Tripping of Compressor on energizing transformer on same common bus
Tripping of Compressor on energizing transformer on same common bus
(OP)
We have a cotton weaving unit with 6 gas generators at 380V output. All 6 generators are connected to 6 step up transformers (connected star-delta i.e. output 11kV side is delta and no neutral is present!). Out of all 6 transformers is connected in parallel to a common 11kV busbar. From the busbar, an induction motor compressor (11kV, 3-phase, 50HZ, 1300kW, make: Cooper) is supplied. From the same busbar, a step down transformer of 2500kVA (11kV delta / 415V star) is connected for other loads of the factory. Now, whenever we energize this 2500kVA unit, the Cooper induction motor trips! This is problem of the factory from last 6 years (i just joined the factory and guys there say its a "built-in" problem. they wait for sometime, and after 2500kVA inrush dies away, they re-start the compressor... wierd).
Why does this happen. Is it because there is no neutral present (from the generators transformers upto load)? Will a zigzag transformer solve the issue?
Why does this happen. Is it because there is no neutral present (from the generators transformers upto load)? Will a zigzag transformer solve the issue?






RE: Tripping of Compressor on energizing transformer on same common bus
A first guess would be unbalanced voltages. The transformer will take a very high inrush current that will not be balanced, phase to phase. That coupled with the fairly high impedance of generators (compared to transformers) may cause enough voltage unbalance to cause a voltage trip.
Bill
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"Why not the best?"
Jimmy Carter
RE: Tripping of Compressor on energizing transformer on same common bus
Then, when the factory procured gas gensets, someone made a mistake to procure these star-delta transformers (delta on load side - 11kV), and then problem started occurring!
RE: Tripping of Compressor on energizing transformer on same common bus
We need more information, settings of protective relays.
Not bad and help us some disturbance recorder data from protective relays.
RE: Tripping of Compressor on energizing transformer on same common bus
what I understand that if you add a time switch and/or replace this undervoltage with a modern having time delay function could solve the problem.On other hand if if time switch is already there; try to increase the time delay and/or voltage settings.
As waross indicated the generators & transformers impednace could also be an issue; that is higher impednace mean higher volt drop when inrush currents flows through them.
More data regarding impednaces and relay settings is required.
musa UKPN
RE: Tripping of Compressor on energizing transformer on same common bus
RE: Tripping of Compressor on energizing transformer on same common bus
its news....