# Motor Bump Test



## magmash (Jul 20, 2012)

Hi Guys 

Can some one explain what a Motor Bump test is, and how 
its done ?


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## mayanees (Jan 12, 2009)

It's done to test rotation. The start button is pressed for just a "bump", an intermittent push of the button, then turned off immediately if it's a seal in circuit. If it rotates correctly, you're done. If not, switch 2 wires.


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## glen1971 (Oct 10, 2012)

Caution should used when doing it though! Some equipment does not like to run backwards and can be badly damaged (screw compressors, some pumps, etc)... Other pieces may have a phase reversal monitor installed and nothing will happen (hvac compressors usually)...

Uncoupled is the best way when possible...


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## forgotflying (Mar 2, 2011)

Bakery presses don't like being run backwards either, run it backwards and you can expect a large bill for re-calibration.


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## Wirenuting (Sep 12, 2010)

Scroll compressors, AC, don't like being bumped backwards also.


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## ohmontherange (May 7, 2008)

glen1971 said:


> Caution should used when doing it though! Some equipment does not like to run backwards and can be badly damaged (screw compressors, some pumps, etc)... Other pieces may have a phase reversal monitor installed and nothing will happen (hvac compressors usually)...
> 
> *Uncoupled is the best way when possible...*




Long, long time ago... hooked up a faily large- like 75 HP well motor, tightened the headnut, hammered in the lockpin and bumped it. Rotation was backwards. This particular irrigation well was like 400' deep.

Not pretty - my boss called a crew out from the well service company with a pulling rig to fish the uncoupled shaft, bowls, & impeller out of the hole, also had to send the clutch off the top of the motor to a machine shop and have it turned on a lathe.

Not my finest hour.


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## Jlarson (Jun 28, 2009)

Phase and motor rotation meter.


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## MDShunk (Jan 7, 2007)

I'm lucky if I know what direction stuff is supposed to spin, even if I'm looking right at it. Best case scenario, it has an arrow on it someplace.


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## brian john (Mar 11, 2007)

Jlarson said:


> Phase and motor rotation meter.


Was on a job the other day for GFPE tripped. Found a motor smoked (40HP water pump). An installer had been using the motor feeder for operating a welder, upon hooking the motor up they reversed rotation. 

They discovered the error and resolved the issue, next day it fried.

Doubt it was the contractors fault but they will have a tough battle.


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## MDShunk (Jan 7, 2007)

brian john said:


> Was on a job the other day for GFPE tripped. Found a motor smoked (40HP water pump). An installer had been using the motor feeder for operating a welder, upon hooking the motor up they reversed rotation.
> 
> They discovered the error and resolved the issue, next day it fried.
> 
> Doubt it was the contractors fault but they will have a tough battle.


Last guy that touched it owns it.


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## glen1971 (Oct 10, 2012)

Jlarson said:


> Phase and motor rotation meter.


 Had a guy one job use a motor rotation meter and marked all the motors on how to conenct them.. Unfortunately, he didn't know which way they should spin, so lots were still wrong.. He'd have two banks of aerial coolers with two different markings on each set.. Both did the same function and had the blades all pitched the same.


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## quanchai (Jul 13, 2012)

Rotation Indication


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## magmash (Jul 20, 2012)

Why not just use a Phase Rotation Indicator instead of getting what ever is coupled to the motor damaged from wrong rotation direction ?

Why Bump test and take the risk ?


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## glen1971 (Oct 10, 2012)

magmash said:


> Why not just use a Phase Rotation Indicator instead of getting what ever is coupled to the motor damaged from wrong rotation direction ?
> 
> Why Bump test and take the risk ?


Uncouple.. No risk...


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## quanchai (Jul 13, 2012)

In the Third word they use a Phase sequence protection relay to identify the phase sequence


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