Current three-phase motor phase protection circuit, as shown in FIG. 3 homemade small current transformers Tl, T2 and T3 on the motor is running three-phase current detection s
ignals are collected by the VDl, VD2 and VD3 rectifier, Cl, C2 and C3 filter by VD4, VD6 and VD8 oR gate circuit is composed of R4, R5 partial pressure of the supplied voltage comparator Al-inverting terminal; the gate as a three-phase current output circuit to identify the presence or absence VD5, VD7, VD9 composed of input voltage comparator Al counter phase terminal.Transformer Tl ~ T3 making available on the market Tesco toroidal ferrite core with µ0.25mm high-strength wire, winding 150 to 250 turns. The number of turns is determined by the power of the motor, motor power small can around more. Through the power cord from the ring, as the primary winding. Capacitor C1 ~ C3 electrolytic capacitor 10 F/25V of; C4 use 0.1 F/63V ceramic capacitors; C6 electrolytic capacitor 470 F/25V is; C5 is interference absorption capacitor, to increase the capacitance value C5 when the action is too sensitive, Conversely reduce the value of C5, which is in the range of 4.7 ~ 33 F/25V. Resistance Rl R2 l.2k, R4 390k, R5 680k, R6 15k, R7 2k, nominal power are RJ resistance 1/8W of. Zener diode VD11, which the regulator is about 8V. Other diodes with 1N4004.