FENTON, MO. CR Magnetics Inc. has geared its CR7310 series of ground-fault sensors to provide overall equipment protection in a range of applications, such as monitoring motor-ground faults in submerged pumps and sensing early failures of heater elements.
Rated for UL 1053-Class 1, the CR7310 components sense ground-fault currents in single-phase and multiple-phase electrical systems, from 100 amps ac to as low as 10 mA. Supply voltages are 120 or 240 Vac.
The sensors operate by routing the current-carrying wires through the opening of the current sensor. When ground current reaches the level set by the trip-point adjustment, the electromechanical relay is energized. It illuminates the tripped LED and provides an output signal. A precision voltage-reference circuit is said to ensure a highly repeatable trip point.
The series features a variety of relay or solid-state output options, including an electromechanical relay, optoisolated npn transistor and optoisolated triac. Internal or remote current sensors fit specific location needs.
A calibrated dial option makes it possible to adjust the LED trip-status indicator for instant viewing of the current trip point. An adjustable trip point can monitor different current levels. Variable time delays inhibit activation during motor startup, and electronic isolation between circuits protects instrumentation from high voltage.
The devices' case size measures 2.5 x 3.5 x 2.125 inches for the internal CT units and 2.5 x 3.5 x 1.55 inches for the external CT units. List price is around $130. Standard styles are in stock.
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EETInfo No. 615