United States Nuclear Regulatory Commission - Protecting People and the Environment

1220 S. Washington St., Rocky Mount, NC 27801
P.O. Box 1928, Rocky Mount, NC 27802-1928
Telephone: 252/977-2720
Fax: 252/446-1134

June 19,2001

U.S. Nuclear Regulatory Commission
Document Control Desk
Mail Stop OP1-17
Washington, DC 20555

Subject: 10CFR2I Reporting of Defects and Non-Compliance
Engine Systems, Inc. Report No. 10CFR21-0082

                     Woodward electronic controls with electrolytic capacitors

Dear Sir:

The enclosed report addresses a reportable notification about service life of electrolytic capacitors in Woodward controls.

A copy of the report will be mailed to all of our nuclear customers.

Please sign below, acknowledging receipt of this report, and return a copy to the attention of Document Control at the address below (or, fax to number 252/446-1134) within 10 working days after receipt.

Yours very truly,


Susan Woolard
Document Control

Please let us know if ANY of your mailing information changes - name of recipient, name of company/facility, address, etc. Mark the changes on this acknowledgment form and send to us by mail or FAX to the number above.

    RECEIVED: __________________

DATE: ___________________

                                                    Quality Performance With Pride

Report No. 10CFR2I-0082
Rev. 0: June 18, 2001


COMPONENT: Woodward electronic controls with electrolytic capacitors

SYSTEM: Diesel generator and turbine control systems

CONCLUSION: Reportable in accordance with 10CFR21.

PREPARED BY: _____________________________ DATE: _________
                                           Engineering Manager

REVIEWED BY: _______________________________ DATE: ________
                                          Quality Assurance Manager

REPORT NO. 10CFR21-0082
REVISION 0: 6/18/01             
PAGE: 1 0F 2                         


Engine Systems Inc. (ESI) has performed an investigation of a Woodward 2301A load sharing and speed control failure which occurred at Florida Power and Light - Turkey Point. In August 2000, a 2301A control (p/n 9903-337) experienced a failure of the control's power supply capacitor (device C17) which rendered the control inoperable. FP&L performed a preliminary investigation and found that Washington Public Power had also experienced a similar failure on two of their 230lA controls; one in June 1994 and another in December 1995. A summary of the capacitor failures is listed below:

Site Device Part No. Date Code Manufacture Date Failure Date
FP&L C17 1660-111 8804 Jan1988 Aug2000
WP C17 1660-111 8634 Aug1986 June1994
WP C17 1660-111 8634 Aug1986 Dec1995

FP&L had a failure analysis performed on their failed capacitor by Seal Laboratories. The analysis concludes that the most likely cause of the failure was caused by electrolyte contamination from a halogenated solvent which may have entered the capacitor during solvent cleaning of the circuit board as part of the control's manufacturing process. FP&L also provided a copy of WP's failure analysis on one of their failed capacitors performed by HI-REL laboratories. The HI-REL analysis arrived at a similar conclusion regarding solvent contamination.

As part of our investigation, ESI contacted Woodward's capacitor supplier to obtain life expectancy and shelf life information for their electrolytic capacitors. Life expectancy can vary from a maximum of 15 years to a minimum of 5 years depending upon storage conditions, operating environment, etc.. The manufacturer recommends are 5-7 year replacement interval for conservatism; this includes time in storage plus time in service. In addition, for units in storage, the capacitor must be reformed every 18-24 months by applying system voltage.

Electrolytic capacitors are typically used in power supply filtering applications. For the 2301A, capacitor C17 is used on the output side of the control's 125V to 20V power supply. The 2301A also contains an electrolytic capacitor (device C16) on the input power side of the power supply. ES l's investigation into this issue focused primarily on the Woodward 2301A control. It should be noted, however, that Woodward also utilizes electrolytic capacitors in some of their other controls; these include the DRU (speed reference unit) and the 700 series controls.


All three of the failed capacitors had service lives that exceeded the manufacturer's 5-7 year replacement interval. While the failure analysis reports of both Seal Laboratories and HI-REL Laboratories indicate that contamination from use of halogenated cleaning solvents may have contributed to the capacitor failures; ESI believes that the capacitors simply reached their end of life. If contamination did occur, it did not significantly affect the capacitor performance and/or life.

The purpose of this notification is not to report a defect, but is issued to alert users of a defined life for electrolytic capacitors. These capacitors are known to be used in Woodward 2301 A, DRU and 700 series controls. Woodward has manufactured more than 40,000 2301A controls since its introduction in 1983 and only a limited number of capacitor failures have been report. Of the 2301 A's in nuclear service, only the three (3) failures, discussed above, have been reported. No capacitor failures of the DRU and the 700 series controls in nuclear service have been reported.

REVISION 0: 6/18/01             
PAGE: 2 0F 2


Woodward electronic controls containing electrolytic capacitors. These include the 2301A load sharing & speed control, the DRU speed reference unit and the 700 series speed control.


Because of the variety of part numbers and configurations of Woodward electronic components, this notification will be sent to all ESI nuclear customers


ESI recommends replacing the control's electrolytic capacitors every 5-7 years from the manufacture date of the capacitor. The capacitor manufacture date is identified by a date code stamped on the capacitor (e.g. 8807 indicates the 7th week of 1988). In addition, the electrolytic capacitors of controls in storage must be reformed every 18-24 months. Reforming is accomplished by applying rated voltage to the control's input power terminals for a period of 24 hours. Controls in service normally have input power continuously applied (or as a minimum, input power is applied during periodic surveillance testing of the prime mover) and therefore, a separate reforming operation is not required.

Suspect controls can be sent to ESI for determination of electrolytic capacitor date code, capacitor replacement and periodic power-up. All future controls shipped from ESI will have the electrolytic capacitor date code identified on the front surface of the control to assist in determining replacement/refurbishment intervals. Contact Customer Service for further information about returning a control.

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