Part 21 Report - 1996-890
ACCESSION #: 9608120083
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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 ***
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