[pillay]

@doc70 said:
I have a 13800V to 600V 2MVA step-down transformer.

I need to megger test this unit, I have a megger good for 5KV and also a hi-pot DC tester (Megger brand).

I am unclear of how to make the physical connections between the transformer and the testers.

make sure the transformer is not connected to any thing like the potential transformer,than carry out

[1] usual insulation test between the frame and the connections terminations of the ht side.

[2] test between frame and the lv side terminations.

[3] test between ht terminations and LV terminations.

[4] test between phases at HT side

[5] test between phases at LV side.

[6]

[pillay]

thanks for the reassuarance,but the protection unit ABB  SPAJ was inter changed between the sender and receiving end but it still tripped at the sender end , furthermore later tests by calibration guys found both units to be good.I still pray its just the protection systems pc board.

[pillay]

It looks like ther is a leak most probably above the oil level, thas why you cannot see any sign of leakage.

[pillay]

sinnadurai sripadmanaban said:

1)Should we disconnect capacitor bank when powered by a generator?.

2)Can somebody give ratings of capacitors for starting(reducing starting current) induction motors for various sizes of motors(hp/rpm)?.

3)Can somebody give ratings of capacitors for pfc of individual motors of different hp/rpm

Thanks

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sinnadurai sripadmanaban said:

1)Should we disconnect capacitor bank when powered by a generator?.

2)Can somebody give ratings of capacitors for starting(reducing starting current) induction motors for various sizes of motors(hp/rpm)?.

3)Can somebody give ratings of capacitors for pfc of individual motors of different hp/rpm

Thanks

1) Capacitor banks are connected to correct the PF in the system,if the pf is low, than for the same load the ampere would be higher.If your load is always below fulload or tripping treshold than its ok you may disconnect  the pf bank.

2) Caps are not used for reducing starting current.

3) Ratings of capacitors for pf correction can only be determined by knowing your existing pf and to what pf you want to improve to.

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Juan Carlos said:

By the rules in Brazil, users supplied at voltages greater that 2.3 kV (group A) must have their PF verified by the utility in a mandatory and permanent way (art. 34, reg. 456/00). Users supplied at voltage lower than 2,3 kV (group B) can measure their PF in a facultative way. If that PF is lower than 0.92 (inductive or capacitive), reactive energy consumption and demand are mesure and charges apply (Art. 49, reg. 456/00). Furthermore, according to art. 68, reg. 456, users from group B can be charged by their reactive energy and demand, if their PF is lower than 0,92 during a minimum period of 7 days. From my point of view, if utilities adopt electronic meters to also register the PF of residential users, there are no regulation that don't allow them to charge us by the reactive energy. So, the end is near… Are you agree?

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[pillay]

A simple fluorescent tube light wastes about 20% of energy in the choke. Of course compared with an incandescent bulb it is more efficient but thinking of all the flu tubes around with chokes.

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