ML13330B356

Charging Pump Motor Overload Evaluation

ML13330B356
Person / Time
Site:	San Onofre
Issue date:	07/31/1988
From:	Westinghouse, Div of CBS Corp
To:	NRC Office of Administration & Resources Management (ARM)
Shared Package
ML13330B355	List: ML13330B354 ML13330B356
References
TAC 68439 88-13, NUDOCS 8807250284
Download: ML13330B356 (10)

Text

I ENGINEERING REPORT 8U3 SOUTHERN CALIFORNIA EDISON COMPANY San Onofre Nuclear Generating Station, Unit 1 Charging Pump Motor Overload Evaluation Performed by Westinghouse Electric Corporation Heavy Industry Motor Support Center Round Rock, Texas July 1988 8807250284 PDR ADOCK 05000206 P

PDC

Conclusion of Evaluation Charging pump motors MG8A and MG8B (Westinghouse S.0. 65F15619) at San Onofre Nuclear Generating Station, Unit 1, were evaluated to determine if they would operate satisfactorily during accident conditions.

The conditions initially specified were as follows:

Motor load 136% of rated for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> with 104*F ambient followed by Motor load 125% of rated for 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> with 104*F ambient followed by Motor load 100% of rated indefinitely with 80*F ambient.

Calculations show that the motor could carry the mechanical overload without intruding on the design factors of safety. Temperature calcu lations show that the motor can also carry the thermal overload without exceeding the normal class B temperature rise of the insulation system.

Bearing temperatures were checked and found to be well within design limits.

The machine will perform satisfactorily under accident con ditions.

The conditions were later altered to carry 136% load for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> instead of 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and ambient was changed to 80*F instead of 104*F. The results for both sets of conditions are included in the report.

2

Identification of Pump Motor Evaluated South California Edison Designation Charging Pump Motors MG8A and MG8B Shop Order Number 65F15619 W Outline Drawing Number 4117D64 Motor Rating 600HP, 4160 Volt, 2 Pole, 60 Hz, 1.15 S.F.

Purpose of Motor Study To determine if motor would operate satisfactorily under temporary overload and higher than normal ambient conditions present during an accident.

The temporary conditions were defined as:

1362 load for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> with 104*F ambient and 100% relative humidity followed by 1252 load for 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> with 104*F ambient and 100%

relative humidity.

References

1. Southern California Edison letter of June 27, 1988 from G.

Stawniczy to B. Craig.

2. Southern California Edison letter of June 29, 1988 from A.J.

Thiel to B. Craig.

3. Southern California Edison letter of July 1. 1988 from G.

Stawniczy to L. Elder.

3

WESTINGHOUSE ELECTRIC CORPORATION HEAVY INDUSTRY MOTOR SUPPORT CENTER ROUND ROCK, TEXAS HIMSC ENGINEERING REPORT ER 88-13 DATE:

July 14, 1988

SUBJECT:

Study to evaluate effect of overload operation during accident conditions on motor S.O. 65F15619.

ABSTRACT:

Motors were evaluated mechanically and thermally to determine whether operation would be satisfactory under overload seen during accident conditions.

Overload conditions were initially defined as 136% load for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at 104*F ambient followed by 125% load for 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> at same ambient.

Conditions were later altered to change the 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and the ambient to 80*F for both loads.

Shaft stresses, insulation temperatures, and bearing temperature were checked for both sets of conditions.

Motor will stay within standard design stresses and temperatures under both sets of conditions and will provide reliable operation.

By: _

APPROVED':

D. McEachron

MANAGER, BIMSC

MANAGER, ENGINEERING JH01:pj6:7

Discussion:

The motors built on *Shop Order 65F15619 vere investigated to determine if they would operate reliably under accident conditions specified by Southern California Edison in letters dated June 27, 1988; June 29, 1988; and July 1, 1988. Attachments 1,2, and 3.

There were three conditions specified as follows:

1. 1362 of rated load for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> with 104*F ambient and 100%

relative humidity.

2. Item 1. followed by 125% of rated load for 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> with 104*F ambient and 100% relative humidity.

3. Item 2. followed by 100% of rated load for an indefinite period with 80*F ambient and 100% relative humidity.

The limitations examined in the motor are in 3 areas:

1. Mechanical stress in the motor shaft.

2.

Thermal limitations of the motor insulation system.

3.

Bearing temperature limitations.

The resources used in this study were standard iestinghouse stress calculation procedures, the *shop test report on this Shop Order, and electrical design program *HE 7337 revision 11/20/83.

• Westinghouse Proprietary 5

Mechanical Stresses.

The highest stress areas are the rear journal and the coupling exten sion. The shaft material has a yield strength of 37,000 psi and the key material 51,000 psi. The yield point of the key in shear is 27,000 psi.

The journal diameter is 2.750 inches; shaft extension diameter is 2.875 inches (2.708 inches equivalent diameter with 5/8 inch by inch key).

Using Webtinghouse standard safety factors in the stress calculations shows the journal to be capable of transmitting 925 horsepower and the shaft extension to be capable of transmitting 885 horsepower; both of which are above the 136% load or 816 horsepower requirement. The key and keyway were also checked. The key in the shear mode will transmit 1290 horsepower and in key bearing stress mode will transmit 1060 horsepower. From a mechanical stress viewpoint the motor will carry 816 horsepower with no distress.

Insulation System.

The motor was purchased as a 60*C rise machine but was manufactured with a class B insulation system which is rated for a 90*C rise over 40*C ambient on a 1.15 service factor machine. This system would have an expected life of 20 years if operated continuously at the 130*C total temperature allowed by the class B rating.

TM Westinghouse Thermalastic insulation is a sealed system and is not affected by humidity so long as the space heaters are turned on when the motor is idle. When the motor is running there is sufficient internal heating in the motor to prevent any condensation or other ill effects from high humidity.

This motor was factory tested at 50% load. The electrical design program was used to calculate expected temperature rise at 50%, 100%,

125%, and 136% of rated load. The ratio of actual temperature rise to calculated temperature rise at 502 load was used as a multiplier to correct the calculated temperature rise at the other load points to give the actual expected temperature rise. The temperature on this machine would be stable after 3 to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> operation so the expected tempera tures given are steady state values.

LOAD (%)

Expected Temp.

Ambient (*C)

Total Temperature (*C)

Rise C) 136 79 40 119 136 79 27 106 125 70 40 113 125 70 27 97 100 51 27 97 6

All of the load points result in a total temperature less than that allowed for standard operating conditions by the insulation system. The motor insulation will handle the accident conditions with no ill-effects.

Bearings.

The total bearing temperature allowable on these units is 90*C. The total temperature during the 50% load factory test was 36.C on the front bearing and 35'C on the rear bearing with a 29*C ambient. The actual bearing temperature rise of 5-6*C could be expected to increase to not more than 15*C when motor load is increased to 816 HP. The total temperature would then be 15 + 40 or 55*C which is well below the limiting temperature.

Conclusions.

The motors will operate satisfactorily under accident conditions without exceeding mechanical or thermal limitations on any part of the motor.

7

Southern Calforn/e Ed/son Company P 0 OND go 2'2' w*aL6UT GROVt AVCNuC osCMCAO eAuo*0.A *1770 June 27, 1988 Mr. Barry Craig Westinghouse.Electric Corporation 9095 Telstar Avenue El Monte, California 91731

Subject:

Overload Operation of Westinghouse Induction Motor San Onofre Nuclear Generating Station, Unit 1 As discussed with Mr. J. McCarthy and Mr. S. Bansal on June 27. 1988, we would like to request a quotation for an analysis on overloading safety related Westinghouse induction.notors. The nameplate rating of the motors are as follows:

Charging Pump Motors MGBA and MG88 Horsepower: 600 Voltage: 4160V, 60 Hz, 3-phase FLA:

72A, LRA: 700A Frame: 688.5-11 NEMA Code Letter: K Service Factor: 1.15 Insulation Class: 130 0C Style: 165Fl5619 Serial No.: 2S-65 The purpose of the analysis is to determine whether the motors can be operated at at-least 136% of full load rating for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, followed by 115% for 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> and 100:

for indefinit time. The analysis should cover the operation of a motor as a whole (mechanical and electrical components). If the motor can not be operated at 136%, the maximum allowable overload should be determined. Certified documentation and supporting data should be included.

Completion of this work is required within two weeks.

Your quotation is expected by June 29, 1988.

If you have any questions, please contact me at (810) 302-7496.

Sincerely,

n. Stawniczy

Southern Ce/famle EdIson Company r 0 Don SsI WALNUT @itOvC AVENUL SOU MPAD. CALIrORNIA 01770 June 29, 1988 Mr. Barry Craig Westinghouse Electric Corporation 9095 Telstar Avenue El Monte, CA 91731 Dear Mr. Craigs SUBJECTs Additional Information On Induction Notor Overload Operation Ban Onofre Nuclear Generation Station, Unit 1 As discussed with Kr. J. Earim on June 29, 1988, we are transmitting the following additional information on the environmental conditions seen by the charging pump motors:

Normal Accident Temperature -

80 104 Pressure - Pale 0

1.0 Relative Numidity -

4 60 100 Accident conditions will be present during the 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and 720 Hours specified for overload conditions-This information was referenced from the etzrof it Design Criteria Nanual, Rev. 6, Vigure V-9.

7f you have any other questions, please contact me at (18) 302-7496.

Sincerely, All n. Thiel

• c J* Karia L. Elder

Southem calf omI Edison Company 2Sa WALNUT OROVC AVCNUC ftQSCMCAD. CALIWORNIA 177o July 1. 1988 Mr. Lee Elder Westinghouse Electric Corporation 9095 Telstar Avenue El Monte, CA 91731

SUBJECT:

Revised Overload Operation San Onofre Nuclear Generating Station. Unit 1 Due to revised flow and environmental conditions, the following overload and ambient figures should now be evaluated:

136% of full load rating for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 125% of full load rating for 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> Ambient Temperature - 8OOF If the motor cannot be operated at the 125% of full load rating for 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br />, the maximum allowable overload value should be determined. Please provide a revised schedule.

If you have any questions, please contact Mr. Allen Thiel at (818)302-7496.

Sincerely, 4 G. Stawnicay cc: J.

arflk