Phase sequence

[Engineer54]

Ive got the Kewtech 1710 voltage tester for proving circuits dead, this also gives you phase rotation indication between two phases, quite a handy bit of kit

Not sure this would give you true 3 phase rotation? Anyone that works with 3 phase supplies should be in possession of a phase rotation/sequence meter, it's an absolute must have bit of kit. There not expensive either!!!

 

[Graeme Harrold]

Not sure this would give you true 3 phase rotation? Anyone that works with 3 phase supplies should be in possession of a phase rotation/sequence meter, it's an absolute must have bit of kit. There not expensive either!!!

What do you mean by true 3 phase rotation. You either have the correct sequence or you dont. By referencing two phases one with either lead or lag the other....simples

 

[topquark]

If the suggestion is that it's necessary to test the phase angle between phases, that's overkill IMHO. Just testing the rotation sequence should be sufficient.

 

[Engineer54]

If the suggestion is that it's necessary to test the phase angle between phases, that's overkill IMHO. Just testing the rotation sequence should be sufficient.

Tell that to the Factory Engineer and see what happens!!! As i said, if your going to be working on 3 phase stuff, especially in controlled environments you will NEED a phase sequence/rotation meter. A factory or large commercial system tends to have there 3 phase systems sequence unified throughout the installation. if you come along and alter that sequence, they won't be happy pilgrims. It tends to be even more important where the installation is supplied by 2x TXs.... So you see , it's only over kill to those that are not aware or haven't worked in industrial production situations....

 

[topquark]

A sequence/rotation meter does not test the phase angle??? Which is what I was asking.

 

[Engineer54]

The better ones WILL!! But, as you say....if you start with the known phase as phase 1 then it's a simple matter of finding the other two phases sequence. The problem comes when all conductors are the same colour. Which is why many such installations are phase coloured throughout the entire installation.

Remember, on the MV side of things, it's difficult to keep the RST sequence, often to achieve that sequence, the incoming cable needs turning. So in reality, the actual sequence on the LV main panels can be anything but RST, but can sometimes still be distributed as RST but could well be TSR for argument's sake....

Look , all i'm trying to say is, that in quite a few situations Sequence is very important in particular scenarios!!!

 

[topquark]

That's excactly what Graeme was saying, I think you'll find. We were trying to understand what "True Phase Rotation" was.

 

[Engineer54]

The better ones WILL, the same as RCD testers will show phase angle!!!

 

[topquark]

Perhaps if I simply phrase the question: "What is True Phase Rotation as opposed to Phase Rotation"?

 

[Engineer54]

Basically to whatever the sequence is at the LV main Switchboards... It can sometimes be very difficult to get MV supply cable to connect as RST without difficult cable turning, so more than possible that LV connection to TX is TSR, but will generally still be connected RST!!

Look, all i'm trying to say is that Sequence can be very important in certain scenarios. Engineering managers tend to want to keep the same sequence throughout the plant/factory, same for Engineer in the larger commercial enterprises...

In the perfect world, True Phase sequence would always be RST... LOL!!

 

[topquark]

I think we're were all agreed that the sequence/rotation is important, but as stated, sequence is sequence. I'm struggling to understand what "True" adds to the equation, is there maybe some tollerance in degrees/radians for the timing of each phase? It would normally be 120Deg (or 2Pi/3 radians) for the timing of each phase.

 

[Engineer54]

My terminology i'm afraid, of trying to briefly describe my point about sequence... Sorry!! lol!!!

 

[topquark]

Ah, OK, thought I was missing some understanding, ta!

 

[Engineer54]

Ah, OK, thought I was missing some understanding, ta!

Have to appologise for seemingly repeating myself here too...lol!! 2 or 3 times i thought i'd lot my post text, but it seems it did get through on the main board, just wasn't showing up on my screen... lol!!!