Motor Relay P.u.

Hi all,
What is meant by the motor relay was tested at 1.0 p.u. of FLA?
and what is greater 5.5 p.u. or 1.0 p.u?

Thanks

Overloaded Cab Banks

Dear all,
I have capacitor banks overloaded morethan 130% (as per IEC). What action shall I take?How to rectify?

Kindest regards,

Harmonics And Motors

Hi all,
How to mathematically explain the effect of harmonics on motors? It is said that harmonics will cause motor overheat, But since we have inductance (windings) whose reactance is 2(pi)(f)(L)...which means that more frequency, more reacance, less currant flowing, less losses, less overheat.

Any help?

Transformer Tripped

Guys,
I have a transformer tripped due to pressure relief valve.
Can somebody tell me what are the possible causes and solutions??

Thanks

Unbalnce Load Protection

Hi
Can someone explain me what is the negative phase sequence current?
What is its effect on motors?
How is it measured?

I am asking this because I have 1700kW, 315A motor protected by REF542+ tripped on spurious Earth fault and after studying the current trend it appeared that the current when the motor tripped was 270A(<315A). I suspect that the motor is tripped due to Unbalance Load protection which evaluates the measured amount of negative phase sequence current at fundamental frequency.

Knowing that the settings are:

1. Earth Fault Protection : 0.2In, 0.1s
2. Unbalance Load Protection: 0.09In,

Can somebody help??


Thanks