Phase reversal detector


Posted on Mar 29, 2013

Assume the correct phase sequence to be VA-VB-VC. The circuit terminals are connected such that Tl gets connected to phase A and T2 to phase B. The capacitor advances the voltage developed across R2 due to phase `B` by — 60°, while the voltages developed across it by phase `A` is in phase with VA as shown in Fig. 69-1. The net voltage developed across R2 ~ zero, the neon lamp is not energized, thereby signaling correct phase sequence. If terminal T2 gets connected to phase C, a large voltage, K(VA + Vc 60°), gets developed across R2, energizing the neon indicator to signal reverse phase sequence. The motor terminals can be connected to the three phases in six different combinations.


Phase reversal detector
Click here to download the full size of the above Circuit.

A three-phase motor will run in the forward direction for three such combinations, while for the other three it will operate in the reverse direction. As shown in the table, the circuit detects all three reverse combinations. This circuit can be wired into any existing motor starter where the operator can see whether the phase sequence has been altered, before starting the machine.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Bass Guitar Compressor
Auto Fuse for power supply
Systems Design Datagoo documentation
Infrared proximity sensor serial Si1143 of Silicon Labs Company
Baud Rate Generator
Fun card
Zhichuan Electronic Circuit
50 to 150MHz high frequency VCO circuit



Top