GOOD CAN SOMEONE HELP ME CAT SR4 REGULATOR REPLACEMENT BY VR6(A) 3

[JAME01]

Hello everyone, I have a very serious problem after removing the avr cat sr4 (9Y8400) that generated very unstable voltage. I replaced it with the vr6, but this gave me a worse headache, it was installed in the SE way but when generating for 2 seconds the protection fuses opened, 12 amp, the configurations are fine in the wiring, but I do test tests on the output of the vr6 with bulb output between f1 and f2 and it shows 130VOL DC, with 90 vac external power input, it looks fine but when I place this avr vr6(a) the fuses in the generator. between F1 and F2, there is 4ohm. but vr6 manual pdf does not mention that feature to me. I request a lot of help please.

 

[edison123]

Measure your exciter field DC resistance, which should be close to (exciter volt/exciter amps). Shorted exciter field turns would have a very low resistance, which can overload your AVR leading to its trip.

Also, megger the exciter field at 500 V. It should be more than 1 Megohm.

Muthu

http://www.edison.co.in

 

[catserveng]

If you are replacing a failed VR3 AVR (9Y8400), then you have a pretty old SR4 generator. 3 out of 4 VR3's I replaced in the field over the years died as a result of a problem external to the AVR (and I replaced a lot).

If you're failing the input fuses either the input voltage is too low or the AVR is going full field.

Older SR4's used a tapped set of leads from the windings for the 240VAC supply to the AVR, when you start the unit with the fuses in, does the supply voltage come up? Newer SR4's had a small transformer. Do you know how you're AVR is getting the power?

Have you done a full set of diagnostic tests on the generator? Includes a Megger test of the main stator and rotor and the exciter field. And testing the diodes and surge suppressor.

4 Ohms is in the normal range for exciter field resistance of an SR4.

After you FULLY test the generator end, and if no problems found, I'd recommend getting three good quality DMM's with MIN/MAX record features, set the ranges to the maximum expected voltages, connect one meter to the power input, one meter to the sensing input and one meter to the field output. As the generator ramps up in speed and power gets above about 50VAC on the power inputs, the field output will go to near full output and as sensing comes up closer to rated the field output will drop of and settle out to around 10-12VDC at rated voltage. In your case popping the fuses in a short time having the MIN/MAX data from the meters will help you identify possible problems. DO NOT put in bigger fuses! Seen that done way too many times.

I've attached a presentation I used to do for customers and dealers, you may find it helpful.

MikeL

 

[JAME01]

Hello, good evening, today I am doing my usual job and I am only two days late.
I tell you, the new avr vr6 has a manual that does not allow me a guide, since BASLER AVC63-12, WHEN PERFORMING TESTS ON THE AVR VR6 AS THE MANUAL SAYS, IT WORKED, on a test bench, but as I have told you, I put vr6 and the fuses open, I put the old avr back in and it works but the voltage is unstable even when changing the new 10k potentiometer (the original one doesn't break the fuses).
EXITATRIS FIELD IS 4 OHM, here I leave you information about the original manual of the new vr6, without success.
The field f1 and f2 were tested with meguer and ok, tests were carried out on the diodes and ok. The generator is fine, but the vr6 test does not pass mounted on the generator. I will show you some photos of the VR6 wiring, how it was installed, for a few seconds it generates but it shorts out or the fuses open. Another data on terminal 22 rises 65 amps during those 2 to 5 seconds, but the panel voltage is 227 volts during that instant before the fuses open.

I tested the image in the diagram with 120 volts (the test passed)..The second image corresponds to AVR Basler specifications on ohm exitatris.... the color images are combinations that I also made for testing but installed in a generator, those images are identical tested connections found on the internet, maybe making those configurations The AVR opens the fuses.

If anyone gives me more suggestions please I will be grateful.

 

[edison123]

Let's start simple. With the generator at standstill, power your AVR from an external source. If the AVR fuses blow up, your exciter field winding is gone.

Muthu

http://www.edison.co.in

 

[waross]

If the exciter resistance checks out, it is probably an issue with the main field.
Or, as edison says, an exciter problem.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[waross]

Try exciting your exciter with a 12 Volt car or truck battery.
By the way, I hope that you don't have the voltage adjustment turned all the way up.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!