06-06-2012, 03:40 PM
Electronic starter for single phase induction motors
with starting capacitor or double capacitor
induction motors.pdf (Size: 210.67 KB / Downloads: 8)
Description
To generate a rotating field to start the single phase
induction motors type EAS and EDS from EMG, an
auxiliary winding with start capacitor is used. This causes
a higher starting torque for these types of motors. After
the start of the motor the starting capacitor is cut off.
Due to the motor type, the auxiliary winding may be
energized by a running capacitor in steady-state (type
EDS).
Running the new electronic starter:
During switch-on the motor, the circuit of auxiliary
winding and starting capacitor is closed by a wear less
electronic power switch. This switch opens if the voltage
at the auxiliary winding reaches a level which is typical
for a started motor. The start-up time depends on the
load. Due to the thermal capacities of the motor and the
electronic starter, the maximum start-up time is limited.
To protect motor and electronic starter the switch opens
after 5s. If there is no safe starting possible a motor with
a higher starting torque is needed. The auxiliary
windings of EMG-motors and of the electronic starter
are matched for best performance. After starting, the
electronic starter is blocked until restart.
Security
The electronic starter doesn´t provide any security
functions and it does not replace the function of the
protective motor switch. During overload condition the
auxiliary phase is not automatically connected again.
Perhaps with an enterprise with under voltage (isolated
plant, strongly loaded construction site nets) the
necessary starting current cannot be achieved and the
motor does not start.
Caution:
The electronic starter is matched and tested with EMG
motors type EAS and EDS. These motors are used in
applications that need a short but high peak of starting
torque. For the case of heavy duty starting longer than 5
seconds, these motors are not suitable. With
employment of the electronic starter at unknown
engines it must be guaranteed that the split field
achieves the necessary cut-off voltage at the correct
number of revolutions.