In many respects single phase motors have the same properties as three phase motors, and mechanically they meet the same standards. There are several types of single phase motors (CSR, PSC and PSC-reg.).
Description and application
Starting and run capacitor ( YL series single phase motor, also called YC, YCl, or ML)
Single phase motor with attached run capacitor, starting capacitor and electronic start relay mounted in the terminal box.
The electronic start relay connects the starting
capacitor instantly when the motor starts, and cuts
out when the motor has reached its break-down
torque. The connec-tion time is limited to max. 2 sec.,
after which the starting capacitor is disconnected,
regardless of whether the motor has reached its
breakdown torque. The starter relay cannot reconnect
until the mains voltage to the motor has been
disconnected; this protects the starting capacitor and
ensures that the motor can be protected with a thermal
motor line circuit breaker.
The CSR motor with a starting torque of 140 - 160%
is suitable for applications that require a high starting
torque, such as compressors, hydraulic pumps that
start with back pressure and centrifugal pumps where
the shaft seal requires a high breakaway torque.
Single-phase motor with attached run capacitor. The
starting torque is 30 - 70%, which makes this motor
particularly suitable for applications with low starting
torque requirements, such as fans, circular saws,
polishing machines and centrifugal pumps where the
shaft seal does not require a high breakaway torque.
for speed regulation
The motor’s speed can be regulated by changing the
voltage to the motor (twin-cable regulation) or by only
changing the voltage to the circuit winding (three-cable
regulation). The best regulation and the minimum loss
in the motor is achieved only by changing the voltage
to the circuit winding.
The voltage can be regulated using a tranformer or a
Triac control. The Triac control provides a greater loss
in the motor and can contribute to noise in the motor.
To achieve good speed regulation it is important that
the motor is suitable for the load. If the motor is too
large for the load the regulation range will be small; at
full speed the motor should not be loaded with less
than 80% of its full load. With correct dimensioning it
is possible to regulate speed down to approx. 30% of
Speed regulation is suitable for the following applica-
tions: fans where blades are mounted directly on the
motor shaft and centrifugal pumps where the shaft seal
does not require a high breakaway torque.
Standard single phase motors cannot run idle for a
long period. The losses are greater when running idle
than at full load. If the motor is to run idle for a long
period, specially designed windings must be produced.