The Klixon 4CR current type motor starting relay is a compact, high capacity relay, designed for universal application to splitphase and capacitor start,
single-phase motors with start-winding currents up to 25 amperes.
- Reliable operation and long life independent of mounting position
- Wide range of pick-up and drop-out ratings
- Start-winding current rating – 25 amps
- Small size for installation in compact equipment
The 4CR relay utilizes a balanced armature to provide positive operation
independent of mounting position. Double-break bonded Top-lay contacts
provide excellent electrical and thermal conductivity to provide the high
switching capacity and long electrical life. Silver cadmium oxide is used for
the 25 amp contacts.
Pick-Up and Drop-Out Ratings
Ratings indicated maximum pick-up and minimum drop-out current limits. Pick-up is the current through the relay coil required to close the relay contacts.
Drop-out is the current through the relay coil at which the contacts open. A production relay of a given rating will have a pick-up and drop-out current within
the rating limit.
The 4CR relay coil is in series with the main winding of the motor and the normally open contacts are in series with the start winding. When voltage is applied
to the motor, the in-rush current of the main winding through the relay coil creates a magnetic force which rotates the armature. This action closes the relay
contacts and energizes the motor start winding.
As motor speed increases, the current in the main winding and relay coil decrease to a point where the armature biasing spring force is greater than the
decreasing magnetic force, and the armature rotates back to its original position. This opens the relay contacts and disconnects the start winding.