Neutral Grounding Reactor?

[newschool]

I'm being required by the Utility to install a reactor on the neutral of my isolation transformer. The transformer is between the utility service and a grid interactive PV inverter. I have been doing some searching and I'm stumped. Every transformer manuf. I have called is turn offed by the size needed.

The inverter is a 100kw @ 480V. The transformer is a delta/wye 480-480 ( This is a whole story in its self). Utiliy requires Xo/X1 to be about 2 and X/R = >3 Xo being the transformer and X1 being the inverter. Assumed that the effective X1 impedance is 30%.

I have never dealt with designing or sizing reactors. Most companies I can find are in the large utility scale and scoff at my needs. Does anyone have a good supplier and/or maybe some incite on sizing a reactor.

Thanks

 

[templdl]

Did you try Olsun Electrics in Richmond, IL? Ask for an Air core reactor.

 

[newschool]

I'll give them a try

 

[ron]

Keep an air core reactor away from electronics. Lots of magnetics flying around because there is no iron core.

 

[kingpb]

It is one thing to be asked to do something, it is another to know why they want it. So, what is their intent for wanting the reactor?

Certainly they are not trying to have you provide resonant grounding. This is extremely difficult to achieve in general, and more so on a distribution system because it has to be tuned with the system capacitance.

Low impedance grounding is much more easily achieved and you can use a resistor or reactor. But it really depends on what do wan this for. :?

 

[jghrist]

The inverter is a 100kw @ 480V. The transformer is a delta/wye 480-480 ( This is a whole story in its self). Utiliy requires Xo/X1 to be about 2 and X/R = >3 Xo being the transformer and X1 being the inverter. Assumed that the effective X1 impedance is 30%.

X0 is the zero-sequence reactance, not the transformer reactance. X1 is the positive-sequence reactance, not the inverter reactance (does an inverter have a reactance?) You need to ask the utility if they mean these impedances to be of just the transformer and reactor or if they want the inverter impedance included in X1. I don't know where you would get the inverter impedance. Also ask if they mean for the X/R ratio to be X1/R1, X0/R1, or X1/R0. I also agree that you should ask for the reason for the reactor. If they want to limit ground fault current contribution from the wye side of the transformer, why not use resistor grounding? I assume that the grounded wye side of the transformer is the utility side.