The Megger MGFL100 Battery Ground Fault Locator locates ground faults on ungrounded DC and AC systems, DC battery systems, and protected IT networks. The instrument alarms when the real fault is found, while automatically distinguishing between real fault current and reactive current drawn by stray system capacitance.

DC Ground Faults

The MGFL100 measures the ground fault resistance, system capacitance, real fault current, and reactive leakage current. The instrument also locates high impedance ground faults due to water ingress, as well as ground faults on systems with high leakage current. The MGFL100 makes locating the ground fault fast and easy by alarming when the circuit with a real ground fault is located. No complicated tuning out of noise or capacitance is required. Users can easily trace the fault with the lightweight transmitter and receiver. Users can also set both password protected voltage and current limits to ensure that they never put too much current into their system.

AC Ground Faults

Specially protected IT networks, such as those found in hospitals, are designed in such a way that any contact with a voltage carrying line is harmless. In the event of a short to earth, protection reduces current flow to zero. Important control, signal, and supply systems, such as those for railway installations, power plants, or other industrial facilities, are designed to be potential-free and are monitored by earth fault indicators in order to ensure safe and uninterrupted operation. Short-to-ground faults in IT networks, control lines or, for example, signal lines in railways are referred to as earth faults.

While a single earth fault will not disrupt the service, a second earth fault carries a high risk of partial or complete installation breakdown. For this reason, any earth fault must be located and repaired as fast as possible. The MGFL100 allows tracing of these faults by directly coupling to the line. This can be done either off-line or on-line by using a coupling filter.

An Array of Features

The MGFL100 transmitter measures the total fault resistance and leakage capacitance before users start tracing. This allows users to not only see the actual resistive value of the fault, but also determine if there will be phantom shorts due to leakage current. The receiver directly measures the resistive fault current and the leakage current. The MGFL100 will provide a visual, as well as an audible alarm when a real ground fault is located. It will not alarm on circuits that draw leakage current due to capacitance. Users will be easily able to see which circuits have the real resistive fault. This will prevent users from chasing phantoms. There is no tuning required, and the measurements are done automatically.

The transmitter leads are fused at the connectors for safety. ARC flash is always a concern when connecting to a battery string. The battery string is a DC system. There is no zero crossing to dampen an ARC flash on a DC system. The fused leads will open to prevent a hazard from arising. The fused leads will keep a mistake from becoming a disaster.

Users can set both voltage and current limits. This ensures that neither the voltage nor the current will exceed circuit limits. These limits are password protected, so they cannot be accidentally changed. This ensures there is no accidental breaker tripping.

The transmitter can be powered off of AC or battery power. This allows for fault locating in any location. The MGFL100 will also identify the side of the string with the ground fault so there is no need to use a DMM. The 5.12 Hz AC signal allows for tracing of the fault, which is ideal for operation on noisy systems. The AC output will not trip DC breakers like a DC pulsed output can. The low frequency output allows for operation on low frequency 16.67 Hz systems.

Users can ultimately locate faults on both AC or DC systems. The MGFL100 will locate faults on ungrounded DC systems, including high resistance center grounds, or IT grounded AC systems with the use of an optional IT isolation filter (not included). The receiver will also trace AC line current on any type of system.