Printer Friendly

Overheating circuit breakers.

Possible overheating circuit breakers (AQB-A402, AQB-LF402, and NQB-a402) may occur due to the absence of or excessive lock tight on the moving main contact assembly, interference of the moving main contact assembly with a molded "rib", or improper screws in the moving main contact assembly. A recall of these circuit breakers by the OEM has been instituted because of the overheating problems. Recalled circuit breakers were manufactured prior to 1 FEB 2003 or have a serial number less than 008210. Circuit breakers repaired under the recall were stamped with an "R" after the serial number. Circuit breakers that were not repaired under the original recall may still be installed in Los Angeles, Ohio and Seawolf class submarines but not aboard Virginia class submarines. The circuit breakers are form, fit, and function replacements for the obsolete AQB-A400, AQBLF400 and NQB-A400 circuit breakers and may be installed in the following locations: SSBN/SSGN 726 class--5S, 6S, SWS 70KW rectifier control units. SSN 21 and 22--1S, 2S, 1SA, 2SA, 5S, and 6S. SSN 23--1S, 2S, 1SA, 2SA, 5S, 6S 5SC, 6SC and the shunt trip enclosure for MMP external power. SSN 688 class--1S, 2S, 5S, 6S. SSN-766, SSN-771, SSN-772, SSN-773--1S, 2S, 5S, 6S, 5SD, and 6SD.

Requested TYCOMS to direct their units to inspect switchboards for AQB-A402, AQB-LF402 and NQB-A402 circuit breakers. If found, ships force should note the serial number, SPD part number (ETN), and date of manufacture. The serial number is stamped in black on the face of the breaker and on the side of the circuit breaker base. The nameplate on the face of the breaker shows the type of breaker, the SPD part number (ETN number), and year of manufacture. For circuit breakers without motor operators, the nameplate and serial number will be visible once the switchboard front cover is removed or opened. For circuit breakers with motor operators, remove the motor operator to see the circuit breaker nameplate and serial number. Ships force should complete the inspection during their next in-port period.

1. Report breaker type, serial number, SPD part number (ETN), and date of manufacture to ISIC. ISIC's will report completion of inspection and conditions found to the TYCOM for submittal to PMS 392T.

2. Coordinate with the ISIC to replace any circuit breakers that have not been repaired.

3. If the breakers cannot be replaced immediately, the ship should coordinate with the PMT to conduct thermal imaging of affected circuit breakers as soon as practicable. If the thermal imaging indicates higher than normal operating temperatures, the breakers should be placed on limited service until replaced.

4. Submit a quality deficiency report (QDR) with the original REQN number. If the circuit breaker was not requisitioned by ships force, coordinate with installing activity to determine REQN number. If circuit breaker was not obtained through supply system, then no REQN number required. The failure description on the QDR should state that the circuit breaker has been recalled by the manufacturer and is being returned for free, OEM inspection. REF: COMNAVSEASYSCOM Washington DC 281201Z DEC 10.

COPYRIGHT 2011 U.S. Naval Safety Center
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2011 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Electrical/Mechanical
Date:Jan 1, 2011
Previous Article:Atmospheric contaminants.
Next Article:E-blast news.

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters