Information Notice 1993-74, High Temperatures Reduce Limitorque AC Motor Operator Torque
K-/
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
September 16, 1993
NRC INFORMATION NOTICE 93-74: HIGH TEMPERATURES REDUCE LIMITORQUE AC MOTOR
OPERATOR TORQUE
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees that high ambient temperatures can reduce ac motor
torque capability in Limitorque motor operators.
It is expected that
recipients will review the information for applicability to their facilities
and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice are not NRC requiyements;
therefore, no specific action or written response is required.
Background
In order to size a motor operator to a given valve, the expected operator
torque capable of being developed under design-basis conditions is calculated.
The operator torque output is directly related to the torque output of the
operator motor.
For dc motor operators, Limitorque has published derating
factors that are applied to high ambient temperature applications.
However, until recently, no derating information was available for Limitorque motor
operators equipped with ac motors.
DescriDtion of Circumstances
In response to NRC questions, Limitorque Corporation established a test
program to evaluate whether elevated ambient temperatures could significantly
affect ac motor output torque.
In October of 1992, Limitorque completed
testing of five ac motors. This testing indicated that ac motor stall torque
values decreased significantly with increasing ambient temperatures.
The
measured torque reductions ranged from 14 to 25 percent for ambient
temperature increases from 24°C [75°F] to 1690C [336*F].
contracted with its main motor supplier, Reliance Motor Co., to calculate the
expected stall torque reduction for all Limitorque/Reliance ac motor designs.
On May 13, 1993, Limitorque issued a report about a potential 10 CFR Part 21 condition.
The report contained a tabulation of motor types and expected
torque reductions for ambient temperature increases from 25*C [77 0F] to 1800C
9309100374 x
IotNc4 c 2
~°>
10?- /I.c
September 16, 1993 [356°F].
This data is given in Attachment 1. Limitorque has since indicated
that the torque reductions would be applicable only for motors in ambient
conditions above 40*C [1040F] as the motors are designed to deliver full rated
torque up to 40C [104'F].
Limitorque has stated that the torque reduction is linear with respect to
temperature.
The Limitorque table also contains information on the expected
reduction in locked rotor current at elevated temperatures. The reduced
locked rotor current would provide a slightly higher motor terminal voltage.
Although this would improve the calculated reduced voltage motor performance, it would not compensate for the torque reduction resulting from an elevated
temperature.
Limitorque further stated that motor temperature rise as a
result of prior motor energization and motor run time (valve stroke time) must
be accounted for.
Additional information concerning motor operator performance can be found in
NRC Inspection Report 99900100/93-01 issued June 28, 1993.
This information notice requires no specific action or written response.
If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
ast
@
A,
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: Jeffrey B. Jacobson, NRR
(301) 504-2977
Thomas G. Scarbrough, NRR
(301) 504-2794 Attachments:
1. Current/Torque Changes from 25 to 180 Centigrade
2. List of Recently Issued NRC Information Notices
-
IN 93-74 September 16, 1993 This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Orignal signed by
Al Chaffee for/
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts:
Jeffrey B. Jacobson, NRR
(301) 504-2977
Thomas G. Scarbrough, NRR
(301) 504-2794 Attachments:
1. Current/Torque Changes from 25 to 180 Centigrade
2. List of Recently Issued NRC Information Notices
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OFFICE:
- RSIB:DRIL
- SC:RSIB:DRIL
- C:RSIB:DRIL
- D:DRIL:NRR
NAME:
JBJacobson
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DATE:
08/12/93
08/12/93
08/13/93
08/16/93
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DATE:
1 08/23/93
09/01/93
09/01/93
09/08/93
09//193 Document Name: 93-I4.IN
Attacment 1 IN 93-74 September 16, 1993 Curiznt/Torque Changes from 25 to 180 Centigrade
'a#1 P8
2'#/1800
5'#/1800
5'#/1800
7.5'#J1800
10'#/1800
15'#/1800
25'#/1800
40'#/1800
60'#/1800
60'#/1800
80'#/1800
100'#/1800
200'#/1800
250'#/1800
300'#I1800
2'#/3600
5'#13600
5'#/3600
7.5'#/3600
10'#13600
15'#/3600
25'#13600
40'#/3600
40'#/3600
60'#/3600
80'#/3600
100'#/3600
150'#/3600
200'#/3600
250'#/3600
300'#/3600
400'#/3600
Frame
56
48
56
56
56
56
56
56
58
180
210
210
256
256
326
48
48
56
56
56
56
56
56
180
210
210
256
256
326
326
326
365 Mu2e3#
M2735A
M2734 M1658 M2925 M1468 M1476 M1480
M1488 M5204 SK-59454 SK-59423 SK-59419A
413018-03 M199 M1454 M1457 M1458 M1460
M1463 M4635 SK-59450
SK-59446 SK-59448 SK-34176 SK-34184 SK-34188 SK-34173 SK44171 SK44800-
% Current
27.8%
29.0%
21.8%
22.4%
26.9%
23.7%
23.1%
21.1%
20.8%
19.6%
16.1%
17.0%
13.5%
11.8%
11.7%
28.3%
27.7%
24.7%
27.6%
23.5%
19.2%
16.2%
27.9%
16.2%
18.2%
18.0%
14.1%
13.9%
10.5%
9.3%
10.8%
8.8%
% Torq
Loss
20.7%
18.6%
21.9%
5.7%
27.7%
23.1%
23.2%
23.4%
20.9%
18.2%
15.8%
13.1%
9.0%
6.9%
5.8%
16.0%
18.5%
26.8%
16.7%
30.8%
21.4%
24.1%
15.9%
11.8%
16.5%
18.3%
9.8%
10.0%
3.4%
3.4%
2.9%
-1.8%'
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Attachment 2
September 16. 1993
Page I of I
LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Date of
Information
Notice No.
Subject
93-73
Criminal Prosecution of
Nuclear Suppliers for
Wrongdoing
93-72
Observations from Recent
Shutdown Risk and Outage
Management Pilot Team
Inspections
93-71
Fire at Chernobyl Unit 2
93-70
Degradation of Boraflex
Neutron Absorber Coupons
93-69
Radiography Events at
Operating Power Reactors
licensees.
93-68
Failure of Pump Shaft
Coupling Caused by
Temper Embrittlement
during Manufacture
92-16,
Loss of Flow from the
Supp. 2
ResIdual Heat Removal
Pump during Refueling
Cavity Oraindown
93-67
Bursting of High
Pressure Coolant
Injection Stem Line
Rupture Discs Injures
Plant Personnel
93-66 Switchover to Hot-Leg
Injection Following
A Loss-of-Coolant
Accident in fres- surized Water Reactors
'I L
Operat'ng License
- Construction Permit
Issuance
Issued to
09/15/93 All NRC licensees.
09/14/93
All holders of OLs or CPs
for nuclear power reactors.
09/13/93
All holders of OLs or CPs
for nuclear power reactors.
09/10/93
All holders of OLs or CPs
for nuclear power reactors.
09/02/93
All holders of OLs or CPs
for nuclear power reactors
and all radiography
09/01/93
All holders of OLs or CPs
for nuclear power reactors.
08/23/93
All holders of OLs or CPs
for nuclear power reactors.
08/16/93
All holders of OLs or CPs
for nuclear power reactors.
(
08/16/93
All holders of OLs or CPs
for pressurized water
reactors.
IN 93-xx
September xx, 1993
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts:
Jeffrey B. Jacobson, NRR
(301) 504-2977
Thomas G. Scarbrough, NRR
(301) 504-2794 Enclosures:
1. Current/Torque Changes from 25 to 180 Centigrade
2. List of Recently Issued NRC Information Notices
C^i^ Dy-pA,4wIc rnnemitronra
OFFICE:
- RSIB:DRIL
- SC:RSIB:DRIL I *C:RSIB:DRIL
- D:DRIL:NRR
NAME:
JBJacobson
DPNorkin
EVImbro
CERossi
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08/13/93
08/16/93 I
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NAME:
TGScarbrough
RJKiessel
DGable
GHMarCus
K
BKGrimes
DATE:
1 08/23/93
9/ 1/93
9/ 1/93
9/,?/93
9 Document Name:
NKL1IN.3!0
for.
Additional information concerning motor operator performance can be found in
NRC kIspection /eport 99900100/93-01 issued June 28, 1993.
This information notice requires no specific action or written response.
If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: Jeffrey B. Jacobson, NRR
(301) 504-2977
Thomas G. Scarbrough, NRR
(301) 504-2794 Enclosures:
1.
Current/Torque Changes from 25 to 180 Centigrade
2.
List of Recently Issued NRC Information Notices
Document Name: nrcin.391
- Previously Concurred
OFFICE:
- RSIB:DRIL
- SC:RSIB:DRIL
- C:RSIB:DRIL
- D:DRIL:NRR
NAME:
JBJacobson
DPNorkin
EVImbro
CERossi
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08/13/93
1 08/16/93 VF_ IL._
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OFFICE:
- EMEB:DE
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C:OGCB:DORS
D:DORS:NRR
NAME:
TGScarbrough
RJKiesse
__77___
GHMarcus
BKGtimes
DATE:
08/23/93
09/) /93
09// /93
09/
/93
09/l g 3
IN 93-XX
August 18, 1993 On May 13, 1993, Limitorque issued a "Potential 10 CFR 21 Condition" report
which contained a tabulation of motor types and expected torque reductions for
ambient temperature increases from 250C to 1800C. This tabulated data is
attached as Enclosure (1).
Limitorque has since Indicated that the torque
reductions would only be applicable for motors in ambient conditions above
40°C as the motors are designed to deliver full rated torque up to 40C.
Limitorque has stated that the torque reduction is linear with respect to
temperature.
The Limitorque table also contains information on the expected
reduction in locked rotor current at elevated temperatures. The reduced
locked rotor current would provide a slightly higher motor terminal voltage.
This would improve the calculated reduced voltage motor performance, however, not nearly enough to compensate for the torque reduction due to elevated
temperature. Also, Limitorque stated that motor temperature rise due to prior
motor energization and motor run time (valve stroke time) must be accounted
for.
Additional information concerning motor operator performance can be found in
NRC inspection report 99900100/93-01 issued June 28, 1993.
This information notice requires no specific action or written response.
If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: Jeffrey B. Jacobson, NRR
(301) 504-2977
Thomas G. Scarbrough, NRR
(301) 504-2794 Enclosure 1:
Current/Torque Changes from 25 to 180 Centigrade
Distribution:
JBJacobson
DPNorkin
EVImbro
RPZimmerman
CERossi
BKGrimes
Central Files
DOEA R/F
RSIB R/F
- Previously Concurred_
I
OFFICE:
RSIB:DRIL
SC:RSIB:DRIL
TECH EDITOR
C:RSIB:DRIL
NAME:
JBJacobson*
DPNorkin*
EVImbro*
DATE:
08/12/93
08/12/93
08/ /93
08/13/93 OFFICE:
D:DRIL:NRR
E
D:DOEA:NRR
NAME:
CERossi*
TGScarbrough
BKGrimes
l
DATE:_08/16/93
08/1930
/93 I 08/
/93
8 As
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OFFICIAL RECORD COPY
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IN 93-XX
August 13, 1993 On May 13, 1993, Limitorque issued a 'Potential 10 CFR 21 Condition3 report
which cottlined a tabulation of motor types and expected torque reductions for
ambient temperature increases from 25"C to 180"C. This tabulated data is
attached as Enclosure (1).
Limitorque has since indicated that the torque
reductions wouMd only be applicable for motors in ambient conditions above
400C as the moto.ds are designed to deliver full rated torque up to 40*C.
Limitorque has stat
that the torque reduction is linear with respect to
temperature. The
torque table also contains information on the expected
reduction in locked rotor current at elevated temperatures. The reduced
locked rotor current wou'd provide a slightly higher motor terminal voltage.
This would improve the cal ulated reduced voltage motor performance, however, not nearly enough to compen ate for the torque reduction due to elevated
temperature. Also, Llmitorq
stated that motor temperature rise due to prior
motor energizatlon and motor r
time (valve stroke time) must be accounted
for.
Additional Information concerning
tor operator performance can be found in
NRC inspection report 99900100/93-01 ssued June 28, 1993.
This information notice requires no spe ific action or written response. If
you have any questions about the informa on in this notice, please contact
one of the technical contacts listed belo or the appropriate Office of
Nuclear Reactor Regulation (NRR) project ma ger.
Brian K. Gmines, Director1 .
Division of Operat
Office of Nucear Reactor Regulation
Technical contacts: Jeffrey B. Jacboson, NRR
(301) 504-2977
Thomas G. Scarbrough, NRR
(301) 504-2794 Enclosure 1:
Current/Torque Changes from 25 to 180 Centlgr e
Distribution:
JBJacobson
DPNorkin
EVImbro
RPZlmmerman
CERossi
BKGrimes
Central Files
DOEA R/F
RSIB R/F \\
- Previously Concurred
OFFICE:
RSIB:DRIL / SC:RSIB:DRIL
TECH EDITOR
C:RSIB:oRIL
NAME:
JBJacobson*
DPNorkin*
EVImbro*
DATE:
0812/93
[08/12/93
08/
/93
08/13/93 OFFICE:
D:DRIL:NRR
D:DOEA:NRR
lNAME:
C05;
BKGrimes
DATE:
08//ip93
08/
/93 I__Tat
______
__.____
OFFICIAL RECORD COPY
DOUMENT NAME:
G ;\\ INFONO I .d JJ
IN 93-XX
August 13, 1993 0 May 13, 1993, Limitorque issued a 'Potential 10 CFR 21 Condition" report
whi
contained a tabulation of motor types and expected torque reductions for
amble t temperature increases from 250C to 1800C. This tabulated data is
attach
as Enclosure (1).
Limitorque has since indicated that the torque
reductio
would only be applicable for motors in ambient conditions above
400C as th motors are designed to deliver full rated torque up to 400C.
stated that the torque reduction is linear with respect to
temperature.
e Limitorque table also contains information on the expected
reduction in 1c
-ted rotor current at elevated temperatures. The reduced
locked rotor curr t would provide a slightly higher motor terminal voltage.
This would improve he calculated reduced voltage motor performance, however, not nearly enough to ompensate for the torque reduction due to elevated
temperature. Also, Iitorque stated that motor temperature rise due to prior
motor energization and
tor run time (valve stroke time) must be accounted
for.
Additional information conce ing motor operator performance can be found in
NRC inspection report 99900100 3-01 issued June 28, 1993.
This information notice requires
specific action or written response.
If
you have any questions about the in Qrmation in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) proJed4 manager.
Brian . Grimes, Director
Divisioh of Operation Events Assessment
Office o#?Nuclear Reactor Regulation
Technical contacts: Jeffrey B. Jacboson, NRR
(301) 504-2977
Thomas G. Scarbrough, NRR
(301) 504-2794 Enclosure 1:
Current/Torque Changes from 25 to 180 Cent grade
Distribution:
JBJacobson
DPNorkin
EVImbro
RPZimmerman
CERossi
BKGrimes
Central Files
DOEA R/F
RSIB R/F
- Previously Concurred
_
OFFICE:
RSIB:DRIL
SC:RSIB:DRIL
TECH EDITOR
C:RSIB'.-DRIL
NAME:
JBJacobson*
DPNorkin*
Vlmbro
DATE:
08/12/93
08/12/93
08/
/93
08
93 OFFICE:
D:DRIL:NRR
D:DOEA:NRR
_
NAME:
CERossi
BKGrimes
DATE:
08/
/93
08/
/93
___________
_____________
OFFIIAL
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1
OFFICIAL RECORD COPY
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IN 93-XX
August 12, 1993 On Ma 13, 1992, Limitorque issued a "Potential 10 CFR 21 Condition" report
which ontained a tabulation of motor types and expected torque reductions
from 25 to 1800C. This tabulated data is attached as Enclosure (1).
Limitorqu
has since indicated that the torque reductions would only be
applicable or motors in ambient conditions above 40eC as the motors are
designed to eliver full rated torque up to 40C.
Limitorque has lso stated that the torque reduction is linear with respect to
temperature. Th Limitorque table also contains information on the expected
reduction in locatd rotor current at elevated temperatures. The reduced
locked rotor curren would provide a slightly higher motor terminal voltage.
This would improve t calculated reduced voltage motor performance, however, not nearly enough to
mpensate for the torque reduction due to elevated
temperature. Also, LimUtorque stated that motor temperature rise due to prior
motor energization and m or run time (valve stroke time) must be accounted
for.
Additional information conce ing motor operator performance can be found in
NRC inspection report 99900100 3-01 Issued June 28, 1993.
This information notice requires o specific action or written response. If
you have any questions about the i formation in this notice, please contact
one of the technical contacts liste below or the appropriate Office of
Nuclear Reactor Regulation (NRR) pro ct manager.
Brian K. Grimes, Director
Divisi
of Operation Events Assessment
Office
Nuclear Reactor Regulation
Technical contacts: Jeffrey B. Jacboson, NRR
(301) 504-2977
Thomas G. Scarbrough, NRR
(301) 504-2794 Enclosure 1:
Current/Torque Changes from 25 to 180 Ce tigrade
Distribution:
JBJacobson
DPNorkin
EVImbro
RPZimmerma
CERossi
BKGrimes
Central Files
DOEA R/F
RSIB R/F
OFFICE:
RSIB:DRIL
RIL
TECH EDITOR
RSI:DRILl
NAME:
JBJacobJ0#
r
o
Hhtnbk
DATE:
108/)I
J_____
_93
08/ /93
08/
939 OFFICE:
D:DRIL:NRR
D:DOEA:NRR
m
NAME:
CERossi
BKGrimes
\\
DATE:
08/ /93
08/
/93
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