Rigid RD90800s 8kw 3600rpm generator

[carlb23]

pulled to stator yesterday and had a good look at the winding.  I could see some dark/burnt marks on the harmonic winding and when tested for continuity the circuit is open.

The 4 wires on the plug that go to the avr are white, green, blue and blue.  The blue wires are the harmonic winding and the green and white are sense wires from L1 and L2.

I did another test using the variac  and put a 5kw load on the generator with resistance heaters.

Powering the variac from the grid i was able to put a 5kw load on the generator  using resistance heaters and the engine wasn't even working hard (14hp Subaru)

After all of this testing i believe that the st115 avr from Tom should work fine and i will call him tomorrow and place an order.

I will update this thread after getting the avr and let all know how it worked out.

Thanks for all the help guys

Carl

[carlb23]

Received the st115 AVR from Tom @ CGG yesterday.  Hooked it to bypass the harmonic winding based on the drawing that Tom sent along with the AVR.   Worked like a charm, on startup holding a steady 110Vac/220vac.  Gave the variable resistor a little turn and got the output to 122/244 Vac no load. 

With a 4.5kw load the voltage stayed at 120/240vac steady.   Looks like this avr is a good fix for gen heads with a bad harmonic winding @ a very reasonable price.

Tom spent a lot of time with me on the phone to help fix this problem and I can't say enough good things about my experience with both Tom and CGG.

We need more people and companies in this country like Tom and CGG.



Carl

[BruceM]

Bravo for a great job of troubleshooting and repair, Carl!

[carlb23]

Update,

The AVR fixed the bad harmonic winding problem and was great with resistive loads up to 6kw on natural gas, but when i tried to start my 3.5 ton Heat Pump the voltage sagged to low because of the large inrush current needed and it would not start.  This problem is surely due to the fact that the AVR takes it voltage to send to the brushes from the L1 winding (which it has to with a bad harmonic winding)on the generator head and the large load is pulling the voltage down to far so that even the AVR (which is functioning properly) can't pickup it back up. This is not an issue with the AVR as it is working properly.

I decided to try a 5-2-1 CSR-U-2  three wire hard start kit on my heat pump.   I installed the hard start kit and the generator now starts the 3.5 ton heat pump with no problem.  After startup the generator which i have set to 123vac comes right back up to 123 vac.  The heat pump when running is only drawing 12 amps per leg @ 226vac or about 2.7kw.

Just for fun i decided to try to start the heat pump with my 6/1 and 4kva head.  To my utter amazement the Listeroid running on diesel/natural gas started  and ran the heat pump but with some voltage sag down to 116vac which is quite acceptable.   


I would recommend this hard start kit to anyone who need a little extra grunt when running your generator to power central A/C or even a large motor with a run capacitor.

Carl

I guess i could always tweek the governor a bit if i needed the 6/1 to run the heat pump.

[Tom]

I would recommend that someone use a prime mover with large flywheels that store lots of energy if they need to start large loads.  A 4.4kw B&S genset I had would not start my smallest air compressor, the Listeroid / st5 combo starts my large air compressor without flinching.