hermetic. The other leg of the power supply (black wire) is connected to one side of the capacitor and to the run terminal. The other side of the run capacitor is connected to the start terminal on the compressor. These connections place the motor windings in parallel (from one side of power supply to the other), with the capacitor in series with the start winding. The overload is connected in series with the common terminal. 25.3.4 Capacitor-Start, Induction-Run Motor The capacitor-start, induction-run (CSIR) motor is used when a motor must start under a heavy load, but once started, the motor can operate with just the run winding. The open-type CSIR motor is found where V-belts connect the motor to a load, such as an open-type compressor or a centrifugal (squirrel cage) blower. Hermetic PSC Motor Hermetic compressors using PSC motors are popular for residential air conditioning systems because they use R-22 and the capillary tube or metering orifice types of metering device. The metering device permits the system to unload (reduce head pressure) during the off cycle, which permits use of a low-starting-torque motor. However, during the run cycle, R-22 has high head pressure, which requires the use of a motor with high running torque. The PSC motor satisfies both these requirements (low starting torque and high running torque). It also eliminates the need for a relay since the start winding is not disconnected. Electrical Connections. Connections to the PSC motor in a hermetic compressor are made to factory- installed insulated terminals extending through the steel shell. As shown in Figure 25‑26, one leg of power supply (white wire) is connected to the overload at Terminal 1. Terminal 3 from the over- load is connected to the common terminal on the Regular Rotation Wiring Reverse Rotation Wiring A B Image courtesy of Johnstone Supply Figure 25‑25. Wires supplied on a PSC motor to be able to change rotation. A—Purple to purple and orange to orange. B—Purple to orange and orange to purple wiring. Chapter 25 Motors 499 Copyright Goodheart-Willcox Co., Inc.