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I have a camp supplied with 4x 500 kVA generators. Supplying mostly single phase loads, lights, aircon tv's washing machines, dryers. There is also a kitchen that has several 3 phase loads.
During the day on low load, around 70 amps p/phase generator the unit controllers report the current correctly. When the workers return to camp around 530 and switch on the aircons, tvs, etc. The load requires, at 200amps p/phase (from fluke).
The problem is at around 530 the reported current starts dropping to zero. Without the current the generators cannot load share.
The layout is, each generator has a 4 pole syncro breaker on to a main bus. Each generator is connected to earth at the star point and there is an addition MEN on the bus. This earth is wired via PE cable back to the frame of each generator and the star point. The controllers measure current in each phase via CTs ( 3 phases not neutral) the control is wired directly to the S1 terminal of each CT and common return to the controller. The common return is earthed.
I have measure current returning on the PE cable from the( main bus to the generator) it is in the order of 15 amps for each generator. When the neutral is reading 50 amps.
I am wondering if the earth current or the single phase loads could somehow be cancelling out the current summation going to the controllers. As I said earlier low loads it fine, but on high loads, zero current is report. On occasion at high loads one or two phase would report roughly 1/5 of the load.
Has anyone experienced this before
ps the CT and Controllers are rated at 1000/5
During the day on low load, around 70 amps p/phase generator the unit controllers report the current correctly. When the workers return to camp around 530 and switch on the aircons, tvs, etc. The load requires, at 200amps p/phase (from fluke).
The problem is at around 530 the reported current starts dropping to zero. Without the current the generators cannot load share.
The layout is, each generator has a 4 pole syncro breaker on to a main bus. Each generator is connected to earth at the star point and there is an addition MEN on the bus. This earth is wired via PE cable back to the frame of each generator and the star point. The controllers measure current in each phase via CTs ( 3 phases not neutral) the control is wired directly to the S1 terminal of each CT and common return to the controller. The common return is earthed.
I have measure current returning on the PE cable from the( main bus to the generator) it is in the order of 15 amps for each generator. When the neutral is reading 50 amps.
I am wondering if the earth current or the single phase loads could somehow be cancelling out the current summation going to the controllers. As I said earlier low loads it fine, but on high loads, zero current is report. On occasion at high loads one or two phase would report roughly 1/5 of the load.
Has anyone experienced this before
ps the CT and Controllers are rated at 1000/5