804B. I'm not able to get voltage to 480. Help.

We bought a 804B last year to run a irrigation pivot, we needed to to run 480V it was doing 440v I replaced the voltage control rheostat this spring now it's only giving me 360 to 380 volts. Any recommendations? I am going to order a new voltage control rheostat are there any suggestions on where to get a good one?

If you look at your Generator carefully then you will discover a nameplate like this one here:



the nameplate indicates that this particular model is rated for either
120/208 or 240/416

you can kiss the ground you are walking on that it ever got up to 440 in the first place.

To get to to 480 you will need to get a three phase step up transformer

+1, its not a 480v generator. Its 416v.

Yeah I have the same plate I guess now I'm just curious as to why it has a plate showing it can do 480. Or am I understanding it wrong?

Harris101Ranch said:

Yeah I have the same plate I guess now I'm just curious as to why it has a plate showing it can do 480. Or am I understanding it wrong?

Click to expand...

The voltage adjust rate is the range the voltage adjust rheostat can adjust the output voltage in general.

Its 395 VAC on the low side and 480 VAC on top side. Both are the absolute maximum and minimum ratings of adjustable range.

When the A1 / A11 start to go bad, then the range indicated on name plate can no longer be achieved, resulting in preventive maintenance.

The rating is 416 VAC or 208 VAC, that is what the Generator Head is designed and built for.

Operating the Generator at any other Voltage then 208 VAC or 416 VAC can cause problems and premature equipment failure.

The A1 / A11 is the number one casualty, then the exciter assembly and its Diodes

Its up to the operator to make the judgement call and carry the responsibility when operating at extreme limits.

Because of the age and the aging of the components in the A1 / A11, most units won't go higher then ~ 440 to 450 VAC