The increasing demands for electricity and the prohibitive cost of installing transmission lines (along remote, inaccessible or uneconomical routes) means stand-alone and emergency generators are being installed in challenging locations.
To support this requirement Cressall introduced their modular range of neutral earthing resistors with standard cabinet designs to house 1, 2, 3, 6 and 9 contactors, for generators from 3.3 to 13.8kV system voltages.
It is important to remember that with medium-voltage power generating schemes that have multiple diesel generating sets, it is necessary to ensure that only one of the neutrals of the running generating sets is earthed at any time (this is to avoid the possibility of currents circulating through multiple connected neutrals).
This means costs and delivery times are considerably reduced while quality and reliability are improved.
Cressall can supply NERs fitted with fixed pattern vacuum contactors – these can be offered for operation on auxiliary voltages up to 220V AC or DC and with options for remote or local and remote control.
Neutral Earthing Resistors (NERs) can be fitted with manual or motorised off-load isolators, either singly or in interlocked pairs if the purpose is to switch between resistance earthing and solid earthing.