Phase-missing relays actuate control systems in motor protection against the harmful effects of phase failure and / or phase asymmetry. The sensitivity of the degree of asymmetry between is adjustable via an adjustment knob on its front knob.
They have switch electrical contacts (11, 12 and 14) controlled by their electronic circuits that open or close depending on their protection.
When the system is energized under all normal conditions, it closes contacts 11 and 14, opening from 11 to 12. Contact number 14 remains open if there is asymmetry between the system phases, if any of the phases are disconnected or dropped. from neutral.