Motor Basics
General Purpose Split Phase
Characteristics
The split phase type motor is most widely used for single voltage ratings, 1 HP or less, and for applications where starting torque requirements are 200% or less of full load. The split phase motor has a start and run winding. Both windings are energized when the motor is started. When the motor reaches about 75% of its rated full load speed, the start winding is disconnected from the circuit by an automatic switch.
Applications
Common applications of split phase motors include: fans, blowers, pumps, office machines and tools, such as small saws or drill presses where the load is applied after the motor has obtained its operating speed.
General Purpose Capacitor Start
Characteristics
The capacitor start induction run type motor is most widely used for dual voltage ratings, 2 HP or less, and for applications where starting torque requirements are 350% or less of full load. The capacitor start induction run motor has a run winding and a start winding with a capacitor connected in series. Both windings are energized when the motor is started. When the motor reaches about 75% of its rated full load speed, the start winding and start capacitor are disconnected from the circuit by an automatic switch.
Applications
It has good efficiency and requires starting currents of approximately five times full load current. Common applications include: compressors, pumps, machine tools, air conditioners, conveyors, and other hard to start applications.
General Purpose PSC
Characteristics
The permanent split capacitor motor (PSC) is compact, easy to maintain, highly efficient and has a high power factor. The permanent split capacitor type motor is most widely used for 2 HP or less and for applications where starting torque requirements are 100% or less of full load. The permanent split capacitor motor offers smooth acceleration and has a run winding and a start winding with a capacitor connected in series. Both windings are energized when the motor is started and running. No switch is required to switch any component out of the circuit.
Applications
A major advantage of the PSC motor is the capability of operating at different speeds by allowing higher levels of slip. Special applications include: fans and blowers, air conditioners, coolers, furnaces, unit heaters, roof ventilators, dehumidifiers, garage door openers, and other applications that require low starting torque and current.
Typical Polyphase Design
Characteristics
The three-phase motor has excellent starting torque characteristics, yet the normal starting circuit requirements are low compared to single phase motors. The three-phase motor can achieve locked rotor torque up to 400% of full load torque. Its high starting torque and capability to achieve high efficiency enable the motor to drive practically any equipment where load must be brought up from standstill to operating speed smoothly and quickly.
Applications
Popular applications include: grinders, lathes, drill presses, pumps, compressors, conveyors, also printing equipment, farm equipment, electronic cooling and mechanical duty applications.