CAT AVR TYPE D.V.R. FOR A SR4 GENERATOR 2

[matuk]

HI, WE HAVE A SR4 GENERATOR WITH A DVR AVR, RECENTLY WE CHANGE IT WITH A SIMILAR OTHER, BECAUSE THE GENERATOR ARE TRIPING WITH OVERVOLTAGE 750 VCA ( 480 VCA NOMINAL ) ITS WORKS FOR A WHILE AND THEN THE SAME FAILFURE, IN TERMINALS 20-22 WE HAVE 380 VCA F1-F2 90 VCD THATS THE ONLY MESUREMENTS WE HAVE, THE SENSIG VOLTAGE IS DIRECTLY FROM LV LEADS. CAN YOU HELP US PLASE.

 

[waross]

You may have a broken or loose wire in your sense wiring to the AVR.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[rbulsara]

What is the model of the DVR?
The issue may be outside the DVR.

Essentially there is not enough information to comment and there are too many variables. You need a CAT field service technician on site.

Check all connections and wiring, settings in the software if applicable, such as VT ratio. You may be better off using VTs with 120V secondary.



Rafiq Bulsara

http://www.srengineersct.com

 

[catserveng]

The most common causes of a DVR going to full field. In order of likely occurance,

Loss of sensing

Open in droop CT circuit

DVR failed

Loss of 24 VDC to DVR

CAT offered the DVR in three possible sensing voltage ranges, 120, 240 and 480. All three used nominal 120 VAC power input from either PM or transformer for SE

480 was least common, 240 was most common, 120 was usually only seen on MV (2400 to 13,800V) machines with sensing VT's

CAT manual number is SENR5833, sorry I don't have a copy anymore, try your local CAT dealer for a copy.

Hope that helps

 

[matuk]

Is usual that a DVR fail and it works again later? I was check and now is working ok.

 

[catserveng]

An intermittant failure on a DVR usually indicates it's internal power supply is bad. Can also be the result of a problem with the 24 VDC power supply to the DVR.

There was also a series of part numbers several years ago that had a problem with the internal sensing connections that could be a cause of the problem you're seeing, ut would likely have been corrected when you put on the newe DVR.

Some 4 and 6 lead machines had center tap sensing that was problematic after some years in service, the field fiw was usually a 2:1 sensing transformer.

What is your rated sensing voltage, should be on the part number tag of the DVR? If you can't read it what is part number of DVR?

 

[matuk]

The part number is 155-3835

serial number UEMDE 6498

Ratio of output voltage to sensing voltage is 2.0

Generator output voltage 480 V