ML19340D385
| ML19340D385 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 12/22/1980 |
| From: | Baynard P FLORIDA POWER CORP. |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8012300481 | |
| Download: ML19340D385 (25) | |
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1,4;ggM" Power CO H PO# A f iO N December 22, 1980 File:
3-0-3-a-3 C
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(0 Mr. Robert W. Reid ihr L-Branch Chief MW4 E
j Operating Reactors Branch #4 2
CE Division of Licensing Q
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U. S. Nuclear Regulatory Commission
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Washington, D. C. 20555
Subject:
Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 Adequacy of Station Electric Distribution Systems Voltages
Dear Mr. Reid:
Enclosed is our revised copy of the CR-3 Electrical Distribution System Review Summary. This revision includes response to questions telecopied to our Mr. K. B. Baker in June 1980.
Should you have any questions concerning this matter, please contact this office.
Very truly yours, FLORIDA POWER CORPORATION Vn*A-era Patsy Y. Baynard Manager Nuclear Support Services Enclosure Lobo (M04)D1-1 Mr. Ailen Uddy cc:
l EG&G Idaho P.O. Box 1625 l
f General Office 3201 Thirty-fourth street soutn. P O Box 14042 st Petersburg. Florida 33733 e 813-866-5151 -
1 I
8 012300 NSl
t STATE OF FLORIDA COUNTY OF PINELLAS P.
Y. baynard states that she is the Manager, Nuclear Support Services of Florida Power Corporation; that she is authorized on the part of said company to sign and file with the Nuclear Regulatory Commission the information attached hereto; and that all such statements made and matters set forth therein are true and correct to the best of her knowledge, information and belief.
Lvld. Ybaunaul P U. Bdyhard Subscribed and sworn to before me, a Notary Public in and for the State and County above named, this 22nd day of December,1980.
, QugGC fl, k&;fa v: PU' 8 Notary Public Notary Public, State of Florida at large, My Commission Expires: May 29, 1984 Chisamore(Notary)(D12)
CR-3 ELECTRICAL DISTRIBUTION SYSTEM REVIEW
SUMMARY
REV. 1 l
November 18, 1980 l
1
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QUESTIONS ON ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM V0LTAGES 1.
"The adequacy of the onsite distribution of power from the offsite i
circuits shall be verified by test te dssure that analysis results are I
valid."
i The following verification test will be performed to verify the calcu-lations made to determine various bus voltages:
With CR-3 on line and above 50% load and with auxiliaries con-t nected in the normal operation mode, the 230 kV grid voltage will I
be varied by the FPC system dispatch and/or by Crystal River Unit 1 & 2 generator controls to a maximum of 243.6 kV and to a mini-i mum of 236.4 kV.
Each level will be maintained sufficiently long l
enough for CR-3 plant personnel to record bus voltages on the i
plant auxiliary buses and ES buses.
Recorded voltages will be compared to calculated voltages to determine accuracy of the cal-culations.
2.
" Review the electric power systems of your nuclear station to deter-mine if there are any events or conditions which could result in the simultaneous or consequential loss of both required circuits to the offsite network to determine if any potential exists for violation of GDC 17 in this regard."
- A review of the Crystal River Unit 3 power system has been made and there are no events or conditions which could result in the simulta-neous or consequential loss of both circuits to the offsite network i
(230 kV substation) and no potential exists for any violation of GDC 17 in this regard.
3.
" Supply the calculated voltages for all low-voltage AC (less than 480V) Class 1E buses (including alternate sources) for each analyzed case.
Do these systems supply any instruments or control circuits as required by GDC 13?
If so, is all the equipment capable of sustaining the analyzed voltages without blowing fuses, overheating, etc. and without affecting the equipment's ability to perform the required function?"
- Crystal River Unit 3 has an essential 120 volt AC system for supply-ing vital instrumentation and control loads.
This system is designed as a non-interruptible power source using separate dual input static inverters backed up by the station battery system.
Voltage is main-tained at 12% and if normal sources from the engineered safeguard I
supply exceed voltage regulation of 110% automatic transfer to the l
D.C. battery source occurs.
The inverters may be shut down for main-tenance and essential 120 VAC can be supplied by regule.cing trans-l formers which will maintain near constant voltage (11%)for a variance of input voltage of 115 percent.
Presently this system may only be switched in by a manual switch.
Therefore, variations in the voltage levels of the offsite network will not affect the voltage levels of l
the essential 120 volt vital buses.
i
120V control voltage is used on the engineered safeguards motor con-trol centers. This voltage is obtained via control power transformers in each MCC cubicle.
The worse case voltage variation as determined by the requested calculations, was for MCC-ES 3A1, 3A2, and 382 for the case of backfeeding the Unit 3 auxiliary transformer from the Unit 3 step-up transformer at minimum plant loading (conditions during refueling).
For the subcase of system voltage at minimum during the dynamic state - 480V bus voltages weuld be.88591 pu.
The control power in these MCC would be at 88.59%. This worse case is not suffic-ient to cause starter coils to drop out (coils will withstand a vol-tage drop of 55% rated voltage for 2 seconds) and is not low enough to l
l cause blown fuses from reduced control voltages inducing overcurrent.
The starter coils are rated for pickup at 90% rated voltge as per NEMA Standard ICS2-1978.
As mentioned above, the worst case voltage con-dition on the ES MCC's was for the case of backfeeding the unit auxiliary transformer from the step-up transformer at minimum plant f
loading conditions (Table 6) and the dynamic condition with voltage at l
minimum system conditions could produce voltages of 84.9% of nameplate values.
It is felt that this condition does not present a serious problem for the following reasons:
1.
This condition only exists during the dynamic condition of start-ing the largest safety-related motor.
The steady state value is 87.2%.
I l
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2.
The NEMA standards actually are for 85% pickup and 90% pickup when a control power transformer is used.
On Crystal River 3, oversized control power transformers are used which should limit the effects of coil burden on reduced voltage.
4.
" Compare the effects of starting and running the largest non-Class IE load on all Class 1E buses and loads with the required voltage range for normal operation of these Class 1E loads (starters, contactors, motor ratings, etc.) for each available connection of offsite power.
What are the bus and load voltages when starting the largest 480V Class 1E load when all Class 1E buses are otherwise fully loaded?
What are the voltage profiles of these transient conditions?"
- Tables 1, 2, 3 and 4 (attached) summarize the calculation results for starting the largest Class IE load and starting the largest non-Class 1E load for the Unit 3 startup transformer connection to the offsite network.
These calculations were done at the present tap setting (224,250V) and the nominal tap setting of 230,000V.
Based upon the results of these calculations, it will be necessary to change the tap setting to 230,000V as the voltage seen on the 480V buses under maximum system conditions would exceed the 10% plus rating on the 460V motors with the present tap setting.
The results of the calculation for the case of connection to the alternate source (Unit 1 & 2 start-up transformer) and starting a large non-Class 1E load are shown in Table 11.
For this calculation,
i the worse case condition was assumed to be the simultaneous starting of both 3500 HP Unit 1 ID fans with the transformer loaded as per the loads from the FSAR included in Attachment "A".
As seen in Table 11, there are no extreme voltage conditions for this case.
i Table 5 (attached) shows the voltages calculated for the case of con-l nected through Unit 1 & 2 transformer and starting the largest Class 1E load.
l As seen in Table 5, no extreme voltage conditions would exist for this case.
5.
"The FSAR indicates that by the use of disconnect links, the unit auxiliary transformer can be used as a connection to the offsite grid.
There are no identified limiting conditions of operation.- Per NRC Guideline la, this connection needs to be analyzed."
- This connection is only used during a unit outage as the generator must be disconnected from the isolated phase bus duct.
Table 6 lists i
the calculated voltages for this case.
As seen in these results, no i
excessive voltage variations would exist.
6.
"Your analysis of the use of the Unit 1 & 2 startup transformer did not describe the Unit 1 & 2 loading of the transformer as required by NRC Guideline 13. Provide these assumptions."
_ = _ _..
- The unloading on the Unit 1 & 2 startup transformer is in terms of load from Units 1 & 2 was taken from the FSAR paragraph 8-2.3.1.d, page 8-10a, which is attached.
1 i
l 7.
"NRC Guideline lla requests a determination be made of "the maximun voltage expected at the terminals of each safety load and its starting circuit", assuming the maximum expected grid voltage and minimum plant loading.
Reference (e) does not provide this analysis.
Supply this information.
Note that your response to 1.db indicates that the no-load voltage can be as high as 4480V and 517V on the 4160V and 480V buses, respectively.
This is in excess of the +10% of nominal voltage rating and indicates that corrective measures are needed."
- Tables 7 and 8 (attached) show the results of the calculations for the existing tap setting on the Unit 3 startup transformer (224,250) and the proposed new tap setting (230,000).
Note that the pu values are in terms of voltages at nameplate rating.
As seen by the values in Table 7, it will be necessary to change to the 230,000 tap setting (Table 8) to get the overvoltages under ten percent.
The engineering orders will be prepared to perform the tap change dur-ing the Fall 1981 refueling outage or during the next scheduled outage of sufficient duration.
8.
" Verify, per NRC Guidelines 10 and 12, that your undervoltage relays with 80% trip, will not spuriously separate the Class 1E buses from offsite power when the auxiliary loads normally power from the unit auxiliary transformer are transferred to the SUT.
l l
- It is proposed to keep the existing undervoltage relays at their present setpoint of approximately 55%.
It is further proposed that a second set of undervoltage relays be added to the 4160V ES buses.
i These relays would be solid state - instantaneous relays which would be set to trip at 90% voltage. A total time delay of 10 seconds would be used before the 90% voltage level would initiate transfer to the diesel generators.
The schedule for completing the engineering package for effecting this change would be approximately April 1,1981.
The actual equipment change could be performed during the refueling outage presently planned for Fall 1981, provided equipment deliveries could be met.
The existing undervoltage scheme will still be used for initiating a dead bus transfer to the diesel generators.
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9.
"Page 80, indicates the 480V buses and MCC's do not have sufficient i
l voltage for continuous operation of the Class 1E loads.
Per NRC Guideline 9a, FPC should provide imediate remedial action and imediate notification of the NRC.
What is the FPC proposed remedial action?"
i l
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- Revised calculations, as seen in Table 5, indicate that this condi-tion would not exist. For the case of operation on the Unit 1 & 2 SUT l
and starting a large safety-related motor, the worse case is the dynamic condition (motor starting) and system voltage at minimum.
This condition yields voltages of 97% on the ES MCC's.
1 l
VOLTAGE DROP CALCULATIONS ASSUMPTIONS & METHODS USED IN MAXING CALCULATIONS:
4 LOADS:
G-m,,,L Motor loads were considered " constant kVA Loads" with power factors of 0.9.
Other loads such as heaters, distribution panels, etc., were con-sidered as " Constant Impedance Loads".
Loads taken from Crystal River Unit 3 " Plant Auxiliary Loading Sum-mary" revised February 15, 1977.
This summary was made using name-plate voltages and currents.
Safety-related loads were taken from the Crystal River Unit 3 FSAR i
Table 8-1 and supplemented by the Plant Auxiliary Load Summary as re-quired.
WORST CASE CONDITIONS m
Steady State 1)
System voltage at minimum with all coincidental unit loads, emer-gency block sequences blocks 1 thru 4 including the manually applied loads of FSAR Table 8-1 on the startup transformer.
2)
System voltage at maximum with all coincidental unit loads, and the emergency block loading sequence blocks 1 thru 4 including the manually applied loads of FSAR Table 8-1 on the startup transformer.
3)
System voltage at minimum and maximum with emergency block loads 1 thru 4 on the Unit 1 and 2 startup transformer.
4)
System voltages at minimum and maximum while backfeeding the Unit Aux. Transf. from the Unit Step-up Transformer at minimum plant loading conditions (during refueling).
5)
System voltage at maximum with minimum plant loading (during refueling) on the startup transformer.
Dynamic 1)
System voltages minimum and maximum with all coincidental unit loads, emergency block loading sequence blocks 1 thru 4 including the manually applied loads of FSAR Table 8-1 and starting a large safety-related motor on the startup transformer.
2)
System voltages minimum and maximum with emergency block loads 1 thru 4 and starting a large safety-related motor on the Unit 1 &
2 startup transformer.
L
3)
Systec voltages at minimum and maximum while backfeeding the Unit Auxiliary Transformer from the Unit Step-up Transformer at mini-mum plant loading conditions (during refueling) and starting a large safety-related motor.
4)
System voltages minimum and maximum with all coincidental unit loads, emergency block loading sequence blocks 1 thru 4 including the manually applied loads of FSAR Table 8-1 and starting the largest non-safety related load on the startup transformer.
5)
System voltages minimum and maximum with all coincidental unit loads, emergency block loading sequence blocks 1 thru 4 including the manually applied loads of FSAR Table 8-1 and starting the largest 480V safety-related motor on the startup transformer.
BASE VALUES Power:
100 MVA = 1.0 per unit (p.u.)
Voltage:
4.16 kV = 1.0 p.u.
Current:
13,879 A = 1.0 p.u.
SYSTEM V0LTAGE REQUIREMENTS System voltage to the startup and Unit 1 & 2 startup transformers is 240 kV nominal, however, it is maintained at the Crystal River Unit 3 sit to + 1.5% of the nominal, therefore:
Minimum voltage to MTTR - 2 is 236.4 Maximum voltage to MITR - 2 is 243.6 Startup transformer (MITR-2) tap setting is tap number 4 which is the 22450 setting.
Unit 1 & 2 startup transformer tap setting is tap number 1 which is the 235750 setting.
j System voltage to the Unit Step-up Transformer is a 500 kV nominal with an upper limit of 540 kV and a lower limit of 95% of nominal, l
l therefore, the voltage delivered to the unit auxiliary transformer i
through the unit step-up transformer is:
Minimum voltage to MTTR-1 is 18.912 kV Maximum voltage to MTTR-1 is 21.5 kV Unit auxiliary transformer (MTTR-1) tap setting is tap number 5 which is the 20900 setting.
l
COMPUTATIONAL ETHODS The " Constant kVA" and " Constant Impedance" loads from each of the re-spective distribution busses (i.e., 6.9 kV, 4.16 kV and 480V MCC) were sununed as kVA values.
These values were then changed to a per unit value and subsequently changed to rectangular coordinates.
The re-sults are as shown on the attached charts and 1-line diagram.
NOTE: The results are listed as per unit values of n_ameplate voltages.
CONCLUSIONS Steady-State For minimum and maximum system voltage conditions, the results are as summarized on the attached charts.
The only problem area would be during a minimum plant loading condition with maximum system voltage the voltage at the 4.16 kV ES busses is +12% and +10.5% on the 480V ES busses which is above the NEMA standard.
Dynamic For minimum and maximum system voltage conditions, the results are summarized on the attached charts.
One problem area exists on the 480V busses at minimum plant loading and minimum system voltage while backfeeding the unit auxiliary transformer from the unit step-up transformer and starting a large safety-related motor. The voltage on these busses dips to approximately 89% of the nameplate value.
NOTE:
l The loading on the Unit 1 & 2 startup transformer in terms of load from Units 1 & 2 was taken from FSAR paragraph 8.2.3.1.d page 8-10a.
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UNIT 3 START-UP TRANSFORMER VOLTAGE AT ES BUSSES WHILE STARTING LARGEST NON-SAFETY RELATED MOTOR (TRANSF. TAP SETTING: 224250)
Voltages at Nateplate Values (i.e., 460V, 4000V)
Voltage at Min.
Voltage at Max.
BUS System Cond.
System Cond.
MCC (480V)
ES 3Al ES 3A2 1.02678 1.06226 i
ES 3AB ES 381 1.02783 1.06330 ES 3B2 1
SWGR. (0.48kV) i ES Bus 3A 1.02678 1.06226 ES Bus 3B 1.02783 1.06330 i
ES Bus 3A 1.03376 1.06912 ES Bus 3B i
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1 UNIT 3 START-UP TRANSFORMER VOLTAGE AT ES BUSSES WH' E STARTING LARGEST 480V SAFETY-RELATE 0 MOTOR (ThisSF. TAP SETTING: 224250)
Voltages at Nameplate Values (i.e., 460V, 4000V)
Voltage at Min.
Voltage at Max..
BUS System Cond.
System Cond.
MCC (480V)
ES 3Al ES 3A2 1.02261 1.05809 ES 3AB ES 3B1 1.02470 1.06017 ES 3B2 SWGR. (0.48kV)
ES Bus 3A 1.02261 1.05809 ES Bus 3B 1.02470 1.06017 i
ES Bus 3A 1.03064 1.0660 ES Bus 3B l
TABLE 2
1 UNIT 3 START-UP TRANSFORMER V0LTAGE AT ES BUSSES WHILE STARTING LARGEST NON-SAFETY RELATED MOTOR (TRANSF. TAP SETTING: 230000)
Voltages at Nameplate Values (i.e., 460V, 4000V)
Voltage at Min.
Voltage at Max.
BUS System Cond.
System Cond.
MCC (480V)
ES 3Al ES 3A2 0.99861 1.03304 ES 3AB ES 3B1 0.99965 1.03409 ES 3B2 SWGR. (0.48kV)
ES Bus 3A 0.99861 1.03304 ES Bus 3B 0.99965 1.03409 SWGR. (4.16kV)
ES Bus 3A 1.00568 1.0400 l
ES Bus 3B l
l TABLE 3 l
UNIT 3 START-UP TRANSFORMER VOLTAGE AT ES BUSSES WHILE STARTING LARGEST 480V SAFETY-RELATED MOTOR (TRANSF. TAP SETTING: 230000)
Voltages at Nameplate Values (i.e., 460V, 4000V)
Voltage at Min.
Voltage at Max.
BUS System Cond.
System Cond.
MCC (480V)
ES 3Al l
ES 3A2 0.95896 0.99548 ES 3AB ES 381 0.99548 1.02991 ES 382 SWGR. (0.48kV)
ES Bus 3A 0.95896 0.99548 ES Bus 3B 0.99548 1.02991 SWGR. (4.16kV)
ES Bus 3A 1.00256 1.03688 ES Bus 3B TABLE 4
I VOLTAGES AT ES BUSSES WHEN FED FROM UNIT 1 & 2 STARTUP TRANSFORMER (With Sys. Cond. Min. = 1.0278; Max. = 1.0591 Voltages at Nameplate Values (i.e., 460V, 4000V)
STEADY STATE DYNAMIC Voltage at Min. Voltage at Max. Voltage at Min. Voltage at Max.
BUS System Cond.
System Cond.
System Cond.
System Cond.
i j
MCC (480V)
ES 3Al i
ES 3A2 1.00174 1.03513-0.97043 1.00487 ES 3AB ES 381 1.00487 1.04035 0.97357 1.00696 ES 382 SWGR. (0.48kV)
ES Bus 3A 1.00174 1.03513 0.97043 1.00487 ES Bus 3B 1.00487 1.04035 0.97357 1.00696 4
ES Bus 3A 1.01608 1.0504 0.98592 1.01920 ES Bus 3B TABLE 5 i
VOLTAGES'AT ES BUSSES WHILE BACKFEEDING THE UNIT AUX. TRANSF.
l FROM THE UNIT STEP-UP TRANSF. AT MINIMUM PLANT LOADING CONDITIONS (DURING REFUELING)
Voltages at Nameplate Values (i.e., 460V, 4000V)
STEADY STATE DYNAMIC i
Voltage at Min. Voltage at Max. Voltage at Min. Voltage at Max.
BUS System Cond.
System Cond.
System Cond.
System Cond.
i MCC (480V)
ES 3Al ES 3A2 0.90991 1.04139 0.88591 1.02052 ES 3AB ES 381 0.91617 1.04243 0.88696 1.02157 ES 3B2 SWGR. (0.48kV)
ES Bus 3A 0.90991 1.04139 0.88591 1.02052 ES Bus 3B 0.91617 1.04243 0.88696 1.02157 4
ES Bus 3A 0.92872 1.05875 0.90584 1.03792 i
ES Bus 3B I
TABLE 6 A
I 9
4 '
4
. m
4 i
V0LTAGE AT ES BUSSES WITH MINIMUM PLANT LOADING (DURING REFUELING) e i
AND MAXIMUM SYSTEM CONDITION (Transformer Tap Setting 224250)
Voltages at Nameplate Values (i.e., 460V, 4000V)
BUS Voltage at Bus i
MCC (480V)
ES 3Al ES 3A2 1.1040 ES 3AB ES 3B1 1.1050 ES 382 i
SWGR. (0.48kV)
ES Bus 3A 1.1040 i
ES Bus 3B 1.1050 l
SWGR. (4.16kf)
ES Bus 3A' 1.12008 ES' Bus 3B i
l l
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TABLE 7
i VOLTAGE AT ES BUSSES WITH MINIMUM PLANT LOADING (DURING REFUELING) d l
AND MAXIMUM SYSTEM CONDITION (Transformer Tap Setting 230000)
Voltages at Nameplate Values (i.e., 460V, 4000V) 1 i
BUS Voltage at Bus l
MCC (480V)
ES 3AB ES 381 1.07687 ES 382 SWGR. (0.48kV) i ES Bus 3A 1.07583 ES Bus 3B 1.07687 SWGR. (4.16kV)
ES Bus 3A 1.0920 i
ES Bus 3B l
1 i
l TABLE 8 i
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l l
i f
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VOLTAGE AT ES BUSSES FOR WORST CASE V0LTAGE DROP ON i
STARTUP TRANSFORMER (TAP SETTING: 224250)
Voltages at Nameplate Values (i.e., 460V, 4000V)
STEADY STATE DYNAMIC Voltage at Min. Voltage at Max. Voltage at Min. Voltage at Max.
BUS System Cond.
System Cond.
System Cond.
System Cond.
MCC (480V) i ES 3Al ES 3A2 1.02678 1.06226 1.00487 1.04974 ES 3AB ES 3B1 1.02783 1.06330 1.00591 1.05183 ES 382 SWGR. (0.48kV)
ES Bus 3A 1.02678 1.06226 1.00487 1.04974 ES Bus 3B 1.02783 1.06330 1.00591 1.05183 SWGR. (4.16kV) l ES Bus 3A 1.03376 1.06912 1.01192 1.05768 ES Bus 3B TABLE 9 I
h VOLTAGE AT ES BUSSES FOR WORST CASE VOLTAGE DROP ON STARTUP TRANSFORMER-(TAP SETTING: 230000)
Voltages at Nameplate Values (i.e., 460V, 4000V)
STEADY STATE DYNAMIC Voltage at Min. Voltage at Max. Voltage at Min. Voltage at Max.
BUS System Cond.
System Cond.
System Cond.
System Cond.
MCC (480V)
ES 3Al ES 3A2 0.99757 1.03100 0.97670 1.01113 ES 3AB ES 381 0.99965 1.03304 0.97774 1.01530 ES 3B2 SWGR. (0.48kV) 1 ES Bus 3A 0.99757 1.03100 0.97670 1.01113 l
ES Bus 3B 0.99965 1.03304 0.97774 1.01530 l
ES Bus 3A 1.00568 1.0400 0.98384 1.01816 ES Bus 3B TABLE 10 l
...... -... ~..
VOLTAGE AT ES BUSSES WHEN FED FROM THE UNIT 1 & 2 STA' TUP TRANSFORMER & WHILE STARTING R
TWO LARGE MOTORS ON UNIT 1 Voltages at Nameplate Values (i.e., 460V, 4000V)
Voltage at Min.
Voltage at Max.
BUS System Cond.
System Cond.
MCC (480V)
ES 3Al ES 3A2 0.99965 1.03263 1
ES 3AB ES 381 1.00174 1.03513 ES 3B2 SWGR. (0.48kV)
ES Bus 3A 0.99965 1.03263 ES Bus 3B 1.00174 1.03513 SWGR. (4.16kV)
ES Bus 3A 1.01464 1.04624 ES Bus 3B i
l l
TABLE 11
__._ _.. -, - -,, _,,.., _.. _. ~ -. _,. -..
I ATTACHMENT "A" FSAR PAGE 8-10a The startup transformer for Units 1 and 2 at Crystal River is a three wind-ing transformer with the following rating:
High Side 25/33.3/41.66 0A/FA/F0A055 C.
28/37.3/46.66 0A/FA/F0A065 C.
Low Voltage Side, each 12.5/16/67/28.8 0A/FA/F0A055 C.
14/18.65/23.33 0A/FA/F0A065 C.
Consideration of sufficient transformer capacity is based on the worst pos-sible case.
That being when the startup transformer for Units 1 and 2 is carrying the full auxiliaries of the largest unit (Unit 2) with the second unit being started coincident with connection of the Unit 3 4160 Volt Engineered Safeguards Buses from the transformer B winding (as shown on Figure 8-3) during an emergency condition.
Under these conditions, trans-former loading is as follows:
Unit 1, Bus 1B (reduced during plant startup by 30% from full load conditions) 3.54 MVA Unit 2, Bus 2B (full load condition) 6.65 MVA Unit 3, 4160 V Engineered Safeguards Buses (total MVA as shown in table 8-1 times 2) 7.29 MVA 4
TOTAL 17.48 MVA I
The total value of 17.48 MVA is below the FA rating of the winding at 65 C which verifies sufficient transformer capacity.
i 4
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8-10a Am. 37 (2-4-74)
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