For monitoring the current consumption of electrical consumers, for industrial and railway applications, the relays measure the arithmetic mean of the rectified measuring current, whereby the devices are calibrated for sinusoidal alternating currents in effective value, both the response value and the release value can be set on the devices via the hysteresis, the devices work as overcurrent relays, they can also be used as undercurrent relays, the dependency of the hysteresis on the setting value must be observed
