50Hz precision step phase shifter

Thread Starter


Joined Jan 18, 2012
I need to test relay (Directional earth fault protection - ANSI code 67 N). I have a Vref=230Vrms, 50Hz.
I have to apply a voltage V0 to the input relay (Zrelay 2kOhm, Pn 32mVA).
V0 must have the following characteristics:
1) regulable 0-8 Vrms
2) with the phase angle regulable to step angle -54°,-66°,-90°,-114°,-126°,-180°,-244°,-256°,-264°
Who can help me?


Joined Feb 28, 2009
Sounds like a perfect application for a resolver. Excite sin/cos windings with quadrature reference and pull variable phase shift from rotor. Adjustable through 360 degrees.


Joined Sep 20, 2005
Since the frequency is fixed, you could phase shift the voltage using a multistage low pass filter and then use an amplifier to get the needed amplitude back up. Something along the lines of a phase-shift oscillator but without completing the circle and with switching the output to the different stages should work, and since you will be measuring the output voltage anyway you will be setting the make-up gain manually.