3 phase motor rotation detection.
3 phase motor rotation detection.
(OP)
Is there any hardware out there that will correct the rotation of 3-phase power input to a specified rotation? I have an application for a 3-phase motor (3 to 10 hp) that is on a portable conveyor, and can be moved from one power receptical to another. The portability of this device is such that it will operate at one site, and then be moved to another location. The 3-phase power supply may be clockwise, or counterclockwise, but I must guarantee that the motor will start the same direction each time. I'm not looking at phase correction, I'm looking for rotation correction. It would detect CW or CCW in the power supply, and output a corrected phase rotation. A reversing drum switch will not work for this application because it requires human input. The rotation correction must occur automatically.





RE: 3 phase motor rotation detection.
Good inexpensive brands:
Time Mark
SSAC (now ABB I think),
Diversified /ATC
Symcom
Syrelec / Crouzet
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: 3 phase motor rotation detection.
Barry1961
RE: 3 phase motor rotation detection.
When the relay detects the correct phase then the fwd. will enable when the phase is incorrect then the rev. will enable.
RE: 3 phase motor rotation detection.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: 3 phase motor rotation detection.
You probably know this but for those who don't;
The circuit that you describe is standard on many container mounted refrigeration units. For reasons that have been described in another post, reversing an older refrigeration compressor may lead to lubrication failure, hence the automatic phase correction.
yours
RE: 3 phase motor rotation detection.
The first phase relay could be fooled by a loss of phase so the second phase relay must be used. The second phase relay would provide a delay (so the reversing relay isn't switching under load) with checking for a lost phase or low voltage as well as correct phasing.
RE: 3 phase motor rotation detection.
RE: 3 phase motor rotation detection.
I just checked a typical scymatic. They use a reversing contactor. A phase rotation relay (Or protector) closes one or the other of the contactors depending on the phase rotation. A third motor starter is used for motor starting.
I think you can find them at www.thermoking.com
Search drawings - Product Thermo King
yours
RE: 3 phase motor rotation detection.
3HP regular motor starter ~ $120
Cheap phase monitor relay ~ $120
----
$420
3HP 230V inexpensive VFD ~ $300
Even if you don't use the second starter to maintain normal control, I'd still use the VFD. Less wiring and more flexible.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: 3 phase motor rotation detection.
At those prices, I have to agree with you.
Many of the container units were dual voltage 240-480. They have an internal transformer to match the voltage when needed. The pricing for 480 volt equipment probably skews the economics in favor of the starters.
yours
RE: 3 phase motor rotation detection.
RE: 3 phase motor rotation detection.