONT
- E-2600 0.8 1950 3250 A detailed loading study (Calculation ES-9.002[Q)) has been performed for the diesel generator units based on the following:
- 1)
Design basis Loss of Offsite Power Accident (LOPA).
start successfully.
All three D/G's
- 2)
Design basis Loss of Coolant Accident {LOCA) coincident with Design Basis LOPA.
All three D/G's start successfully and experience worst case active single failure.
- 3)
Design basis LOCA coincident with Design Basis LOPA.
failure analyzed is one (1) D/G failing to start.
Active single Conclusions of this study indicate tha~ for the above mentioned scenarios, all expected loads are within the Diesel generator ratings as given
~bove. ~
Furthermore, the study also confirms that the auto connected loads do not exceed the short time rating (2 Hour) as defined in Regulatory Guide 1.9 Rev. 2 and IEEE STD 387 1977.
Tables 8.3-2 and 8.3-3 indicate the timing and sequence in which the loads are a~~omat~cal~y connec~ed to the D/G's
- o~ the LOP~ only and LOCA
+LOPA cases.
In the event that the D/G loading requires revision, the changes will be evaluated to verify that they are enveloped by the worst case transient load (Service water pump start) and therefore do not result in unacceptable voltage and frequency responses, consistent with the intent of Regulatory Guide 1. 9 Rev. 2.
8.3-8 SGS-UFSAR y...
Revision 14 December 29, 1995
In addition to prototype tests conducted in the manufacturer's plant, testing has been performed at the station to simulate the various modes of These tests verified that the fied diesel load criteria have been met.
The diesel generators have the capability to attain rated within 13 seconds after receipt of the start signal, 8.3-Ba SGS-:JFSAR and Revision 25 October 26, 2010
SGS-UFSAR THIS PAGE INTENTIONALLY LEFT BLANK 8.3-Sb Revision 12 July 22, 1992
in Tables 8. 3-2 and 8. 3-3.
The and to accept load Loading Control in the sequence shown will automatically eneralze the required loads within 35 seconds.
that credit the assume start and load well as any value fied by Technical of the diesel generators that bound these values as The Safeguards Equipment Control (SEC) the diesel generators, is described controller in each train (A, B, and C) bus in that train.
System, which controls the loading of in Section 7.
Control power for the is supplied from the 115-V ac instrument 8.3.1.5.2 Diesel Generator Control and Functions The diesel are started automatically by the ection signal or indication of a loss of all offsi te power to the 4160-V vi tal buses.
The latter signal, determined using 2/3 logic, initiates the loading sequence for each vital bus.
The loading sequence trips the vital bus in-feed breakers and all motor feeder breakers, closes the diesel generator breaker after the unit comes up to its speed and voltage permissive set points, and connects the sa loads in a predetermined sequence.
The sequence for each vital bus is separate and of that for the other buses.
The diesel generator sequences under emergency conditions are discussed in Section 7.
Following an am::omatic start (by loss of normal auxiliary power or by an accident signal), the follm-;ing automatic protective devices are in service during emergency startup and operation of the diesel generator:
- 1.
SGS-UFSAR Shut down the diesel generator and breaker due to:
- a.
Mechanical l)
Engine overspeed
- 2)
Lube oil pressure low 8.3-9 the diesel generator Revision 25 October 26, 2010
- b.
Electrical
- 1)
Generator differential current relays
- 2.
Trip the diesel generator breaker only due to:
- a.
Electrical
- 1) 4 kV bus differential Manual diesel generator control is provided as follows:
- 1.
on the local diesel generator control panels; Diesel generator "START-STOP" pushbutton, "LOCK-OUT" switch selector switch.
selector switch, "EMERGENCY STOP" (key operated)
"AUTO-MANUAL" mode Diesel generator breaker "TRIP -
CLOSE" selector switch Generator voltage "RAISE -
LOWER" control switch Speed.. RAISE -
LOWER" control switch Regulator "MANUAL -
AUTO" switch Diesel unit trip relay "RESET" Fuel transfer pump "OFF -
AUTO -
RUN" selector switch, "REGULAR -
BACKUP" selector switch Starting air compressor "OFF -
AUTO -
RUN" selector switch Turbo air compressor "OFF -
AUTO -
RUN" selector switch
- 2.
In the Control Room:
8.3-10 SGS-UFSAR Revision 6 February 15, 1987
Diesel generator *sTART-STOP* pushbutton&, *CLOSE -
TRIP*
puahbuttone.
Following a manual start, the following automatic protective devices are in service during startup and operation of the diesel generator:
- 1.
Shut down the diesel generator and trip its 4-kV circuit breaker due to:
- a.
Mechanical l)
Engine overapeed
- 2)
Lube oil pressure low
- 3)
Jacket water temperature high
- 4)
Lube oil temperature high
- 5)
Engine overcrank
- b.
Electrical
- 1)
Generator differential current relays
- 2)
Loss of generator excitation
- 3)
Diesel generator breaker failure protection
- 2.
Trip the diesel generator breaker only due to:
- a.
Electrical
- 1) overcurrent relay
- 2)
Reverse power relay 8.3-11 SGS-UFSAR Revision 6 February 15, 1987
- 3.
Prevent the Diesel Generator Circuit Breaker from closing only
., due to:
- a.
Electrical
- 1.
Syncrocloser check relay; the syncrocloser check relay provides a permissive to allow the operator to synchronize the Diesel Generator with ita vital bus.
The permissive will be enabled during a specific closing phase angle range, slip limit (AF limit), voltage range, and blocked when out of these ranges and when the breaker control switch at the Diesel Generator Control Panel is intentionally held closed prior to achieving syncpronization.
Elimination of trips could cause damage to the diesel generators if a trip condition were to occur.
8.3.1.5.3 Diesel Generator Instrumentation To facilitate control and adjustment of the diesel generators, the following instrumentation and alarms are provided.
- 1.
controls on the local diesel generator control panels:
SGS-UFSAR.
Generator ammeter (with phase selector switch), wattmeter, voltmeter (with phase selector switch),
frequency meter, varmeter, field ammeter, field voltmeter, synchroscope, synchronizing lights, eynchroscope switch, 4 kV bus voltmeter (with phase selector switch), diesel generator running time meter, RPM meter Jacket water pressure gage Raw water pressure gage Fuel oil header pressure gage Fuel oil transfer pump pressure gage 8.3-12 Revision 14 December 29, 1995
SGS-UFSAR Air manifold pressure gage Starting air pressure at engine {duplex gage)
Starting air tank pressure (duplex gage)
Turbo air tank pressure (two duplex gages)
Jacket water heat exchanger differential pressure (duplex gage)
Lube oil filter differential pressure (duplex gage)
Lube oil strainer differential pressure (duplex gage)
Fuel oil primary filter differential pressure (duplex gage)
Fuel oil secondary filter differential pressure (duplex gage)
Lube oil header pressure Lube oil pump discharge pressure Lube oil heat exchanger differential pressure Revision 13 June 12, 1994
THIS PAGE INTENTIONAllY LEFT BlANK 8.3-12b SGS-UFSAR Revision 13 June 12, 1994
- 2.
Controls in the Control Room:
Diesel generator voltage, frequency, watts, amps.
- 3.
Alarms local to the diesel generator:
following:
SGS-UFSAR Cooling water temperature low Cooling water temperature high Jacket water temperature high Jacket water heater failure Lube oil temperature high Lube oil heater failure Fuel oil day tank level low Expansion tank level high crankcase level high/low Engine lube oil header pressure low Fail to start (overcrank}
Diesel generator tripped Generator negative phase sequence Fuel oil day tank level high Pre-lube pump failure Crankcase blower failure Exciter regulator on manual control Diesel generator locked out (for maintenance)
DC control voltage failure-a single alarm to include the Loss of de power to the engine control Loss of de power to the generator field Loss of de power to the unit trip circuit Loss of de power to the local alarm system Air receiver No. 1 pressure low Air receiver No. 2 pressure low Generator breaker trip Generator field ground 8.3-13 Revision 16 January 31, 1998
I Expansion tank level low Generator overspeed Generator overvoltage Generator loss of PT secondary voltage Generator ground fault Turbo air receivers low pressure
- 4.
Alarms in the Control Room:
SGS-UFSAR Diesel generator trouble (a common alarm which will be actuated by the operation of any of the above local alarms).
Diesel generator urgent trouble-a single alarm to include the following:
Jacket water temperature high Lube oil temperature high Engine lube oil header pressure low Air receiver pressure low Pre-lube pump failure Generator ground fault Turbo air receivers low pressure Fuel oil day tank level trouble (a common alarm for all three unit day tanks).
Loss of de power to the engine control, generator field, trip circuits.
Diesel generator in Local-Manual control mode, failure to start, emergency trip, locked out.
Generator breaker spring charger failure, breaker trip.
- 8. 3-14 Revision 18 April 26, 2000
8.3.1.5.4 Diesel Generator Support Systems Diesel Generator Support Systems are desclibed in the following sections:
Fuel Storage and Transfer System Jacket Water Cooling System Starting Air System Lube Oil System 8.3.1.6 Tests and Inspections Section 9.5.4 Section 9.5.5 Section 9.5.6 Section 9.5.7 Periodic tests will be conducted to ensure proper operation of electrical features necessary for plant safety.
Tests will be conducted to identify and correct electrical or mechanical deficienci~s before they result in a system failure.
Tests will be conducted periodically to verify the starting of the diesel generators on loss of voltage to the 4160-V vital buses and their ability to carry load.
The standby ac power sources (diesel generators) are automatically started and connected to the vital buses 1n the event the normal offsite sources become unavailable.
The standby diesel generators are automatica!ly started by eLther a safety injection signal or a 2-out-of-under~o:tage signal derived from under~oltage relays located on the three 4-kV vlta buses.
Testability of each of these signals LS provided.
The Solid State Protection System (SSPS) test cabinet is used to check the continuity of the SSPS output relay contact, the field wiring, and the Safeguards Equipment Controls (SEC) input relay without actually operating the SEC unit.
The undervoltage relays can be tested by operating test switches to simulate a single bus undervoltage condition.
During the test mode an alarm is actuated in the Control Room signifying that diesel generator automatic start is defeated.
8.3-15 SGS-UFSAR Revision 6 February 15, 1987
Since the SEC units are completely independent of each other, the SSPS test cabinets are used to provide independent output signals from both SSPS trains to the three SEC units.
Buffer relays are used on each vital bus undervoltage sensor to supply independent signals to each SEC unit. Thus, complete channel independence is maintained.
The SEC units are completely redundant.
Both SSPS trains feed each SEC; a
failure of an SSPS train will not negate safeguards operation.
Failure of a bus undervoltage relay to operate will not negate safeguards operation since a 2-out-of-3 undervoltage logic is used to sense loss of offsite power conditions.
If only one bus experiences undervoltage, and the sensor on that bus fails to recognize the condition, only that bus will not be loaded; the remaining buses will supply power to the required amount of safeguards equipment.
The diesel generators can be started and loaded during power operation. As discussed above, the 4-kV bus undervoltage relays can also be tested during power operation.
The complete operation of detecting the loss of normal power sources, starting of the standby power sources, and connecting these sources to the vital buses can be accomplished during plant shutdown.
These design provisions satisfy General Design Criterion 18.
8.3.2 DC Power 8.3.2.1 250-, 125-, and 28-Volt Systems Separate 125-V and 250-V de sources supply power for operation of switchgear, annunciators, vital instrument
- buses, inverters, emergency
- lighting, communications, and turbine generator emergency auxiliaries. Three independent 125-V de sources provide power to the engineered safety features.
Plant Drawings 211357, 203007, 223720 and 203008 illustrate the 28-V, 125-V, and 250-V station de systems, SGS-UFSAR 8.3-16 Revision 27 November 25, 2013
respectively.
Safety-related loads are identified by the use of the symbols A, B, C, D on the feeders.
Battery load profiles are shown in Tables 8.3-5 and 8.3-6.
As shown on Plant Drawings 203007 and 223720, three 125-V batteries are provided for each unit to supply an independent source of control power for each of the three 4160-V and 460-V vital buses and for the 125-V distribution cabinets.
A backup source of control power for each of these buses is provided via manually operated breakers under administrative control.
The station de systems provide a continuous source of power for operation of circuit breakers, valve controls, inverters, etc.
No initiation or control is required to connect the batteries to the de buses.
Two separate non-safety related 125-V de batteries have been provided to serve the 4160 V CW switchgear, 13 kV south bus section breakers, SCADA systems and portions of switchgear relaying systems.
8.3.2.2 Station Batteries The Station Battery System includes one non-vital 250-V, three vital 125-V, and two vital 28-V batteries, static battery chargers for each battery, and a ground detection system and undervoltage alarm relay for each bus.
The batteries are mounted on corrosion-resistant, seismically designed steel racks in separately ventilated and isolated areas.
The 250-V, 125-V, and 28-V batteries are rated 1326, 2320, and 800 ampere hours, respectively, at the 8-hour rate of discharge.
Each charger maintains a floating charge on its associated battery, and is capable of supplying the required equalizing charge when necessary. Each 125-V and 28-V Battery System (one battery, two chargers, and one switchgear unit) has a ground detection system, undervoltage alarm relay, and de voltmeters and ammeters.
Each 28-VDC charger is equipped with an ac failure relay.
Loss of ac input and/ or de output is annunciated in the Control Room.
Each Unit 1 125-VDC battery charger is equipped with a loss of AC voltage alarm.
Each Unit 2 125-VDC charger is equipped with a summary trouble alarm which indicates AC Power Failure, High Voltage Shutdown, No Charge and High/Low Voltage.
Alarms from both Unit 1 and Unit 2 battery chargers are printed in the Control Room.
Each 125-VDC battery is connected to its associated switchgear through a
disconnect switch and protective fuses.
The 250-V AND 28-VDC batteries are connected to their associated switchgear through protective fuses.
distribution switchgear consists The de 8.3-17 SGS-UFSAR Revision 27 November 25, 2013
of metal-clad structures, each with an ungrounded main bus, and 2 pole air circuit breakers.
During normal operation, the de load is fed from the battery chargers with the batteries floating on the system.
Upon loss of de power from a battery charger, the de load is drawn from the batteries.
The batteries are sized for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of operation after a loss of ac power, based upon the required operation of the de emergency equipment.
If all offsite power is lost, the battery chargers are energized from the emergency diesel generators and resume their function automatically.
8.3.2.3 Station Battery Monitoring Two chargers, each capable of 100-percent normal load, are provided for each 28-V and 125-V de battery.
Each normal charging source supplies the continuous de loads and maintains a float charge on the battery to ensure the capability of each battery to deliver its emergency de requirements.
The 28-V and 125-V chargers are fed from the vi tal ac buses.
Each 28-V and 125-V battery is fed from two separate vital buses.
One charger is under administrative control to assure that the 230-V ac buses will not become interconnected.
One 250-V de charger is provided due to the nature of the 250-V de loads, with a provision to tie in the other unit's 250-V charger, if needed.
Each of the 6 batteries per unit is continuously monitored in the Control Room for voltage and discharge current.
Listed below are all the monitoring devices associated with each battery.
A brief description of the function of each device and its location is given.
Battery Voltmeter -
Monitors de bus voltage with continuous readout in the Control Room.
8.3-18 SGS-UFSAR Revision 14 December 29, 1995
Battery Load Ammeter -
Monitors discharge current with continuous readout in the Control Room.
Ground Detectors Monitors leakage from positive and negative buses to station ground with continuous readout in the Control Room.
In addition, local ground detection circuit is provided adjacent to each charger for test purposes.
Undervoltage Alarm -
Monitors each de bus and alarms in the Control Room when bus voltage drops below a preset value.
Charger Voltmeter - Monitors charger output voltage at charger cabinet.
Charger Alarm -
Monitors ac input to charger and alarms in the Control Room upon loss of input voltage to both 28-VDC chargers.
Each Unit 1 125-VDC battery charger is equipped with a loss of AC voltage alarm.
Each Unit 2 125-VDC battery charger is equipped with a charger trouble relay which provides a summary alarm in the Control Room if the energized charger experiences an AC power failure, high voltage shutdown, no charge or high/low voltage.
The 250-VDC chargers also have an overvoltage alarm in the Control Room should the bus voltage rise above a preset value.
DC Distribution Cabinet Undervoltage Alarm Each 28-V and 125-V de distribution cabinet is provided with an undervoltage relay which monitors bus voltage and alarms in the Control Room.
Blown Fuse Alarm -
Each battery fuse is monitored to alarm in the Control Room if the fuse should blow.
Protection against overcharging is provided within the charger itself which is a constant voltage-current limited device.
Surveillance requirements are set forth in the Technical Specifications.
The general cleanliness of battery, float charge, cell cracks, electrolyte
- leakage, ventilation equipment, c~ll to cell periodically inspected to assure good 8.3-19 SGS-UFSAR connections,
- etc, are Revision 16 January 31, 1998
service and long battery life.
- Thus, degradation can be monitore~ and rectified during surveillance and testing program.
8.3.2.4 CW Switchgear Batteries Each CW Switchgear Battery System includes one 125-V battery/
two static battery chargers, ground detection and metering cabinet.
The batteries are mounted on corrosion resistant steel racks in separate ventilated Building.
discharge.
and isolated Each battery areas located is rated 960 in the Circulating ampere-hours at the Water Switchgear 8-hour rate of Each charger maintains a floating charge on its associated battery, and is capable of supplying the required equalizing charge when necessary.
Each battery charger provides a charger failure alarm signal to the SCADA System.
The battery is connected to its associated 125-V distribution panel through protective fuses and a manual transfer switch.
The manual transfer switch allows either 125-V distribution panel to be switched to the other battery if its own battery is out of service.
During normal operation, the de load is fed from the battery chargers with the battery floating on the system.
Upon loss of AC power to the battery chargers and the P250 computer inverter, the battery can supply the full P250 inverter load of 15KVA for up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and the remaining DC loads for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
- 8. 3. 3 Containment Penetration/Conductor Overcurrent Protection The containment penetrations/conductors are protected by deenergizing circuits which are not required for reactor operation and by ensuring the operability of primary/backup overcurrent protective devices through periodic testing of equipment/systems.
The containment penetration/conductor overcurrent protection devices are listed in and controlled by Engineering Calculations Numbers ES-13. 010 (Q) and ES-13. 005 (Q) for Salem Units 1 and 2, respectively.
An integrated system functional test includes the simulated automatic actuation of circuit breakers to verify response times and trip setpoints.
8.3-20 SGS-UFSAR Revision 18 April 26, 2000