I'm looking at a project where the customer wants to add a new LV 2000kW 480V roll-up generator provision to feed onto their existing 13.8kV system during emergency conditions.
The attached sketch in black represents the existing 13.8kV system which includes the M-T-M 13.8kV switchgear at the bottom of the drawing in their main electrical room. The 27kV switch at top of sketch and the 13.8kV breakers in middle of sketch are located in utility entrance area. I'm not 100% clear at the moment where the line of demarcation is with the utility in this area.
In order to provide the provision for the new roll-up generator I'm looking at two options depicted with RED and BLUE on the sketch and was curious to hear from others what the best option here was.
The option depicted in RED shows the new roll-up generator provision going through a step up transformer and tied into the existing 13.8kV line that is running between the substation yard and the main electrical room. This would involve the addition of a 13.8kV rated switch to switch between utility and generator as shown. The one potential issue I see here is that with the gen feeding into the same main breaker in the downstream switchgear as the utility the existing 1200:5 CT's may be too large for the 100A generator current that will feed into this breaker. Are there any considerations here depending on where the utility SE point is (If these are considered SE feeders or not?)
The other option depicted in Blue includes adding a new breaker structure to the existing switchgear lineup and feeding it from the new roll-up generator transformer. The downside here is that there would be a pretty decent cable run (500') to get from the step up transformer to the new breaker structure. In addition it adds the complexity of how to add new structure to existing lineup (cable vs bus connection). This new structure could have CT's sized for generator load.
Is option 2 considered the preferred option here?
The attached sketch in black represents the existing 13.8kV system which includes the M-T-M 13.8kV switchgear at the bottom of the drawing in their main electrical room. The 27kV switch at top of sketch and the 13.8kV breakers in middle of sketch are located in utility entrance area. I'm not 100% clear at the moment where the line of demarcation is with the utility in this area.
In order to provide the provision for the new roll-up generator I'm looking at two options depicted with RED and BLUE on the sketch and was curious to hear from others what the best option here was.
The option depicted in RED shows the new roll-up generator provision going through a step up transformer and tied into the existing 13.8kV line that is running between the substation yard and the main electrical room. This would involve the addition of a 13.8kV rated switch to switch between utility and generator as shown. The one potential issue I see here is that with the gen feeding into the same main breaker in the downstream switchgear as the utility the existing 1200:5 CT's may be too large for the 100A generator current that will feed into this breaker. Are there any considerations here depending on where the utility SE point is (If these are considered SE feeders or not?)
The other option depicted in Blue includes adding a new breaker structure to the existing switchgear lineup and feeding it from the new roll-up generator transformer. The downside here is that there would be a pretty decent cable run (500') to get from the step up transformer to the new breaker structure. In addition it adds the complexity of how to add new structure to existing lineup (cable vs bus connection). This new structure could have CT's sized for generator load.
Is option 2 considered the preferred option here?
