Recently i visited a process industry with uses around 650 KVA, 400V(line voltage), 50 Hz gas power engines to power their plant. What i found interesting in the switchgear room was that it utilizes a 3-phase, 3-wire system (in Y) in which the star point or node is grounded to earth via a resistor called NGR (Neutral Gnd Resistor). In addition there is no neutral bus bar. Technicians there say that neutral is not used here - its dead! and for getting 230V (phase voltage) they use transformers to step down from 400V to 220V so that 220V can be used for their control circuitry (control logic) for various MCC feeders.
I want to know what kind of a system is it where neutral is not used and what are the advantages of this kind of system with NGR and all that? Doesn't it require more maintenance now that there are so many transformers used just for 400V to 220V stepping down?
Thanx
I want to know what kind of a system is it where neutral is not used and what are the advantages of this kind of system with NGR and all that? Doesn't it require more maintenance now that there are so many transformers used just for 400V to 220V stepping down?
Thanx
