ggreenx
Member
- Location
- I live in Chula Vista, California
I have a project in which I need to provide a link between a 480 volt PV inverter, with a wye output, to a 480 volt utility service with a wye service (with loads connected on it). Due to the length of the proposed 480 volt feeder, we are going to stepup to 12kV, then stepdown back to 480 volt. I have a distribution manual that suggests I use a 480 volt delta to 12kV wye transformer for stepdown from the 480 volt inverter, and a 12kV wye to 480 volt delta stepup transfromer to get back to 480 volt and connect to the utility service bus. The manual suggests that delta wye stepup and wye delta stepdown is the best configuration.
In this scenario, I believe the 480 volt delta sides of the transformers are fine since the inverter and the utility service are both already grounded (neutral bonded to ground), and that each of the 12kV wye sides of the transformers would need to be grounded (neutral bonded to ground).
This proposed design seems to be fine with me based on what I know. Does anyone take exception to this proposed design or have any comments regarding this? Am I missing anything?
I had another engineer suggest to me that the transformers could each be delta delta but I am thinking that I need to have a ground reference for the 12kV feeder. I have also heard that it is always best to use delta wye transformers...something about zero sequence impedance.
In this scenario, I believe the 480 volt delta sides of the transformers are fine since the inverter and the utility service are both already grounded (neutral bonded to ground), and that each of the 12kV wye sides of the transformers would need to be grounded (neutral bonded to ground).
This proposed design seems to be fine with me based on what I know. Does anyone take exception to this proposed design or have any comments regarding this? Am I missing anything?
I had another engineer suggest to me that the transformers could each be delta delta but I am thinking that I need to have a ground reference for the 12kV feeder. I have also heard that it is always best to use delta wye transformers...something about zero sequence impedance.