A recent test port fault indicator helps workers quickly locate faulted circuits in underground distribution systems. Its design incorporates advanced circuit logic and monitoring system protection to prevent the indicator from tripping, unless an over-current condition is followed by a loss of system voltage.
The Fisher Pierce TPM Series Test Point Mounted Fault Indicator mounts directly to any IEEE 386 capacitive test point and consists of a solid-state current sensor connected to a faulted-circuit display, providing a clear visual means for locating faulted cables and equipment.
The fault indicators operate when a faulted circuit produces an associated magnetic field, which closes a reed switch in the indicator, resulting in a tripped display. Trip response occurs within one millisecond, allowing the fault indicator to coordinate properly with all types of circuit-protection schemes, including current-limiting fuses. Trip and reset operations are automatic. For versatility, the same indicator may be used for 5kV through 35kV applications.
In addition to the commonplace flag-display configuration, the units are available with LED and fiber-optic displays.
Thomas & Betts Corp.