Current relays are often seen when capillary tubes or fixed orifices are used as metering devices; the reason being that systems employing capillary tubes and fixed orifices as metering devices will equalize pressures during their off cycle. This will cause a lower starting torque than systems that do not equalize their pressure during the off cycle, as with a conventional 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.