Phase angle

fonager · Jun 13, 2011

On a 400 v transformer i need to locate the 3 phases is it right that phase L1 is 0/360 degrees angle and L2 is in 120 degrees angle and L3 is in 240 degrees angle? Is the best and cheapest way to measure that with clampmeter ? It is important to know the phase angle because we need to phase to tranformers together.

Knobhead · Jun 13, 2011

You are right about the phase angles but you can’t measure phase angles with a clamp meter.
If the two transformers are of the same vector group (say DyN1) then RYB connected to ABC will give corresponding phase angles but 60° retarded. So RYB in = ryb 60° shifted.

A voltmeter will confirm the phasing is correct. So long as they share a common neutral.

Test between Tx1 and Tx2 and you should get the following readings

-----------Tx1----------Tx2
------------r----->-------r = 0V
------------y----->-------y = 0V
------------b----->-------b = 0V
------------r----->-------b = 415V
------------b----->-------y = 415V
------------y----->-------r = 415V

To be honest I’m worried about you asking these questions. Depending on the size of the transformers you have to know what you’re dealing with. For Christ’s sake don’t use you’re MFM, you need fused test probes as a minimum safety requirement.

It is bloody dangerous!

fonager · Jun 13, 2011

Forget the first question I try to rephrase it.

I have 2 transformers let us call them a and b.

If the 2 transformers are not installed identical so I can get a voltage of 230 volts between phases.

This clamp meter could do the job.

Dilog DL6409 Digital Power Clamp Meter http://www.test-meter.co.uk/index.php?_a=viewProd&productId=490

Measures:
► Phase Angle

mechelec · Jun 13, 2011

I would have thought an oscilloscope would have been better as you could compare the phases from each TX and check phase angle alignment

fonager · Jun 13, 2011

can you tell me have to do this?

madmac · Jun 13, 2011

No offence fonager but the fact that you're on a forum asking some very technical advice about the phase angle of two seperate transformers that I'm assuming you want to run in harmony, seems a very dangerous road to be going down and you don't seem to have enough technical experience from your questioning to able to safely and competently carry out this procedure. So as Tony is hinting at, just be careful mate.

fonager · Jun 13, 2011

Dont worry guys!!!!!!

VoltzElectrical · Jun 13, 2011

scary!

Knobhead · Jun 14, 2011

What size and vector groups are the transformers? What do you mean by they are not installed identical?

To measure phase angle you need to have a base signal or source to compare to, what are you using as the base signal?

If you are thinking of using two transformers of different vector groups and paralleling them, your heading down a dangerous road. Circulating neutral currents being one problem, toasting the earthing arrangements even more worrying. It’ll bring a whole new meaning to the “Big Bang” theory.