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ACCESSION #: 9608120083 NOTE: This text document was processed from a scanned version or an electronic submittal and has been processed as received. Some tables, figures, strikeouts, redlines, and enclosures may not have been included with this submittal, or have been omitted due to ASCII text conversion limitations. In order to view this document in its entirety, you may wish to use the NUDOCS microfiche in addition to the electronic text. Limitorque Corporation 5114 Woodall Road o P. O. Box 11318 o Lynchburg, VA 24506-1318 Telephone (804) 528-4440 o FAX (804) 845-9736 LIMITORQUE TECHNICAL UPDATE - 93-03 SUBJECT: Reliance 3-Phase Limitorque Corporation Actuator Motors (Starting Torque @ Elevated Temperature) REFERENCE: Potential 10CFR21 Condition Dated May 13, 1993 (Attached) Issued September, 1993 The purpose of this update is to provide guidance in addressing the referenced document. 1. 550/575 Volt 3-Phase - The tabulated data presented in the referenced document is applicable to 550/575 volt, 3-Phase Reliance motors. 2. Motor Applicability - The tabulated data presented in the referenced document is applicable to all Reliance 3-phase motors. The motor start torque, no-load speed, and frame size must match that given in the tabulation, e.g.: Existing Reliance 230/460, 3-phase, 60 Hz, 100'#, 1800 RPM, 210 Frame motor design curve unavailable. From the tabulation, percent current loss is 17.8 percent, and percent torque loss is 13.1 percent when subjected to a 155 degrees C increase in temperature. 3. Deration Start Temperature - The torque reduction is to be applied at temperatures >40 degrees C (104 degrees F). The tabulation details percent loss over a 155 degrees C change in temperature (i.e., from 25 degrees C to 180 degrees C). The percent torque loss per degrees C for a 10'#, 1800 RPM, 56 Frame motor is: 27.7% = 0.179% / degrees C ----- 155 degrees C The percent torque loss for this motor operating in 100 degrees C ambient is: (0.179%) (100 degrees C - 40 degrees C) = 10.7% 4. Temperature Rise With Motor Energized - Reliance 3-phase motors are designed with thermal characteristics that result in =75 degrees C temperature rise in: a) 15 minutes @ full load running torque. Page 1 of 2 Limitorque Corporation Technical Update 93-03 b) 10 seconds @ locked rotor. A typical valve stroke time of 30 seconds will increase the motor temperature as follows: Equation omitted. The above example is simplistic and is given only to show that the motor temperature rise associated with stroking the valve is insignificant. However, applications that allow the motor to draw locked rotor current until the system or valve stabilizes must be addressed. A 5 second duration at locked rotor current will result in a temperature increase of >= 37.5 degrees C. It should be noted that continual diagnostic testing will increase motor temperature and decrease output torque and thrust. 5. Motor Speed at Elevated Temperature - Elevated temperature will reduce the motor full load speed. The speed reduction is minimal (nearly equal to 2% or 3%) from 25 degrees C to 180 degrees C. 6. Limitorque Corporation Sizing Equation - The standard sizing equation required the use of a 0.9 application factor. If the motor terminal voltage is less than 90 percent, this factor may be revised to 1.0. As before, there is no reduced voltage factor down to 90% voltage but below 90% voltage the square of the percent voltage available to rated motor voltage must be applied. 7. Misprint in Referenced Document - The 2'#, 1800 RPM, 56 Frame motor of the tabulation is a 48 frame motor. 8. Additional Motor Data: Start/RPM/Frame % Current Loss % Torque Loss 1'# / 900 / 48 30% / 155 degrees C 19% / 155 degrees C 2'# / 900 / 48 30% / 155 degrees C 19% / 155 degrees C 175'# / 3600 / 256 16.7% / 155 degrees C 9.9% / 155 degrees C 150'# / 1800 /256 15% / 155 degrees C 12% / 155 degrees C P. McQuillan Nuclear / Special Projects Manager Page 2 of 2 Limitorque Corporation 5114 Woodall Road o P. O. Box 11318 o Lynchburg, VA 24506-1318 Telephone (804) 528-4440 o FAX (804) 845-9736 May 13, 1993 U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Document Control Desk Re: Potential 10 CFR 21 Condition Subject: Reliance 3[symbol omitted] L. C. Actuator Motors (Starting Torque at Elevated Temperature) Limitorque Corporation has completed an evaluation of the subject motors. The results of this evaluation should be utilized to determine actuator operability at motor temperatures of 25 degrees C through 180 degrees C. The motor starting torque decreases with increasing temperature thereby decreasing actuator output torque. This condition could potentially be reportable depending on the operating practice of the license. Therefore, pursuant to the requirement of 10 CFR Part 21, herein provided is notification of a potential defect in Limitorque Corporation supplied motor actuators or motors supplied as spare parts. Identification of Basic Component The affected component is the Reliance 3[symbol omitted] A.C. motor that provides input power to actuator types SMB/SB/SBD 000 through 5 and SMB 000 through 5/HBC 0 through 7 combinations. Discovery Date The discovery date of this potential defect was July 27, 1989. Nature of the Defect The electrical characteristics of the Reliance 3[symbol omitted] A.C. Limitorque Corporation valve actuator motor are temperature dependent and locked rotor torque and locked rotor amperage will vary with motor temperature. Typically locked rotor torque and locked rotor amperage decrease as motor temperature increases. The attached tabulation details both parameters percentage changes in the temperature range of 25 degrees C to 180 degrees C. The percentage change is linear with respect to temperature for parameters with baseline data at 25 degrees C. Page 2 May 13, 1993 Potential Part 21 Condition The tabulation provides data that is relevant to standard Limitorque Corporation motor designs. The user must ensure that the motor performance curve number shown on the tabulation (e.g. M2735A) is applicable to the motor that is undergoing analysis. If this data is not available, the licensee may furnish the applicable motor identification numbers to Limitorque Corporation in order to make this determination. The following guidance is offered: 1. Credit should be taken for the locked rotor amperage decrease which will result in a higher available motor terminal voltage. 2. Motor temperature rise due to prior motor energization and motor run time (valve strike time) must be accounted for. 3. The tabulated data is expected to also predict 550/575 V 3[symbol omitted] 15 minute duty motor performance. The starting torque rating, no load speed and frame size of the 550/575V motor must match the attached data to allow this analysis. The licensee is requested to provide the motor identification numbers to Limitorque Corporation to verify this assumption. 4. The tabulated data is based on analysis by Reliance Electric. Limitorque Corporation performed testing on two motor designs (quantity of 5 motors) which validated the analysis. Equipment Affected 1. Same as the basic component identification. 2. Previously supplied technical data that may be used as the basis for operability justification. Where applicable this data should be revised to account for the applicable elevated temperature effects. Licensee Corrective Action Ensure operability justification considers the effect of motor performance at the applicable motor temperature. Limitorque Corporation Corrective Action Revise the selection procedure for safety related actuators, motors, and technical data packages to account for motor performance at the applicable motor temperature. Page 3 May 13, 1993 Potential Part 21 Condition A copy of this notification has been sent to the Nuclear Regulatory Commission (NRC) under a separate cover letter. Any questions or clarifications regarding the above notification may be directed to P. McQuillan, Nuclear/Special Projects Manager at (804) 528- 440 Ext. 714. Signed: I. E. Wilkinson Vice-President of Engineering Attachment cc: T. Mignogna Part 21 Notification File Table "Current/Torque Changes from 25 to 180 Centigrade" omitted. ATTACHMENT Part 21 May 13, 1993 LIST OF RECENTLY REPORTED PART 21 ISSUED 10 CFR 21 NRC Evaluation Report Number Topic Date 36 Torque Switch Groove Pin 04/03/91 37 Worm Gear Failures 08/04/92 40 Declutch Lever Seismic Test Resonance 12/07/92 41 SBD 1 Bolt Thread Engagement 10/05/92 43 Failure to Comply - L/C failed to 05/10/93 issue the required interim reports to the NRC open more than 60 days *** END OF DOCUMENT *** >