I have three protection CT's (1 in each phase) in the delta loop of a star-delta starter. The original installation had the CT secondary's (s2)connected together and grounded, and the s1's are connected to a motor protection relay (MPR)
However the protection relay manufacturer's generic data...
Is there any formulae available, from which you can deduce whether direct online starting of a motor will dip the mains voltage to an unnaceptable level, given the 3 phase fault current level at the motor control center.
i.e If I have a 3 phase fault level of 25kA at 415 volts at the MCC, would...
I have a 2 element kwh meter which is reading only 20% of the expected calculated kwh value. It is connected to a 3.3 kv system via two residually connected ct's, and two vt's with a common secondary ground. I have a power analyser meter on which I have measured the input to the upper and lower...
I have a 2 element kwh meter connected to a delta balanced 3 phase system. It utilises 2 ct's (residually connected to red, and blue phases) and 2 vt's(connected with a common secondary earth). The meter is reading only 20% of the expected calculated kwh.
I suspect that one or both of the ct's...
Can anyone help with the american cable core colouring system. In a single phase system I have black, white and green. Is white the conventional live core ?
In a three phase and earth (delta) system I have red, white, black, (and green). What is the conventional rotation ?
e.g. in U.K it is red...
Is it true to say that given the 3 phase short circuit fault current at a certain point in a system, that a fault between two phases only will produce 0.865 times the 3 phase current value in those two phases ?
