Phase Failure Three Phase Voltage Relay Overvoltage CE / CCC Certification

Phase Failure Three Phase Voltage Relay Overvoltage CE / CCC Certification

Phase sequence protector principle

Phase Sequence Protector Principle Under normal circumstances, the wiring order of the motor work is regulated. If for some reason, the phase sequence is disordered, the motor will not work properly or even be damaged. Phase sequence protection is to prevent such accidents from happening.

Phase sequence protection can use phase sequence When the phase sequence in the circuit does not match the specified phase sequence, the phase sequence relay will trigger the action and cut off the control circuit so as to cut off the motor power supply and protect the motor.

Three-phase alternating current phase sequence detection circuit is composed of helium bubble NB. Due to the phase-shifting effect of C1, when the power supply is connected in the phase sequence of A, B, and C in the figure, the helium bubbles emit light, and when the reverse phase sequence is connected to A, C, and B, the helium bubbles are not bright.

When the start button QA is pressed, the alternating current is depressurized by C2, VD1, and rectified and DW to obtain a DC voltage of 12V, which is added to the protection execution circuit composed of the relay K and the photosensitive resistor tube V. If the order of the phases is A, B, and C, then the helium bubbles emit light, and the CDS packaged with the helium bubbles exhibits a very low impedance after being irradiated with light, and then V gets a biased base current and conducts. K picks up, K1 Connect the AC control circuit, C pulls in and the motor starts running. On the other hand, if the reverse phase sequence is followed, the bubble does not light, K does not pull, and K1 turns off, and the motor cannot be started. This achieves the purpose of protection.

Features

Phase sequence protection device can be divided into two types: contact phase sequence protector and non-contact phase sequence protector. The former uses electromagnetic relays or AC contactors as its actuators, while the latter uses solid-state relays (thyristors, IGBTs, high-voltage VMOS transistors) as its actuators. The former uses the contacts of an electromagnetic relay or AC contactor to break the phase-sequence faulty three-phase power supply, while the latter uses an electronic component to turn off the faulty power supply. Therefore, compared with the former, the latter has the characteristics of fast response, no noise, no spark, long life, small size, and high mechanical strength. The former is relatively the latter, has a high breakdown pressure, withstand overload, low cost, etc. Features.

Three-phase monitoring of phase sequence, phase loss, over- and undervoltage and phase unbalance

♦ Technical data