Starting relay

Starting relays – general product information
Starting relays are a group of automatic temperature controllers for the self-starting of single-phase short-circuit induction motors with an auxiliary starting phase, used to drive compressors in domestic refrigeration equipment. These relays have a simple and compact design. The body is made of plastic with high mechanical properties and meets all requirements under safety standards. These relays are adapted for mounting directly on the grommet studs of the compressor housing.

The principle of operation of the PR relay
When the compressor is switched on, current flows through the main winding of the compressor motor C – W and through the coil winding of the starting relay. The flowing current pulls the steel core upwards and closes the contact elements 2 and 3, which means that the starting winding is switched on
C – S. When the rotor of the compressor motor reaches about 80% of the synchronous speed, the current
in the main winding C – W and in the relay coil decreases, as a result of which the core, under the influence of its own weight, drops down disconnecting elements 2 and 3 and switching off the starting winding.
The motor rotor reaches the rated speed already without further participation of the starting winding.