CKM-10 phase sequence sensor is used to protect devices powered from a three-phase network (e.g. motors) against damages as a result of the loss of phase voltage, phase voltage asymmetry or incorrect phase sequence. The value of the asymmetry threshold can be set by the user with a potentiometer. The sensor protects also against a symmetrical drop of voltage switching the relay off if the voltage on any of the phases drops below 150 V (regardless of asymmetry level). The device can be supplied from any phase what causes that the presence of voltage on one phase is sufficient to ensure full functionality. Adjustable shutdown delay and voltage hysteresis causes that the sensor is resistant to short-term voltage fluctuations.