Current Relay Circuit
They activate at a fixed or adjustable current setting point.
Current relay circuit. A relay is a device by which electric current flowing in one circuit can open or close a second circuit i e. The operating circuit circuit 1 see the figure 1 is connected to a solenoid coil wound round iron core. Switch the current on or off in the second circuit. The current is set within certain limits according to rated currents of the motors.
If trip coil of breaker fails then tripping of breaker will not take place. Also known as power relays. The overcurrent relays are connected in series to the load circuit and the load current is passed through. Medium current relays these relays are rated for motors with 1 3 horsepower or 15 90 amps use them with industrial automation systems security and emergency lighting and small motors.
Working of the electromagnetic relay. When a pump is operated with a flooded suction and liquid completely covers its inlet the pump s motor will draw normal operating current. The overcurrent relays connected to the three phase conductors only control one relay in one phase alternating current circuits and the three phase conductors control the normally closed contact in the control circuit. Under normal condition the current through the relay coil is not sufficient enough to pull the plunger and close the circuit of breaker tripping coil.
Internal core current sensor relays internal core current sensor relays are designed to help monitor the current flow in a conductor. The current sensing relay in this water pump electrical circuit prevents the pump from running when the water level is too low.