Current relays are often seen while narrow tubes or fixed orifices are used as metering machines; the idea being that systems using capillary tubes and fixed cracks as metering devices will equalize pressures during their off-cycle. This will make a lower offset torque than systems that do not balance their pressure during the off-cycle, as with a regular thermostatic expansion or automatic expansion metering device.
Some typical applications for current relays on compressors might include domestic refrigerators, drinking fountains, small window air conditioners, smaller ice machines, and smaller supermarket display cases.

Current relays consist of a low resistance coil and a set of normally free contacts. The coil is filed between terminals L and M. The contacts are wired between terminals L and 2 when a start capacitor is used. If the start capacitor is not used, the contacts may be wired differently between terminals L and S. Terminals L, S, and M are typical identifier ends for current relays. L is for Line, S is for Start winding, and M is for Main winding. This should support engineers wire a current relay to a compressor's motor.

Remember, when a source capacitor is being used, terminals 2 and 3 may come into play. Also, when wiring capacitors to a motor using a current relay, always wire the starting capacitor in series with the start winding. The run capacitor will forever be wired within the run and begin winding terminals. Additionally, recognize that different manufacturers may change their terminal designations slightly.