Monitoring the Neutral Ground Transformer

Related Products:

EMMK-101, EMMK-102, EMMK-103, EMMC-104, EMMC-105, EMMC-106

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neutral ground transformer, NGT


Explains how to monitor the Neutral Ground Transformer conductor.

Monitoring the Neutral Ground Transformer

The Neutral Ground Transformer (NGT) conductor can be monitored in two ways: around the conduit that houses the conductor before it enters the NGT cubicle or around the conductor itself within the NGT cubicle. If the conductor from the WYE connection on the generator's neutral side is either a bus arrangement until it gets inside the NGT cubicle or a bar conductor with no conduit protecting it, the CT can be placed around the conductor itself. However, the conductor needs to be properly insulated for the rating of the generator itself.

When the CT is around the conduit and the conductor, it can detect signals from the antenna effect of the windings and the shielding effect of the generator frame. This is one of the more sensitive points to detect as well as the preferred location. If the CT is only around the conductor itself, you only get the antenna effect of the windings, so it is slightly less sensitive. If many units are being monitored, it may be the appropriate location to be able to compare similar units.

Comparing units with the CT around the conduit to units with the CT around the conductor only can be done but the sensitivity of the location should be accounted for.



A motor may not have any access to the neutral connection at all. So, in most cases this method is not used for motors.

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