Sean.Day72
Member
- Location
- Florida
I read around on here but couldn't find something specific for this situation.
I have two 2500KVA transformers. One transformer is normal utility power, the other transformer is Fed From a large generator facility for emergency power. I also have two pieces of Switch Gear. One switch gear has a Main 4000A breaker and is fed from the Normal Utility transformer. The other switch gear has a 3000A main breaker is fed from the emergency transformer. The Gears are located in separate rooms. The Normal Gear has a 3000A breaker which feeds a 3000A tie breaker on the emergency gear w/ 8 Sets using 4#400, #400G cables. The Tie breaker is normally closed to feed the loads on the emergency gear from normal utility power. If power goes out the tie breaker opens, main breaker on emergency gear closes and emergency loads are fed from generator. Note the loads on emergency gear are things like elevators, security systems, etc so they operate during normal and emergency situations. Also there will be neutral loads (4 wire system).The ground buses in each gear are connected with a cables.
Question the system Ground-Neutral bonding jumper should be at the tie breaker in the emergency gear correct? Any system bonding should be "ahead" of the ground fault sensors if I'm understanding correctly. I'm intending to use 4-pole breakers with an internal CT on the neutral. There should also be a CTs on the Ground-Neutral bonding jumper. These connect to each breakers trip unit to compare ground to neutral currents correct? In this case that would be 4 breakers. Any special considerations when setting up the trip units as to not mess up breaker coordination?
I using "single point grounding scheme" since the sources are not parallel. I can draw up a basic one line if my explanation is not clear.
I have two 2500KVA transformers. One transformer is normal utility power, the other transformer is Fed From a large generator facility for emergency power. I also have two pieces of Switch Gear. One switch gear has a Main 4000A breaker and is fed from the Normal Utility transformer. The other switch gear has a 3000A main breaker is fed from the emergency transformer. The Gears are located in separate rooms. The Normal Gear has a 3000A breaker which feeds a 3000A tie breaker on the emergency gear w/ 8 Sets using 4#400, #400G cables. The Tie breaker is normally closed to feed the loads on the emergency gear from normal utility power. If power goes out the tie breaker opens, main breaker on emergency gear closes and emergency loads are fed from generator. Note the loads on emergency gear are things like elevators, security systems, etc so they operate during normal and emergency situations. Also there will be neutral loads (4 wire system).The ground buses in each gear are connected with a cables.
Question the system Ground-Neutral bonding jumper should be at the tie breaker in the emergency gear correct? Any system bonding should be "ahead" of the ground fault sensors if I'm understanding correctly. I'm intending to use 4-pole breakers with an internal CT on the neutral. There should also be a CTs on the Ground-Neutral bonding jumper. These connect to each breakers trip unit to compare ground to neutral currents correct? In this case that would be 4 breakers. Any special considerations when setting up the trip units as to not mess up breaker coordination?
I using "single point grounding scheme" since the sources are not parallel. I can draw up a basic one line if my explanation is not clear.