Tuesday, July 31, 2012

Neutral grounding transformers

Neutral grounding transformers

When a neutral grounding reactor or ground-fault neutralizer is required in a three-phase system and no suitable neutral is available, a neutral must be provided by using a neutral grounding transformer. Neutral grounding transformers are available for continuous operation or short-time operation.

The zero impedance is normally low. The standard vector groups are zigzag or wye/delta. Some other vector groups are also possible. Neutral grounding transformers can be built by Siemens in all common power ratings. Normally, the neutral grounding transformers are built in oil-immersed design, however, they can also be built in cast-resin design.

A grounding transformer is intended primarily to provide a neutral point for grounding purposes. It may be provided with a delta winding in which resistors or reactors are connected.

When a ground fault occurs downstream of the grounding transformer, ground fault current flows through the fault
and back through ground to the grounding transformer. The loading resistor limits the current flow in the secondary winding, which in turn limits the flow of the ground fault current back into the system through the primary of the grounding transformer.

 33kv generator neutral grounding resistor cabinet

 10KV Grounding Transformer

 240V Grounding Transformer with Stainless
steel resistor banks and Type 3R powder coat
painted enclosure

 Neutral grounding transformers Back View

 Neutral grounding transformers Front View

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