ECN Forum Forums General Topics of the Trade General Discussion Area Phase/Motor rotation meter

I'm planning on purchasing a combination Phase/Motor Rotation meter soon. Which ones are best... or to stay away from?

Also, how well does the motor rotation part work? Tips, tricks, & traps?? I've never used one of these before.

Thanks in advance for all replys.

I have a REALLY old one that has a small wheel that spins clockwise, or counter-clockwise. It is indestructable!

Shop has one with two lights on it simular to this, but an old easy to loose case. Shows A-B-C, or C-B-A. Also really hard to break.

Both are pretty fool proof...

I used to have a really good one that Greenlee /BEHA made. It dissapered from my tool box back when I used to have employee's. I do not remember the cost of it but I'm cheap

I've seen them but never used them.
To find the rotation of the line in you just connect A-B-C to the meter right?
but what about the moter?
How do you find rotation of moter? Would it be A-B-C to L1-L2-L3
Can someone tell me how?

Here's a good one,
It's a Martindale:
{NB: This is a 415VAC model}



Generally, I've always just tested a motor under no-load conditions, with a short burst of voltage (using appropriate safety parameters), to check which way it is running.

Most equipment is wired clockwise, and equipment with multiple motors are also clockwise. It the case with AC units, or elevators you could damage the equipment by reversing it, even for a short time. And yes, it would be A-B-C to L1-L2-L3, although you should always check. Most 3-phase equipment will have an arrow on or near the motor. If not, it would be clockwise as you are looking from the back of the motor at the shaft. For the most part, I won't start equipment, I let the responsible party do that, I just provide clockwise. And if doing a service or panel change I check to see what it is before I demo, then provide the same back. I have come across older buildings done counter-clockwise, and every item installed over the years reversed. If its a sizable building you might never find all the things you would have to change, and be dangerous if you didn't find them all. And if you do change something, make sure to mark it.

IBM operated for about a quarter of a century without a 3p standard. They said it was clockwise but there was always the argument whether that was clockwise at the plug (the plant's view) or the receptacle (the electrician's view). The standard task for the hardware installer was to plug it in, see which way the motors ran and swap it in the equipment if it was wrong. Some equipment was shipped with a reversing jumper right in the primary power box. Finally, some time in the Reagan administration, they decided enough is enough and gave the guys a rotation tester.
(A $5 adapter doodad that worked with a regular VOM)
Things still got swapped in the machine occasionally but the rule was we were supposed to get the electrician back to fix it. That standard was clockwise at the face of the receptacle.
When "big iron" gave way to the current cludge of "PCs in a rack" everything is basically single phase, even if the source is 3p. By the time I left in 96 there weren't any new products with 3p motors, big or small.