Ground Fault Location in Ungrounded Systems
Locating ground faults in an ungrounded system is simple with the right technology. The techniques are different
than locating ground faults in a grounded system. In a grounded system, locating faults is done via a multi-channel
Ground Fault Relay utilizing current transformers to pick up on leakage current for each individual circuit/load.
However, due to the nature of the ungrounded system where a first ground fault will not create leakage current, a
different technique must be employed.
Ground fault location in an ungrounded system can be done via a fixed installation, portable devices, or a combination of both.
A controlling device with a pulse generator is present upstream in the system. This device sends a low level artificial
signal into the faulted system. The signal will be impressed between the power wires and ground. Naturally, it will
follow the ground fault path into ground and return to the pulse generator. This signal can be traced with special
fixed current transformers or a special portable current probe. This method works while the system is still online,
and ground faults can be located down to the load causing the problem while all systems remain in operation.
Figure 1: A complete ground fault location system for ungrounded systems
The fixed installation is useful where 24/7 monitoring is required, as well as giving portable location a
head start as to which circuit is causing the problem. The system consists of the following:
- IRDH575 Ground Fault Detector and Controller; Detects ground faults in the system and supplies the pulse required for ground fault location.
- EDS460 or EDS490 Ground Fault Location Device; Monitors up to 12 separate circuits for the pulse to locate a ground fault in a subcircuit
- W Series Current Transformers; Connects to the EDS460/490 for monitoring each separate circuit.
The Bender EDS ground fault location system is an excellent tool for the maintenance personnel in a large facility with extensive wiring.
Faults will be located automatically during normal business operation. No shutdown required. No handheld tracing and/or accessing panels required.
The beauty of this system lies in its non invasive operation. The ungrounded system is only safe for its user as long as the occurring faults are
immediately traced down and eliminated. If that is not the case, then the second ground will follow sooner or later and short circuit the system.
The EDS3090 portable ground fault location series can be used as a completely standalone location system or used in tandem with installed units.
Pulse generation is done either by an installed IRDH575 or a portable pulse generator that can be connected up to the main system. The pulse is traced
via a hand-held clamp. The general process for this system is by starting at the point of pulse generation, and tracing the pulse down to the load
causing the ground fault with the clamp. Ground faults can be located quickly and easily, again while the system remains online and operational.
Using the EDS460 and EDS490 installed ground fault locators in tandem with the portable EDS3090 system gives technicians a head start as to where to begin clamping.