Brown, orange and red throw me into a tailspin…There is a joke about color blind electricians somewhere in there.
Brown, orange and red throw me into a tailspin…There is a joke about color blind electricians somewhere in there.
You are right that it makes no difference whatsoever to the electrons; only to electricians and maintenance etc. A lot of the concept I posted involves information getting lost in translation. Look at the bigger picture and say you are balancing overall the L-L single phase loads across multiple sub-panels, but the panels are connected sporadically/in random order without specific phase identification. That makes it a lot more difficult to keep track of, especially during maintenance where it could be reconnected in a different order. It is like drawing straws; the system could be started after re-torquing/cleaning and by chance find that a significant chunk of the major L-L loads are on the same two phases.
Safety, is ensuring the correct leg of a circuit is turned off (that could be the fault of an electrician poorly depending too much on the colour of a wire or its identification). For proper equipment function, that would be phase rotation of simple motors primarily. Some VFDs will also complain about it with an error code.
Installations where a certain colour of wire or indication tape is consistently matching the respective phase make these issues a lot easier. Having three black wires for example, leaves a lot of room for error or guessing.
But in what situations does knowing the rotation make a difference? Only if you know the rotation needed by what you are powering and how often is that defined on the equipment?Phase rotation works well if you keep track. Same connection throughout should give you the same rotation.
Grain augers. Aeration fans.But in what situations does knowing the rotation make a difference? Only if you know the rotation needed by what you are powering and how often is that defined on the equipment?
Had an asphalt plant that was built from new.Phase rotation works well if you keep track. Same connection throughout should give you the same rotation.
Somebody didn't do their homework first.Had an asphalt plant that was built from new.
When it was time to turn the power on, the GC asked me if we could swap the primary leads in the transformer if the rotation is backwards. They said they wired everything up the same way so all the rotation would be the same.
We do not like to do that for uniformity across the system, but to be nice I said sure. But only If we could try three or four motors first before we swapped anything.
First and second motor were backwards, he was proud until he got to the third motor..
Thought about sticking around to see just how many went opposite directions, but figured it wasn’t my business, so I left them to figure it out.
These come with the required rotation identified and so marked on the connections?Grain augers. Aeration fans.
Generally on a project the rotations are the same. Get one of each correct and the rest can be wired identically.These come with the required rotation identified and so marked on the connections?
Ok fair enough if you have multiple of the same product. I wonder how often products are consistent though. We had multiple identical RTU's on a project and they were all random.Generally on a project the rotations are the same. Get one of each correct and the rest can be wired identically.
The only time I worked with RTUs, they both had 3 different colors of wire: blue, pink, and yellow. I connected both with the wrong rotation; afterwards I learned that red/yellow/blue is the designation for A/B/C phase in India and SE Asia. It comes from an old UK color code that's not used anymore, but I guess it's still used where those RTUs were manufactured.Ok fair enough if you have multiple of the same product. I wonder how often products are consistent though. We had multiple identical RTU's on a project and they were all random.
I never seen a VFD that input phasing matters. The front end of the drive is a rectifier and you get DC output from it regardless what the input rotation is. Can even have a lost input phase with many of them and they continue to run as long as motor being driven isn't too heavily loaded.You are right that it makes no difference whatsoever to the electrons; only to electricians and maintenance etc. A lot of the concept I posted involves information getting lost in translation. Look at the bigger picture and say you are balancing overall the L-L single phase loads across multiple sub-panels, but the panels are connected sporadically/in random order without specific phase identification. That makes it a lot more difficult to keep track of, especially during maintenance where it could be reconnected in a different order. It is like drawing straws; the system could be started after re-torquing/cleaning and by chance find that a significant chunk of the major L-L loads are on the same two phases.
Safety, is ensuring the correct leg of a circuit is turned off (that could be the fault of an electrician poorly depending too much on the colour of a wire or its identification). For proper equipment function, that would be phase rotation of simple motors primarily. Some VFDs will also complain about it with an error code.
Installations where a certain colour of wire or indication tape is consistently matching the respective phase make these issues a lot easier. Having three black wires for example, leaves a lot of room for error or guessing.
Motors don't care about conductor color, they care about the rotation.The only time I worked with RTUs, they both had 3 different colors of wire: blue, pink, and yellow. I connected both with the wrong rotation; afterwards I learned that red/yellow/blue is the designation for A/B/C phase in India and SE Asia. It comes from an old UK color code that's not used anymore, but I guess it's still used where those RTUs were manufactured.
I believe motors designed per NEMA typically will all run the same direction if you connected same input sequence to them. So if you are keeping track of what phase is which with your circuit conductors you should reliably be able to predict motor rotation. Needs of the machine can vary though.Ok fair enough if you have multiple of the same product. I wonder how often products are consistent though. We had multiple identical RTU's on a project and they were all random.