Relay
Relay voltages are used in small units up to 3/4 of HP. They consist of a coil whose ends are connected in series to the main winding of the motor, so the entire supply voltage of the main winding passes through the relay coil, so the magnetic field developed in the relay coil is proportional to the intensity developed in main winding contacts. Voltage relay contacts are always open only when the motor starts up to power the auxiliary.The contact closure is accomplished by the magnetic field developed in the relay coil at start-up to exert the torque and the inertia power from the stationary position. The high value of the starting voltage creates a strong magnetic field on the relay coil to draw the contacts of the relay and to connect the start winding circuit to the circuit. However, with the increase of the operating revolutions and after the inertia and the first torque resistance have been destroyed, the intensity and the capacity of the magnetic field of the coil, which can no longer hold the closed contacts, falls.
So the contacts open and set off the auxiliary winding. The relay contacts can be opened in two ways: a) the weight of the contacts themselves (b) by means of a spring The relay of the first category must always be placed in a position specified by the manufacturer. The upper part of this relay is marked with the word "TOP" or "UP" or has an arc showing the upper part of the relay of this type.
Relay voltages are used in small units up to 3/4 of HP. They consist of a coil whose ends are connected in series to the main winding of the motor, so the entire supply voltage of the main winding passes through the relay coil, so the magnetic field developed in the relay coil is proportional to the intensity developed in main winding contacts. Voltage relay contacts are always open only when the motor starts up to power the auxiliary.
