ENS 53600
ENS Event | |
|---|---|
04:00 Jul 19, 2018 | |
| Title | Part 21 - Motor Operated Potentiometer Defect |
| Event Description | A batch of Motor Operated Potentiometers (MOPs) supplied by ESI [Engine Systems Inc.] were found to contain motors that, as they accumulate run time, exhibit increasing current draw and eventually exceed the MOP circuit allowance. Consequently, the motor operation becomes erratic which leads to a sluggish MOP. The MOP is used in a safety-related system to control emergency diesel generator (EDG) output voltage. Failure of the MOP to operate properly can negatively affect the EDG output voltage which affects associated components required to safely shutdown the nuclear reactor.
ESI will revise the test procedure to incorporate an extended run time while trending the motor for any adverse changes. This will be completed within 30 days and will prevent reoccurrence. For Catawba, any MOPs from this batch are considered suspect and may be returned to ESI for rework or replacement. For units installed, the motor performance should be assessed prior to continued use. The voltage measured across terminals 3(-) and 4(+) while the MOP is operating should remain steady within a range of 22.8 to 25.2 VDC. Any step change or reduction in voltage is an indication of motor deterioration. The root cause of the excessive current draw was found to be build-up of carbonaceous deposits between the commutator sections of the motor either from the carbon brushes, contamination, or a combination of the two. As the motor accumulated run time, the deposits propagated to the point of a low resistance path between commutator sections which are wired to the armature poles. This affected the magnetic field within the motor which had a direct impact on motor performance. ESI has limited the issue to a single date code of motors supplied within a single batch of MOPs, as listed. Motor Operated Potentiometer, PIN 72-07900-100-ESI. Duke Energy Catawba, Customer PO 196046, Qty: 6, ESI Serial Number 3013905-1.1-1 thru 6, MOP Serial Number - H01931980, H01995582, H01995584, H01995585, H01995586, H01995587, C-of-C Date: 5/30/2015. |
| Where | |
|---|---|
| Engine Systems, Inc Rocky Mount, North Carolina (NRC Region 1) | |
| Organization: | Engine Systems, Inc |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+1332.32 h55.513 days <br />7.93 weeks <br />1.825 months <br />) | |
| Opened: | Dan Roberts 16:19 Sep 12, 2018 |
| NRC Officer: | Steven Vitto |
| Last Updated: | Sep 12, 2018 |
| 53600 - NRC Website | |
Engine Systems, Inc with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
WEEKMONTHYEARENS 565382023-03-28T04:00:00028 March 2023 04:00:00
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