The Megger BGL operates by injecting a 25 Hertz signal between the battery system and the ground. The resulting current is tracked by a clamp-on current probe, and the magnitude of the injected signal is only 3.5 volts and will not cause any interference with the operation of sensitive protective relays on the system.
The Ground-Fault Locator’s circuitry measures the 25 Hertz power dissipated in the grounding resistance and calculates the value of the grounding resistance from knowledge of the applied voltage, a method that allows the instrument to effectively eliminate the effects of charging current due to capacitance on the battery system or surge suppression capacitors that may be installed on the system.
The Megger BGL offers a wide dynamic range that allows simultaneous tracking of two or more ground faults that may be different in value. The injected signal is low enough in amplitude that it should not interfere with the operation of relays, even of the sensitive variety, under normal operation.
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