Electric Motors
The electric motors used to power mechanical refrigeration equipment are commonly of the following two types:
1. Single-phase induction motors
2. Three-phase induction motors
The single-phase induction motors are usually classified by the method used to start them. Among the more common ones are the following:
1. Split-phase motors
2. Capacitor-start motors
3. Permanent-split capacitor motors
4. Capacitor-start, capacitor-run motors
Capacitor-start and capacitor-start, capacitor-run motors are described in Chapter 6 (“Other Automatic Controls”) in Volume 2.
Either capacitor-start, capacitor-run or three-phase induction motors can be used to power compressors. The latter are normally used when three-phase current is available.
Troubleshooting Electrical Motors
Table 9-2 lists the most common operating problems associated with electric motors. For each symptom, a possible cause and remedy are suggested.
Gas Engines
A four-cylinder water-cooled gas engine using natural gas as the fuel can be used to power the compressor (and sometimes the con- denser fan). It is normally mounted in a weatherproof cabinet out- side the residence where venting is not a problem. Because an internal combustion engine must be vented, electric motors are by far the most popular type used for powering mechanical refrigeration equipment.