Advanced Energy 50 kw grid tied inverter 480v 3 phase, four wire, wye connection

[Neal30]

We are connecting an advanced energy 50 kw inverter to the utility. The commercial site has a
480V 3 phase 3 wire delta pole mounted transformer configuration. The inverter has a
480V 3 phase, four wire, wye output. Would we be able to connect into the utilities configuration as is, or would we need to use an isolation transformer?

http://solarenergy.advanced-energy.com/en/PVP35kW_50kW.html

Inverter spec sheet above.

I would appreciate any reference material you could recommend to verify either conclusion if at
all possible.

Thanks

 

[jaggedben]

If a neutral is required for the inverter to operate correctly and safely, then you'll need an isolation transformer.

My advice would be to contact Advanced Energy and ask them directly if a neutral connection is required and why. Get it from the horses mouth.

 

[Neal30]

Isolation Transformer Required.

Isolation Transformer Required.

We installed the transformer. New question: The same inverter, different point of connection. 3 phase 4 wire wye panel. Rated at 250 amps. Inverter needs 80 amp 3 pole breaker. Do I need to divide or multiply by 1.732 somewhere?

250*1.2=300
300-250=50 amp breaker
50*1.732=86.6?

If this is wrong use of this calc, then a fused disco and a tap before the panel

Ideas welcome.

 

[ggunn]

We installed the transformer. New question: The same inverter, different point of connection. 3 phase 4 wire wye panel. Rated at 250 amps. Inverter needs 80 amp 3 pole breaker. Do I need to divide or multiply by 1.732 somewhere?

250*1.2=300
300-250=50 amp breaker
50*1.732=86.6?

If this is wrong use of this calc, then a fused disco and a tap before the panel

Ideas welcome.

At 480V, that inverter's max current is 61A. 61A * 1.25 = 76.25A, 80A breaker is correct.

By the 120% rule, I don't think you can put it into a 250A panel. No sqrt3 involved.

 

[SolarPro]

Right. In order to meet the 120% rule with regards to the busbar, you would need to be able to downsize the main breaker to 200 A. (200 A + 80 A is less than 300 A, which is 125% or 250 A.)