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FAQ03219 of Measuring / Motor Protective Relays FAQ

FAQ No. FAQ03219

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What does "inverse-time operation" refer to in a Motor Relay?


This refers to a limiting motion caused by an overload factor. When a large current flows, the time until operation is shortened, and when a small current flows, the time until operation is lengthened.

The following figure shows inverse-time operation characteristics for the K2CM Motor Protective Relay.

Time Characteristics during Overload Operation
(Inverse-time Operation)

The motor itself will not burn immediately when an overcurrent is applied to it, and is generally able to withstand an overload that lasts approximately as long as the start-up time.
Inverse-time operation characteristics make it possible to prevent unnecessary operation stops by using the inrush current at start-up to trip the motor or stopping the motor when an overload condition extends for a short time.

Applicable models: K2CM, SE Motor Protective Relay

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