ML14120A041
| ML14120A041 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 02/14/2014 |
| From: | Kolodziej J Exelon Generation Co |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML14120A038 | List: |
| References | |
| RS-14-116 19-AN-28, Rev. 001B | |
| Download: ML14120A041 (17) | |
Text
ATTACHMENT 5 BYRON STATION UNITS 1 AND 2 Docket Nos. 50-454 and 50-455 Facility Operating License Nos. NPF-37 and NPF-66 Calculation 19-AN-28, Revision 001B "Calc. for Second-Level & Third-Level Undervoltage Relays"
CC-AA-309-1001 Revision 8 ATTACHMENT 1 Design Analysis Cover Sheet Design Analysis Last Page No. 6 Attachment A, Appendix D I Page AD3 Analysis No.:' 19-AN-28 Revision: 2 001 B Major El Minor 0
Title:
I Calc. for Second-Level & Third-Level Undervoltage Relays EC/ECR No.: EC 389241 & EC 389242 Revision: 1 004 &002 Station(s):' BYR Component(s):
Unit No.: " 1 &2 1AP05E-462-B141X Discipline: ELDC 1AP06E-462-B142X Descrip. Code/Keyword: '° E15 2AP05E-T-462-B241X Safety/QA Class:" SR 2AP06E-T-462-B242X System Code: AP Structure: '* N/A CONTROLLED DOCUMENT REFERENCES
Document No.: From/To Document No.: From/To See Section 5 of this calculation Is this Design Analysis Safeguards Information? I Yes E] No Z If yes, see SY-AA-101-106 Does this Design Analysis contain Unverified Assumptions? '1 Yes El No [] If yes, ATI/AR#:
This Design Analysis SUPERCEDES: "1 Calculation 19-AN-28, Rev. 001A in its entirety.
Description of Revision (list changed pages when all pages of original analysis were not changed): "
This revision adds a third level of protection to the undervoltage protection scheme via new Low Degraded Voltage Relays (LDVRs), with a lower setpoint than the existing DVRs (Second-Level Undervoltage Protection).
The existing analysis from Revision 001 is not affected; the new third-level undervoltage relays (LDVRs) are added to the analysis. The original body of the calculation is unchanged. As such, only Attachment A and the associated appendices are included as part of this minor revision. This calculation supersedes Calculation 19-AN-28, Rev. 001A in its entirety. Approval from Ed Blondin (SMDE) for a minor revision to 19-AN-28 was given on 11/26/2013.
Preparer: 20 J. Kolodziej /Jt~nu~
Print Name /1 Sian Narml /7 Date Method of Review: 21 Detailed Review [ AlternateuCalculation ttched) El Testing El Reviewer: 22 G. Hinshaw Z 1- -(Lý Print Name Sign Name Date Review Notes: 22 Independent review [ Peer revi El (For ExternalAnatysesOnlty)
External Approver: -4 J. Matthews .Print Name u n NaeDate -- 2,0 Exelon Reviewer: 2C UnP] NaMe PrintName
ý JSign p Name (01eo Dt Date Independent 3 rd Party Review Reqd? Is Yes [] No [D Exelon Approver: Z Ltj_-"/
Print Naife 4N fDate
Page AlA CC-AA-1 03-1003 Revision 9 ATTACHMENT 2 Owner's Acceptance Review Checklist for External Design Analyses Page 1 of 3 Design Analysis No.: 19-AN-28 Rev:001B No Question Instructions and Guidance Yes I No / N/A 1 Do assumptions have All Assumptions should be stated in clear terms with enough [
sufficient documented justification to confirm that the assumption is conservative.
rationale?
For example, 1) the exact value of a particular parameter may not be known or that parameter may be known to vary over the range of conditions covered by the Calculation. It is appropriate to represent or bound the parameter with an assumed value. 2) The predicted performance of a specific piece of equipment in lieu of actual test data. It is appropriate to use the documented opinion/position of a recognized expert on that equipment to represent predicted equipment performance.
Consideration should also be given as to any qualification testing that may be needed to validate the Assumptions. Ask yourself, would you provide more justification if you were performing this analysis? If yes, the rationale is likely incomplete.
Are assumptions Ensure the documentation for source and rationale for the 11 El 2 compatible with the assumption supports the way the plant is currently or will be way the plant is operated post change and they are not in conflict with any operated and with the design parameters. If the Analysis purpose is to establish a licensing basis? new licensing basis, this question can be answered yes, ifthe assumption supports that new basis.
3 Do all unverified If there are unverified assumptions without a tracking 0 El assumptions have a mechanism indicated, then create the tracking item either tracking and closure through an ATI or a work order attached to the implementing mechanism in place? WO. Due dates for these actions need to support verification prior to the analysis becoming operational or the resultant plant change being op authorized.
4 Do the design inputs The origin of the input, or the source should be identified and E] 0 have sufficient be readily retrievable within Exelon's documentation system.
rationale? If not, then the source should be attached to the analysis. Ask yourself, would you provide more justification ifyou were performing this analysis? If yes, the rationale is likely incomplete.
5 Are design inputs The expectation is that an Exelon Engineer should be able to correct and reasonable clearly understand which input parameters are critical to the with critical parameters outcome of the analysis. That is, what is the impact of a identified, if change in the parameter to the results of the analysis? Ifthe appropriate? impact is large, then that parameter is critical.
6 Are design inputs Ensure the documentation for source and rationale for the El E]
compatible with the inputs supports the way the plant is currently or will be way the plant is operated post change and they are not in conflict with any operated and with the design parameters.
licensing basis? I I
Page AIB CC-AA-1 03-1003 Revision 9 ATTACHMENT 2 Owner's Acceptance Review Checklist for External Design Analyses Page 2 of 3 Design Analysis No.: 19-AN-28 Rev:001B No Question Instructions and Guidance Yes / No I N/A 7 Are Engineering See Section 2.13 in CC-AA-309 for the attributes that are 0 11 El Judgments clearly sufficient to justify Engineering Judgment. Ask yourself, documented and would you provide more justification ifyou were performing justified? this analysis? If yes, the rationale is likely incomplete.
8 Are Engineering Ensure the justification for the engineering judgment 19 El Judgments compatible supports the way the plant is currently or will be operated with the way the plant is post change and is not in conflict with any design operated and with the parameters. If the Analysis purpose is to establish a new licensing basis? licensing basis, then this question can be answered yes, if the judgment supports that new basis.
9 Do the results and Why was the analysis being performed? Does the stated Ej [I conclusions satisfy the purpose match the expectation from Exelon on the proposed purpose and objective of application of the results? If yes, then the analysis meets the Design Analysis? the needs of the contract.
10 Are the results and Make sure that the results support the UFSAR defined conclusions compatible system design and operating conditions, or they support a with the way the plant is proposed change to those conditions. Ifthe analysis operated and with the supports a change, are all of the other changing documents licensing basis? included on the cover sheet as impacted documents?
11 Have any limitations on Does the analysis support a temporary condition or the use of the results procedure change? Make sure that any other documents been identified and needing to be updated are included and clearly delineated in transmitted to the the design analysis. Make sure that the cover sheet appropriate includes the other documents where the results of this organizations? analysis provide the input.
12 Have margin impacts Make sure that the impacts to margin are clearly shown El [] 5a been identified and within the body of the analysis. If the analysis results in documented reduced margins ensure that this has been appropriately appropriately for any dispositioned in the EC being used to issue the analysis.
negative impacts (Reference ER-AA-2007)?
13 Does the Design Are there sufficient documents included to support the Analysis include the sources of input, and other reference material that is not applicable design basis readily retrievable in Exelon controlled Documents?
documentation?
14 Have all affected design Determine ifsufficient searches have been performed to E [
E]
analyses been identify any related analyses that need to be revised along documented on the with the base analysis. It may be necessary to perform Affected Documents List some basic searches to validate this.
(ADL) for the associated Configuration Change?
15 Do the sources of inputs Compare any referenced codes and standards to the current K and analysis design basis and ensure that any differences are reconciled.
methodology used meet Ifthe input sources or analysis methodology are based on committed technical and an out-of-date methodology or code, additional reconciliation regulatory may be required ifthe site has since committed to a more requirements? recent code
Page AIC CC-AA-1 03-1003 Revision 9 ATTACHMENT 2 Owner's Acceptance Review Checklist for External Design Analyses Page 3 of 3 Design Analysis No.: 19-AN-28 Rev:001 B No Question Instructions and Guidance Yes / No / N/A 16 Have vendor supporting Based on the risk assessment performed during the pre-job K El technical documents brief for the analysis (per HU-AA-1212), ensure that and references sufficient reviews of any supporting documents not provided (including GE DRFs) with the final analysis are performed.
been reviewed when
_ necessary?
17 Do operational limits Ensure the Tech Specs, Operating Procedures, etc. contain support assumptions operational limits that support the analysis assumptions and Sand inputs? inputs.
Create an SFMS entry as required by CC-AA-4008. SFMS Number: -- *f. !
CALCULATION TABLE OF CONTENTS 19-AN-28 Rev. 001 B Page A2 of A13 SECTION: PAGE NO. SUB-PAGE NO.
TITLE PAGE Al OWNER'S ACCEPTANCE REVIEW AIA-AIC TABLE OF CONTENTS A2 1.0 PURPOSE A3 2.0 METHODOLOGY A3 3.0 ACCEPTANCE CRITERIA A4 4.0 ASSUMPTIONS AND LIMITATIONS A5 5.0 DESIGN INPUT A5
6.0 REFERENCES
A6 7.0 IDENTIFICATION OF COMPUTER PROGRAMS A8 8.0 CALCULATIONS A8
9.0 CONCLUSION
S AND RECOMMENDATIONS A12 10.0 APPENDICES A13 A) ELMS-AC Plus Load Flow Reports AA1 - AA129 B) Calculation Input ABI - AB33 C) ELMS-AC Station File Changes ACI - AC262 D) High Impedance Fault Clearing Time ADI - AD3 i i
CALCULATION PAGE ICALCULATION NO. 19-AN-28 REVISION NO. 001BB Attachment A PAGE NO. A3 of A13 1.0 PURPOSE The normal (non-accident) time delay associated with the 4.16 kV ESF bus degraded voltage relays (DVRs) could allow the voltage at the 4.16 kV level to remain at extremely low levels for an extended period as long as 5 minutes and 40 seconds (Section 3.3.5.2 of Ref 6.16). To ensure that the safety-related motors will be available and undamaged during a degraded grid voltage condition, new definite-time third-level undervoltage relays (i.e., low degraded voltage relays (LDVRs)) are being installed.
This revision establishes a voltage setpoint for the new LDVRs that is below the existing second-level undervoltage relays (i.e., DVRs) and above the first-level undervoltage relays (i.e., loss of voltage relays (LVRs)) on the 4.16 kV ESF Buses 141, 142, 241, and 242.
The accuracy of the relay, the relay setting tolerance and the accuracy of any associated components are considered when establishing the setpoint for the newly installed relay.
Analytical limits are developed in this calculation for the voltage and time delay settings. The settings developed in this calculation will be evaluated against existing limits defined in the Technical Specifications.
2.0 METHODOLOGY The new LDVRs ( 3 rd level) are harmonically filtered ABB 27N undervoltage relays, same as the existing DVRs (2 "dlevel) and mounted in the same location (Aux. PT & Relay Compartment of the associated switchgear), and therefore have the same tolerances calculated in the base revision of this calculation used to determine the relay setpoint.
The 4.16 kV Switchgear loads are analyzed in Calculations 19-AN-3 & 19-AN-7 (Units I & 2 respectively), and the 480V Switchgear loads are analyzed in Calculations 19-AU-4 & 19-AU-5 (Units I & 2 respectively). An individual analysis of the overcurrent protection for each low voltage safety-related load, under normal operating conditions at a reduced bus voltage is included in References 6.11
& 6.12.
2.1 Minimum Allowable Value The setpoint for the new LDVRs must be high enough to prevent the stalling and tripping of loads (due to actuation of overcurrent protection devices).
2.1.1 The most limiting ESF motor ratio of breakdown torque to running torque will be determined.
2.1.2 Using Equation 2.1.2, the breakdown torque will be determined for lowered system voltages.
%TED Vmd =
( Vreduced 2 2 X %TBD,, V,,a Equation 2.1.2
, Vrated )
2.1.3 The lowest voltage at the ESF 4.16 kV Switchgear buses that supports an acceptable breakdown torque will be determined by iteration using ELMS-AC PLUS.
2.1.4 In order to preclude ESF motor stalling, the worst case (highest) of the voltages determined using the methodology from Section 2.1.3 is used as the minimum allowable value (analytical limit) when determining the new LDVR setpoint. This calculation will
CALCULATION PAGE CALCULATION NO. 19-AN-28 REVISION NO. 001B Attachment A PAGE NO. A4 of A13 use Conditions 2 and 3 in the station ELMS-AC load-flow models (References 6.8 &
6.9) to represent maximum summer and winter loading under normal operating conditions, respectively. Since SX flows and Chiller loads are higher in the summer months, the summer non-LOCA model (ELMS-AC Condition 2) will be used. The ELMS-AC model will be revised to model the applicable ESF loads that are normally running, as identified in Reference 6.10 (shown in Appendix C).
2.2 Maximum Allowable Value The function of the LDVR is to ensure that equipment is not damaged by prolonged exposure to extremely low voltages. The maximum allowable voltage is such that the LDVRs do not operate if the ESF motors block start following an SI signal; this scenario is evaluated in References 6.11
& 6.12. The setpoint will be chosen based on the value determined using the methodology of Section VIII of the base calculation.
2.3 Time Delay Setting Section 8.3 of the Byron UFSAR states that the 4160 V ESF Switchgear are protected from faults via relays (Westinghouse CO series overcurrent relays, Table 8.3-6) to disconnect faults with minimum system disturbance. Thus, the initial time delay associated with the LDVRs should allow the overcurrent relays to clear faults prior to tripping the bus. Appendix D of this calculation determines the maximum fault clearing time for a 4.16 kV circuit breaker based on a high impedance fault on a 480 V bus fed from a protected 4.16 kV ESF bus. Appendix D is used as a starting point to determine the initial setpoint which ultimately must be long enough to prevent spurious trips from system transients and short enough to prevent equipment damage. The LDVR time delay setpoint is based on engineering judgment. The methodology used in Appendix D is as follows:
2.3.1 Using the ELMS-AC models, the division with the highest impedance was selected to determine the longest fault clearing time.
2.3.2 The three phase, bolted fault current is calculated from the system impedance, converted to a phase-to-phase fault, and reduced to account for an arcing fault via References 6.26
& 6.27.
2.3.3 The phase-to-phase fault current on the 4.16 kV bus is compared to the trip curve for the CO-9 overcurrent relay to determine the fault clearing time (Reference 6.4).
3.0 ACCEPTANCE CRITERIA 3.1 Low Degraded Voltage Relay Consistent with industry practice, the ultimate tripping point of the LDVR setpoint should be low enough to prevent spurious actuation during transients such as those experienced during the starting of large plant motors. The setpoint must be high enough to prevent the stalling, tripping (due to overcurrent protection devices) or damaging of Class IE motors due to low voltage. The time delay setpoint should allow the overcurrent protective devices to clear faults prior to tripping the bus on low degraded voltage.
CALCULATION PAGE I CALCULATION NO. 19-AN-28 REVISION NO. 001B Attachment A PAGE NO. A5 of A13 4.0 ASSUMPTIONS AND LIMITATIONS 4.1 Assumptions Requiring Verification None.
4.2 Assumptions NOT Requiring Verification 4.2.1 It is assumed that onsite events, such as large motor starts, will cause larger transients in onsite system voltages than events elsewhere in the offsite electrical system. The strength and stability of the offsite electrical system is routinely evaluated considering various transients to ensure its adequacy to support the onsite distribution system.
4.2.2 At the 480 V level the breakdown torque of each of the Class IE motors, with the exception of the Control Room HVAC Return Fans (See Section 5.1.4.2), is assumed to be 200% of the rated running torque. This is the minimum required by NEMA Standard MG 1-2011 (Reference 6.2) for Design A and B motors <200hp. This is acceptable for Byron Station since the safety-related motors at the 480 V level are less than 200hp.
5.0 DESIGN INPUT 5.1 Monitoring Circuit Elements 5.1.1 Loss of Voltage Relays (Reference 6.22)
Type Westinghouse Model CV-7 Voltage Tap Settings (Vac) 55, 64, 70, 82, 93, 105, 120, 140 Time Lever Settings 1/2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 The LVRs are currently set to time lever setting 2 which corresponds to 1.8 seconds with a 10% setting tolerance (References 6.5 & 6.22).
5.1.2 Potential Transformers (Reference 6.3)
Type Westinghouse Model 9146D46G02 Voltage Ratio 4200 - 120V Accuracy Class 0.3W, X, Y and 1.2 Z The PT error and PT ratio used in the calculations in Section 8 are derived from the input data as follows: 0.3 PT _error = 1 Accuracy_ Class = I --- = 0.997 100 100 PT ratio =1
_ 4200 = 35
- 120
CALCULATION PAGE I CALCULATION NO. 19-AN-28 REVISION NO. 001B Attachment A PAGE NO. A6 of A13 5.1.3 4 kV ESF Motor Breakdown Torques Motor Rated Running Rated Full Breakdown BDT/ Reference #
Voltage Load % Load Torque Torque FLT (V) (Worst Case) (FLT) LB-ft (BDT) LB-ft Aux. Bldg. Vent Sys. Exh Fans 4000 98.8% 2209 5478 248% 6.4, 6.8, & 6.9 Component Cooling Pumps 4000 96.7% - - 238% 6.4, 6.8, & 6.9 Centrifugal Charging Pumps 4000 115% - - 270% 6.4, 6.8, & 6.9 Aux. Bldg. Vent Sys. Sup. Fans 4000 108.3% 1030 2750 267% 6.4, 6.8, & 6.9 Containment Spray Pumps 4000 0% 1760 4360 248% 6.14. 6.8, & 6.9 Aux. FW Pumps 4000 0% 1840 4960 270% 6.13, 6.8, & 6.9 RHR Pumps 4000 0% 1075 3000 279% 6.4, 6.8, & 6.9 SI Pumps 4000 0% - - 262% 6.4, 6.8, & 6.9 ESW Pumps 4000 109.6% 7407 - 250% 6.15, 6.8, & 6.9 Control Room Chillers 4000 73.8% 473 1155 244% 6.4, 6.8, & 6.9 5.1.4 460 V ESF Motor Breakdown Torques 5.1.4.1 The 460 V ESF motors breakdown torque to rated torque ratio is 200% and is addressed in Assumption 4.2.2.
5.1.4.2 The 460 V Control Room HVAC Return Fans (OVC02CA & OVC02CB) run at 49HP and are rated 40HP (Reference 6.8). The fans have a breakdown torque of 225% of motor rated torque (Reference 6.23).
5.1.5 ABB ITE-27N Undervoltage Relay The total negative error (TNE) is 1.42%, the total positive error (TPE) is 0.90%, a pickup/dropout ratio of 0.5%, and harmonic filter 41 IT6375-L-HF-DP (Reference 6.21 Pages 5 & 16). The relay has an adjustable time delay from 0.1-I seconds (Reference 6.6 Page 4). The time delay error is equal to the greater of +/- 10% or +/- 20 milliseconds.
(Reference 6.6 Page 5) 5.1.6 NTS Series 812 Timing Relays The relays are accurate to 2% of the setpoint over the entire operating range. The 812 6-02-0 relay has an operating range of 0.5 - 5 seconds (Reference 6.25).
6.0 REFERENCES
6.1 NUREG-0800, Standard Review Plan, Chapter 8, Branch Technical Position PSB- 1, Rev. 0, July 1981.
6.2 NEMA MG 1-2011, Part 12 (Appendix B Page AB2).
CALCULATION PAGE CALCULATION NO. 19-AN-28 REVISION NO. 001B Attachment A PAGE NO. A7 of A13 6.3 S&L DIT No. BB-EPED-0178, dated 5-7-1992, Undervoltage Relay Accuracy Calculation Input Data (Appendix B Page AB3).
6.4 Calculation 19-AN-3, Rev. 16, Protective Relay Settings for 4.16kV ESF Switchgear (Appendix B Pages AB4 - AB 10).
6.5 Work Order 00492205, 03/31/04 Bus 242 Tech Spec Undervoltage Relays (Appendix B Page AB 11).
6.6 ABB lB 7.4.1.7-7 Issue E, Instructions Single Phase Voltage Relays.
6.7 Exelon TODI BYR- 12-002, Rev. 000, ELMS File Revision Information.
6.8 ELMS-AC PLUS modification files for Byron - Unit 1; B IA4141.M97 and B IA4142.M97 (Appendix B Pages ABI2 & ABI3).
6.9 ELMS-AC PLUS modification files for Byron - Unit 2; B2A4241.M75 and B2A4242.M75.
6.10 EC 377631 Rev. 000, Evaluation And Technical Basis For The AP System Second Level Undervoltage (Degraded Voltage) Time Delay Setting, Approved Feb. 3, 2010 (Appendix B Page AB14).
6.11 EC 389241 Rev. 004, Degraded Voltage 5 Minute Timer Resolution - Unit I (Appendix B Page ABI5).
6.12 EC 389242 Rev. 002, Degraded Voltage 5 Minute Timer Resolution - Unit 2 (Appendix B Page ABI6).
6.13 Vendor Drawing 664834, Westinghouse Thermal Limit and Acceleration Time vs. Current Curve (Appendix B Page AB 17).
6.14 Vendor Drawing 664832, Westinghouse Thermal Limit and Acceleration Time vs. Current Curve (Appendix B Page AB 18).
6.15 Vendor Drawing DHC770322-I, ESW Pump Motors (Appendix B Page AB 19).
6.16 Technical Specification 3.3.5, Loss of Power (LOP) Diesel Generator (DG) Start Instrumentation.
6.17 Station Drawing 6E-1-4030AP30, Rev. U, Schematic Diagram 4160V ESF SWGR Bus 141 Undervoltage Relays: PR9A-427-B 14 1, PR9C-427-B 141, PR29A-427-ST 11, & PR29C-427-ST 11.
6.18 Station Drawing 6E-1-4030AP39, Rev. U, Schematic Diagram 4160V ESF SWGR Bus 141 Undervoltage Relays: PRIOA-427-B 142, PR1OC-427-B 142, PR32A-427-ST12, & PR32C-427-ST12 6.19 Station Drawing 6E-2-4030AP30, Rev. T, Schematic Diagram 4160V ESF SWGR Bus 241 Undervoltage Relays: PR31A-427-B241, PR31C-427-B24 I, PR29A-427-ST21, & PR29C-427-ST2 1.
6.20 Station Drawing 6E-2-4030AP39, Rev. Q, Schematic Diagram 4160V ESF SWGR Bus 242 Undervoltage Relays PR29A- 427-B242, PR29C-427-B242, PR5A- 427-ST22, & PR5C-427-ST22.
6.21 Calculation 19-AN-28, Rev. 001, Calc. For Second-level Undervoltage Relay Setpoint (Appendix B Pages AB20 & AB2 1).
CALCULATION PAGE CALCULATION NO. 19-AN-28 REVISION NO. OOR1B Attachment A PAGE NO. A8 of A13 6.22 Westinghouse I.L. 41-201Q, Type CV Voltage Relay, December 1988(Appendix B Page AB22).
6.23 Reliance A-C Motor Performance Data No. EO1 I 1A-B-007, June 1977 (Appendix B Page AB23).
6.24 Exelon Procedure MA-MW-772-702 Rev. 0, Calibration of Voltage Protective Relays (Appendix B Page AB24).
6.25 NTS Manual No. 812-01, NTS Series 812 Timing Relay, March 1999 (Appendix B Pages AB25 -
AB26).
6.26 IEEE Std 141-1993, IEEE Recommended Practice for Electric Power Distribution for Industrial Plants (Appendix B Page AB27).
6.27 IEEE Std 242-2001, IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems (Appendix B Page AB28).
6.28 IEEE Std C37.91-2008, IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems (Appendix B Page AB29).
6.29 Calculation 19-AN-7, Rev. 11,Protective Relay Settings for 4.16kV ESF Switchgear (Appendix B Page AB30).
6.30 Fitzgerald, A. E., Kingsley Jr., Charles, and Umans, Stephen D. Electric Machinery. Sixth Edition.
New York: McGraw-Hill, 2003 (Appendix B Page AB31 - AB33).
6.31 Calculation 19-AN-3, Rev. 16D, Protective Relay Settings for 4.16kV ESF Switchgear 7.0 IDENTIFICATION OF COMPUTER PROGRAMS 7.1 Microsoft Word 2003 (Text only), S&L Computer No. ZD6585, Program No. 03.1.286-1.0.
7.2 Advanced AC Electrical Load Monitoring System (ELMS-AC PLUS) Ver 1.2, S&L Computer No. 8809, Program No. 03.7.379-1.2.
7.3 Mathcad Version 14.35, S&L Computer No. ZL8156, Program No. 03.7.548-1435.
8.0 CALCULATIONS 8.1 The minimum allowable voltage for the new LDVR actuation has been selected as follows:
8.1.1 Selection of Limiting Breakdown Torque 8.1.1.1 Motors running at reduced voltages have reduced torque output proportional to the square of the voltage ratio. Therefore, Equation 2.1.2 is used to determine the breakdown torque at reduced voltage.
%TBD@Vreduced =rate 2°/TBD@Vw V. ,.atd )
The minimum allowable voltage to preclude motor stall at the 4.16kV level has been determined as follows:
CALCULATION PAGE CALCULATION NO. 19-AN-28 REVISION NO. 001B Attachment A PAGE NO. A9 of A13 Vminallowed = 4000V %TBD@Vited , where Vmin.allowed = Vred.ced (See Section 5.1.3)
Induction motors are typically utilized in constant-speed applications, and because Pmotor = Tmotor 01, the motor BHP is proportional to the motor torque (Ref. 6.30). Therefore, for motors running above rated power, the BHP (from References 6.8 and 6.9) as a percent of motor rated power is used for TBD@Vreduced.
Motor TBD Vrated TBD@ Vreduced
- Vmin allowed
(%) (%) (V)
Aux. Bldg. Vent Sys. Exh Fans 248 100 2540.0 Component Cooling Pumps 238 100 2592.8 Centrifugal Charging Pumps 270 115 2610.5 Aux. Bldg. Vent Sys. Sup. Fans 267 108.3 2547.5 Containment Spray Pumps 248 100 2540.0 Aux. FW Pumps 270 100 2434.3 RHR Pumps 279 100 2394.7 SI Pumps 262 100 2471.2 ESW Pumps 250 109.6 2648.5 Control Room Chillers 244 100 2560.7
- TBDvw,ýd is proportional to the motor BHP from References 6.8 & 6.9, for motors running below rated HP 100% torque is used for conservatism.
At a reduced voltage of 2648.5V (66.2% of 4000V), the breakdown torque will equal the running torque for the Essential Service Water Pump. This bounds the 4 kV motors.
8.1.1.2 Per Assumption 4.2.2, the minimum breakdown torque for the Class IE motors at the 480 V level is 200%.
8.1.1.3 The only 480 V level loads running above rated load are the Control Room HVAC Return Fans, which are rated 40HP and run at 49HP or 122.5%
(References 6.8 & 6.9).
8.1.1.4 Motors running at reduced voltages have reduced torque output proportional to the square of the voltage ratio. Therefore, Equation 2.1.2 is used to determine the breakdown torque at reduced voltage of low voltage motors running at full load.
2
= Vreduced
%TaoD = I %TBD @,V.,
CALCULATION PAGE ECALCULATION NO. 19-AN-28 REVISION NO. 001B Attachment A PAGE NO. Al0 of A13
( VMinAllow460V *2
/TBD Q V,..d = 100== 460V x 200 (Section 5.1.4)
='VMinAllow60v = 325.3V 8.1.1.5 Equation 2.1.2 is used to determine the breakdown torque at reduced voltage for the Control Room HVAC Return Fans:
%TsD@v,*,d,* = 122.5 VinAlow460V Jx 225 (Section 5.1.4.2)
SVinAiiow46V = 339.42V At a reduced voltage of 339.42V (73.79% of 460V), the breakdown torque will equal the running torque for the Control Room HVAC Return Fan. Because this is higher than the limiting voltage for the 4.16kV ESF buses calculated in Section 8.1.1.1, this is the limiting voltage. Therefore, the station ELMS model has been analyzed to determine the 4.16kV ESF bus voltage required to ensure all 480V Control Room HVAC Return Fans are > 73.79% of rated terminal voltage, while all other 480V ESF motors are > 70.72% (325.3Vtemnai /
460V.) of rated terminal voltage. From Appendix A page AA 1 the minimum required voltage on each of the four buses, 141, 142, 241 & 242, are 3056.4V, 3075.OV, 2914.3V and 2955.2V respectively; therefore highest minimum voltage required on all four buses (141, 142, 241 & 242) is determined to be 3075.OV (3075.OV/35 = 87.86V, Section 5.1.2) and is used as the Analytical Limit (AL).
8.1.1.6 Voltage Setpoint 4160 V Switchgear buses 141 (Div. 11), 142 (Div. 12), 241 (Div. 21), and 242 (Div. 22).
Nominal Relay Dropout Setpoint = Minimum Relay Dropout + Total Negative Error (in percent of nominal relay dropout setpoint, from Section IX.D of the base revision)
= 87.86V/(1-0.0142)
= 89.13V This equates to 89.13V*35 (PT Ratio) = 3119.55V.
EC 377631 (Ref. 6.10) determined that no damage will result to permanently connected Class I E loads as a result of operation at degraded voltage conditions for the maximum allowable duration of the transients as specified in the Technical Specifications (340 seconds) at a 4.16 kV Switchgear bus voltage of 3120V (75%). Therefore the new LDVR setpoint is 3120V/35 = 89.143V rounded up to the nearest hundredth volt yields 89.15V.
8.1.1.7 Time Delay Setting The LDVR time delay setting needs to be long enough to prevent spurious tripping, and short enough to protect the motors from overload tripping and
CALCULATION PAGE CALCULATION NO. 19-AN-28 REVISION NO. 001 B Attachment A PAGE NO. All of Al3 lockout due to prolonged exposure to low bus voltage (low degraded voltage).
The LDVR should trip before overload relays for a sustained low bus voltage condition.
Minimum Setting Criteria Section 8.3 of the Byron UFSAR states that the 4160 V ESF Switchgear are protected from faults via relays (Westinghouse CO series overcurrent relays, Table 8.3-6) to disconnect faults with minimum system disturbance. Thus, the initial time delay associated with the LDVRs should allow the overcurrent relays to clear faults prior to tripping the bus. Attachment D of this calculation determines the maximum fault clearing time for a 4.16 kV circuit breaker based on a high impedance fault on a 480V bus fed from a protected 4.16 kV ESF bus. The longest fault clearing time has been determined to be approximately 2 seconds, with additional margin of 1 second to establish the nominal setpoint (3 seconds) and allow time for the bus voltage to recover. The contacts of the new LDVR that are part of the trip circuit are connected in series with a new NTS time delay relay connected to prevent spurious 4.16 kV bus trips when repowering a dead bus (References 6.11 & 6.12).
The total time delay setpoint for the LDVR and NTS time delay relay is 3 seconds. The LDVRs will have a time delay of 0.5 second and the NTS time delay relays will have a time delay of 2.5 seconds.
The time delay tolerance is taken from Sections 5.1.5 and 5.1.6 and the total time delay error is calculated below:
TPE = TNE = (LDVR time delay
- tolerance) + (NTS time delay
- tolerance)
= 0.5s
- 10% + 2.5s
- 2% = 0.1s Maximum Setting Criteria The 4kV and 480V ESF motors are protected from damage, due to overcurrent, by thermal overload (TOL) relays and phase overcurrent relays. The maximum LDVR time delay is evaluated below to ensure coordination with the motor overcurrent protection.
The WO MCR chillers are the only normally running 4.16 kV loads running on Buses 141, 142, 241, and 242 that lockout following a trip. The 480V MCC motor loads have thermal overload relays that lockout following a trip. The remaining 4.16 kV loads and 480V switchgear loads will restart if tripped on overcurrent prior to the LDVRs disconnecting the associated bus (References 6.11 and 6.12).
Calculation 19-AN-3, Rev. 16D (Ref. 6.31) established that the WO MCR Chiller motor overcurrent relay would not trip for the LDVR setpoint plus total negative error, which equates to 1/(73.9%) = 135.32%. For a sustained undervoltage at the Loss of Voltage Relay allowable value of 65.6% (Section 3.3.5.2 of Ref. 6.16), full load current for the motors would be 1/(65.6%) =
152.4%. Even at a full load current of 250%, the WO MCR chiller motor CO-5 relay would trip in approximately 5 seconds. The TOL trip curves for the 480V
CALCULATION PAGE I CALCULATION NO. 19-AN-28 REVISION NO. O01B Attachment A PAGE NO. A12 of A13 MCC loads show a cold start minimum trip time of approximately 25 seconds for 250% of the trip rating. Therefore, the LDVR setting should not be any higher than 5 seconds.
LDVR Time Delay Setting In order to have margin between the maximum allowable value and the setpoint for the time delay, the maximum allowable value is set at 3.5 seconds. The maximum allowable value of 3.5 seconds is greater than the nominal setpoint (3 seconds) plus the total positive error (0.1 seconds). The LDVR setting of 3.5 seconds is acceptable because it is above the minimum setting and below the maximum setting, with margin for timing tolerances.
8.1.2 Maximum Relay Reset The maximum reset voltage is calculated from the maximum dropout voltage and PU/DO ratio as shown in Section 5.1.5:
Max. Relay Dropout = Nominal Relay Dropout (DO) + TPE (in % of DO)
= 89.15V * (1.0 + 0.009)
= 89.95V Max. Relay Pickup = Max. Relay Dropout / PU/DO ratio
= 89.95V / 0.995 = 90.40V Max. Reset Bus Voltage = 90.40V
- 35 = 3164V 8.2 Results With the new LDVR set at 89.15V, the LDVRs will actuate prior to any safety-related motors stalling and thus satisfying the acceptance criteria. The motor protection is analyzed with the LDVRs set at 89.15V and 3 seconds in ECs 389241 & 389242 (References 6.11 & 6.12) and determined that the motor protection, for loads that will lockout following a trip, will not trip on the normally running, safety-related motors during a degraded voltage condition prior to the DVR 5 minute timer transferring the SR loads to the emergency diesel generators.
9.0 CONCLUSION
S AND RECOMMENDATIONS 9.1 Low Degraded Voltage Relay Settings Based on the acceptance criteria of Section 3.0 and the calculations of Section 8.0, the following relay settings are recommended:
Nom. Relay Dropout Setpoint = 89.15V [3120.25V (primary side voltage)]
Nom. Relay Pickup (Reset) Setpoint = 89.15V/ 0.995 = 89.60V Maximum Relay Reset = 90.40V Time Delay Setpoint = 0.5 seconds
CALCULATION PAGE CALCULATION NO. 19-AN-28 REVISION NO. 001B Attachment A PAGE NO. A13 of A131 9.2 Time Delay Relay Setting Based on the acceptance criteria of Section 3.0 and the calculations of Section 8.0, the following relay setting is recommended:
Time Delay Setpoint = 2.5 seconds 10.0 APPENDICES A) ELMS-AC Plus Load Flow Reports B) Calculation Input C) ELMS-AC Station File Changes D) High Impedance Fault Clearing Time