The hand-held 

Rapid DC & AC FAULT LOCATION with the EUMAC  GH-01 "Ground Hog"

Cost effective, non-intrusive ground fault location is a reality with the EUMAC model GH-01 Ground Hog.  The GH-01 is a patented (U.S. patent#4,884034) battery operated, hand-held instrument for safe efficient location of faults.  This instrument rapidly locates ground faults on ungrounded 48 to 250v DC and AC systems.  Ideal for detecting faults in systems used for control, protection, and vital auxiliary equipment in power plants, transmission system substations and industrial processes.  The GH-01 allows you to locate ground faults without the need to open a breaker thereby disrupting critical loads.  The "Ground Hog" is easy to use and can locate even high impedance ground faults on noisy battery systems with significant capacitance to ground.

How Does It Work?

The GH-01 Ground Hog applies a low amplitude short duration current pulse from the (positive or negative) leg of the dc circuit under test (CUT) to ground.  If a path through ground back to the ungrounded opposite polarity exists, it is detected by a clamp-on current transformer (CT) which drives a ground current pulse detection circuit in the GH-01.

An electrician searching for dc ground makes a test connection between the positive source lead and ground with the GH-01 and applies the test signal.  The clamp-on CT ground current pulse detector is moved from branch to branch until an indication of a ground current pulse is received.  If no ground is detected with the test circuit connected positive leg to ground, the test leads are connected with the negative leg to ground (in practice, one need only test the leg with the lower voltage to ground).  The clamp-on CT ground current sensor is again connected around each branch circuit under test until the fault is located. Click here for "Ground Hog" technical specifications.

Can the GH-01 Cause Operation of a Relay With a Grounded Coil?

The Ground Hog uses a low amplitude short duration current pulse under the control of the user.  Worst case current magnitude for a 130 vdc system is 260 milliamperes for a user selected time duration of 1 to 12 milliseconds.  This is not sufficient duration to pickup any sensitive relays we have tested.

What About Noise, System Capacitance and Inductance?

Real world dc ground fault location requires that the GH-01 is equipped to handle these situations.  A dc system typically has superimposed signals riding on its nominal output from a few hundred Hertz to several megaHertz. The GH-01 input signal conditioning contains filtering to reject these spurious signals.  In addition, a sensitivity potentiometer on the GH-01 front panel nulls out any remaining noise to establish the "noise floor" for the circuit under test.  Capacitive effects to ground and series inductance are accounted for by utilizing a variable width current pulse.  By producing both short and long current pulses, the GH-01 is able to differentiate between system capacitance and an actual fault which may have both an inductive and a resistive component.  Utilities using the GH-01 have found high impedance faults that did not indicate on their less sensitive ground detection alarm systems.

What Ground Hog Users Say:

A major U.S. utility estimates saving $600,000 a year in locating grounds on critical systems with 5 GH-01's at its 3 nuclear units.

"We are very happy with the Ground Hog.  We found 30K ohm grounds on our 130vdc systems easily.  No other fault locator we have tried has been able to do this."

"The fact that we don't have to open breakers has paid for the GH-01 in one use on critical systems."

You may contact any of the following regarding GH-01 performance:

Key Benefits:

Accessories Supplied:

Optional Accessories:

Warranty and Support:

One year parts and labor.  Unlimited phone support on applications and troubleshooting.

Pricing

EUMAC Inc. accepts Visa and Mastercard.  Please contact us at 602-942-9168 for credit card orders.  Your credit card will be billed after equipment ships.

Prices are listed in U.S. Dollars.

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Copyright ©  2000 Eumac Inc.
Last modified: November 08, 2005