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Relays offer enhanced resistance to inverter noise

27 June, 2013

Omron has developed a range of power supply monitoring relays designed to protect against problems such as motor burnouts and other malfunctions that can result from power supply issues.

The K8AK / K8DS series relays can detect voltage or current errors, phase losses, and phase sequence errors. They offer enhanced resistance to inverter noise compared to Omron’s previous models. They suppress heating in the relays themselves resulting from inverter noise, and will monitor power supply troubles even if a noise filter is not installed in a device or machine.

The relays are designed, in particular, to cater for the expansion of manufacturing activities in emerging countries which can experience problems such as:

•  machines and devices malfunctioning as a result of voltage fluctuations;

•   motor rotation errors caused by incorrect wiring of power cables or motor burnouts caused by loose wiring; and

•  over-heating and other problems resulting from inverters that are not fitted with filters.

The relays (shown above) can detect problems such as:

•  over- and under-currents, and over- and under-voltages;

•  phase losses (where voltage is not supplied to one or more phases because of disconnected power lines, loose terminals, or contact failures);

•  phase-sequence problems  (which can result, for example, in motors rotating backwards); and

•  voltage asymmetries  (where the voltages of different phases  are different because of phase losses or other causes).

The relays are available in various single- and three-phase versions for currents up to 200A and voltages up to 600V. The 17.5 and 22.5mm-wide Din-rail mounting devices are said to save space in control panels.

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