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A Protection Circuit of Default Phases of Three-Phase Three-

2016-09-22 19:14  
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A Protection Circuit of Default Phases of Three-Phase Three-Wire Power Sources
The following is a circuit used toprotect the defult-phases of three-phase three-wire power sources. Without anyone of A,B or C, the electrical level (LEV) that the optical coupler output will be lower than the reference voltage that the inverting input node of the comparator holds, and the latter will low LEV to block the PWN driving signals, finally, the supply power will be shut down. Besides, if the input polar of the comparator changes, the PWM signals can also be blocked by high LEV. This circuit separates heavy currents by optocouplers, which is safe to use, while RP1 and RP2 are used to adjust the threshold values of the protecting behaviors.