Elevator part Three Phase Voltage Monitoring Relay phase failure protective deivce

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

-- Built-in LCD and keypad afford a precise,digital setting

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

-- Adjustable over- and undervoltage, phase unbalance threshold

-- Independent adjustable delay time for overvoltage, undervoltage, phase unbalance

-- Powered by the measuring circuit

-- 1 NO & 1NC contacts

-- Faulure recording

♦ Protective Functions

-- Phase sequence

-- Phase loss

-- Phase unbalance

-- Overvoltage

-- Undervoltage

♦ Typical Applications

• Pumps • Fans

• Blowers • Motors

• Compressors

♦ Approvals

• CE • CCC

♦ Technical data