Phase Sequence Analyzer

[inchoate]

Hi guys,

can anyone tell me how useful is a Phase Sequence Analyzer? Does it really can prevent the motor from spinning in the wrong direction?

Thanks.

 

[dpc]

Only if the motor leads are identified by phase sequence. This is not standard for smaller motors. Larger motors and generators are usually better marked.

The phase sequence indicator definitely works and will tell you the phase rotation.

But you're going to want to bump the motor to verify.

 

[busbar]

Devices like the R-K Electronics MRT or Biddle Motor and Phase Rotation Tester are intended for low-voltage motors and systems, but are subject to ‘cockpit error’.

 

[buzzp]

Yes they work. They will prevent the motor from spinning backwards. Generally, the sequence is determined on the utility side then if the motor is not marked, the analyzer is put on the open motor leads and rotated (by hand or other means) to determine the phasing inside the motor. Then the two are hooked together. I do not see a lot of value in continuously monitoring the phase sequence (does not just mysteriously change, especially when running).

 

[panelman]

In my area (pumping) lots of stations have generator inputs too

lose the mains, whistle up a mobile generator, plug it in and you are beck on line

problem is if the generator plug is different order to the mains then every thing runs backwards, pumps don't and if you are really lucky they unscrew their impellers

 

[jbartos]

Suggestion: Visit

http://www.markosinc.com/eshorts/june6.asp

for:
PRM-1 Phase Sequence and Motor Rotation Tester
Identifies the phase sequence of the three phase electrical systems and checks motors for rotation direction. Indicates normal or reversed phases as well as loss of phase. 50-400Hz.

PMR-1 phase and motor rotation tester
PMR-1 phase and motor rotation tester provides three functions in one unit: open-phase indication; 3-phase sequence indication; and motor-rotation indication. Input voltage range is 100V to 600 VAC. Frequency range is 45 top 70Hz. AEMC Instruments, Boston, MA