Motor protector 11

Published:2011/4/27 21:18:00 Author:Ecco | Keyword: Motor protector | From:SeekIC

The motor protector described in the example has the protection function of phase auto delay and the features of simple circuit, without an external power supply, and it is suitable for all kinds of automatic (or manual) three-phase AC motor control equipment. The working principle The motor circuit protector circuit consists of capacitors CI-C5, diodes VDl-VD5, resistors Rl, R2, zener diode VS, light-emitting diode VL, VU prison junction transistors and relay K, it is shown as Figure 8-47. When the three-phase power ofLl-L3 being normal, the AC voltage on junction point A of capacitors Cl-C3 will be lower, the voltage is rectified by the VDl-VD4, after being filtered by C4, it is insufficient to turn on VS and VU, K does not pull, the motor M operates normally. When the three-phase power in the absence of a phase voltage, the place between the zero line and A point will quickly produce l2V AC voltage. This voltage is rectified by VDl-VD4 and filtered by C4, so that making VS breakdown conduction, C5 starts charging, after delaying several seconds (after C5 charging), VU turns, VL is lit, K pulls in, the contacts are off, so that the AC contactor KM releases, cutting off the working power source of motor M. When the three-phase power is restored to normal, after a short delay, VU is off, K releases, then you can press the start button S2 to restart the motor.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/Protection_Circuit/Motor_protector_11.html

Print this Page | Comments | Reading(3)