Three Phase wiring

[Orn Jonsson]

Is there a simple way to test if all 3 phase outlets in the same facility are wired the same way?
If I drag a machine from one corner of the plant to the next, I would prefer that the motor would turn the same way at both locations... (no leg swapping).
Can one use a DMM to test for phase 1, 2, and 3, ?


Thanks,

[Pierre]

These tester are sold everywhere. Not expansive at all and no you cannot test with a DMM.

[Eric Nelson]

As Pierre said, these are readily available. You're looking for a "Phase Sequence" indicator.

HERE'S (http://www.tegam.com/html/phase_motor.htm) one source I found (it's the second item on that page).

Beerchug

-Eric

[rsdoran]

Orn its called a phase sequence or rotation meter...when connected it will rotate clockwise or counter clockwise if an anlog model. Digital versions diplay rotation. Most major meter manufacturers have them.

Amprobe:
http://www.amprobe.com/cgi-bin/pdc/searchprod.cgi?category=54&type=elec&tid=1&action=search

Extech:
http://www.extech.com/newsite/instrument/categories/specialty/subcategory/phase.html

AVO Biddle/megger:
http://www.mitchellinstrument.com/c6061.pdf

There are more but just call your local electrical supply house and they will probably have one in stock.

[JesperMP]

Quick and dirty :

Just use a small 3 phase motor if you have one at hand allready.
Connect it at both places, and observe which way it turns around.

Of course, if you have to do this more than few times, its makes sense to purchase a tester. ;)

[JvdV]

If you really want to use a DDM, it's possible but very dangerous.

Risk you take:
-electrocution ----> DEAD
-Short circuit ----> nice BBQ
-and so on

What I try to say is that you really have to know what you are doing. And even then the risk factor is very, very high.
A little device that the other guy's on the forum mentioned is mutch bether and safer.

You can use a long wire (cable is a lot safer) to connect to the main power supply fase one. At the other end you connect one lead of your DDM. The other lead you put on the wires you want to check. If there is an indication of more than a couple of volts that means you have a different fase at both ends.
In this way your are able to check if the actuale sequens is the same everywhere.

But I cannot say it enough.
DON't use this way if you don't fully understand or if there is a different way of detecting the sequens.
Your life is worth more then a couple of 100 bucks !!!!!!

[Orn Jonsson]

JvdV

"
What I try to say is that you really have to know what you are doing. And even then the risk factor is very, very high.
A little device that the other guy's on the forum mentioned is mutch bether and safer.

You can use a long wire (cable is a lot safer) to connect to the main power supply fase one. At the other end you connect one lead of your DDM. The other lead you put on the wires you want to check. If there is an indication of more than a couple of volts that means you have a different fase at both ends.
In this way your are able to check if the actuale sequens is the same everywhere."

when did checking voltage become more dangerous than it was last week???
are you just checking leg 1 to leg 2 and then leg 1 to leg 3, and looking at voltage differences?

I don't get what the BIG deal is

later

[rsdoran]

What jvdv said is bunk, you can NOT use a meter to determine rotation. A LONG cable should naturally create a difference in potential across the phases. The other question to ask with that scenario is " A difference in reference to what?"

There are old methods using lights connected across phases, some of us had to use these when working with gensets.

A phase meter can be had for around $50 US or so, get the meter OR use a small motor as was previously mentioned.

To me the meter is easier to use and carry, even a small motor costs more than the meter in most cases.

[Eric Nelson]

I think JvdV was suggesting bringing over one of the phases from the remote outlet as a reference. Let's say that wire comes from phase B of the remote outlet. If you measure between that wire and the 3 phases of the local outlet, phase B (on the local outlet) will be the one with little or no voltage.

NOT a method I would recommend though... :rolleyes:

beerchug

-Eric

[JesperMP]

rsdoran: To me the meter is easier to use and carry, even a small motor costs more than the meter in most cases.

Right, but if you have one at hand allready, and cant wait until you get a real meter, then you could do with the motor.