So we finally got the vendor back with the load bank. We reinstalled the burden resistor across the CT and viola we cranked the generator right up to 570 kW with no issues. Problem solved! Thanks everyone! Now what's going to eat away at me is the electrical theory aspect of why with no ground...
I zoomed in on the vendors manual image and the resistor i saw hanging is definitely the burden resistor designed for the sensor. 200 ohm 10 watts it looks like it says just like I saw. Unfortunately i won't be able to have the resistor hooked back up and run the test again until the load bank...
Also good observation on the bond to ground on the secondary CT wiring. I was not able to verify if that existed in the field but next opportunity I will have them look for that
Those phone numbers arent to that company anymore and I could not find who took over this product online but good thought i might be abke to pursue this further. Also 350 mcm or kcmil sound right I originally thought 500 off the top of my head but that puc says 350 amd there's two per phase. We...
Thats so funny you mention the burden resistor because I had notices a 200 ohm cement /ceramic looking resistor terminated on ine end if the CT secondary terminals but the other end of the resistor dangling in the air. I am not sure how it got that way or if that is the burden resistor because...
Does anyone know anything about capacitive coupling between an ungrounded generator and ground possibly causing nuisance trips on the ground fault relay?
The generator neutral is bolted to an isolated piece of bus and has a reaistance if 4200 megaohms to ground. The load bank circuitry read 480 and the generator panel meter read 480 v but we did not take any readings with a volt meter on all the combinations u mentioned.
The output of the 1000 amp breaker has 2) 500 mcm cables per phase going back to the vendors load bank trailer. These cables are not moving anywhere lol. The current sensor is built into place besdes the removable front section. This or determ the secondary CT leads from the the Hi-Z ground...
This current sensor system on three phases sees the sum of the current in vs current out. If there is no ground the vector sum is zero regardless of phase load imbalance. But keep in mind the CR was only installed correctly half the the time and result was always the same.
The voltage is steady at 480 Vac and I was told the current is at around 300 to 400 amps.
The output breaker trips at 1000 amps and the GF relay dial is set at 200 amps of ground fault current after a 6 cycle delay at 60 hertz. Theres no way its producing an actual 200 amp fault to ground it...
The vendor would not let us remove the loan bank trailer from ground for procedural and safety reasons and I don't blame him.
Its not really am imbalance the ct is sensing ao i phrases that wrong. In theory A and B could draw 5 amps and C draws 10 amps but if there's no ground current all the A...
We have been testing a Cummins VTA-1710-G2 Diesel Generator 1800 RPM 480 Vac 671 kW with an Avtron K580 load bank that is hooked up to our three 480 Vac output cables and one cable to our facility ground. The generator output breaker keeps tripping when the load is around 350 kW. The test...