Copyright Goodheart-Willcox Co., Inc. Chapter 13 Electric Motors 261 13.3.2 Capacitor-Start, Induction-Run A capacitor-start, induction-run (CSIR) is wired in series with the start winding and causes the phase shift between the run and start winding to approach 90°. As a result, the motor produces higher starting torque. This motor is suitable for larger refrigeration compressors, pumps, and air handlers. The start winding must be discon- nected like the RSIR, Figure 13-15. The start winding wire diameter is thicker than the start winding of an RSIR motor due to the increase in current flow. When the start winding is removed, the CSIR operates the same as the RSIR. The only difference between 1/2 hp RSIR and a 1/2 hp CSIR is that the CSIR requires more starting torque to move a specific load, such as a refrigeration compressor. 13.3.3 Permanent Split Capacitor As the name implies, the phase in a permanent split capacitor (PSC) is always split as the motor operates because the start winding is left in the circuit. Thus, it does not require a device to remove the start winding. A run capacitor is wired in series with the start winding and improves the operating power factor. See Figure 13-16. A PSC is not a high-starting torque motor like a CSIR. It has a low to moderate starting torque and is used for evaporator blowers and air conditioning compressors up to three tons. Split-Phase Motors Split-phase motors operate on single-phase power of 120 V and above. L2 can represent either a neutral supply for 120 V or a hot leg for 208 V and higher. Some manufacturers may place L2 on the common terminal instead of L1 even if L2 is a neutral wire. When the hot and neutral wires require a definite connection to the motor, the hot wire is tagged as the ungrounded side of the line. Pro Tip S R L2 C L1 CSIR Centrifugal switch Goodheart-Willcox Publisher Figure 13-15. CSIR motor diagram. S R L2 C L1 PSC S Lo Med L2 C L1 Multi-speed PSC Hi Goodheart-Willcox Publisher Figure 13-16. PSC motor diagram single and multi-speed.