Fault indicator

A fault indicator is a device which provides visual indication of an electrical fault. They are used in electric power distribution networks as a means of automatically detecting and identifying faults.

Basic principles

During an electrical fault on a grounded system, additional current flows through a conductor, which is picked up by the fault indicator causing a state change on the target flag, LED, or remote indication device. Ground fault indicators for ungrounded systems sense the vector sum of the current and look for an imbalance indicating a fault on one or more of the three phases.

Types

Overhead

Overhead indicators are used to visualize the occurrence of an electrical fault on an overhead electrical system.

Underground

Underground indicators are used to visualize the occurrence of an electrical fault on an underground electrical system. Often these devices are located in an underground vault. Some vendors provided a wireless interface to eliminate the need of entering the underground vault in order to check the status of the indicators.

History

The first fault indicators came onto the market from Horstmann (Germany) in 1946. The E.O. Schweitzer Company introduced a product in the U.S.A in 1948. The first fault indicators were manual reset devices. Later fault indicators automatically reset on system restoration or after a set period of time. More recent fault indicators communicate their status (tripped or reset) via cell signal or radio to a central station, handheld device, or pole-mounted receiver.

See also

* Power transmission
* Polyphase system
* Electricity distribution
* Overhead powerline
* Power outage
* Three-phase electric power

References

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External links

* [http://www.eosmfg.com/index.html "SEL LINAM fault indicators"]
* [http://www.powerdeliveryproducts.com "Power Delivery Products fault indicators"]
* [http://www.cooperpower.com/Products/Components/Faulted/ "Cooper Power fault indicators"]