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Discussion Starter · #1 ·
Is there a reasonably priced device to protect a machine from running in the wrong direction due to changeing of the three phase supply.

I ask becuase I will be installing 2 $60K compressors that can incur a LOT of damage if they are turning the wrong direction for any length of time.

They will be on a military base with a contractor that manages the power distribution. I have seen instantaces of rotation being changed in a building after work is done. Also sometimes they will hook up a generator to supply wrong rotation.

Preferable would be a switch that can interupt either the control power or the loop of the magnetic starter. Optional would be a big red flashing light that says DANGER WRONG ROTATION below it.

I know I could make a switch to interupt control or closing coil ckt but it would not look slick and proper. It would also probably take a lot of time and $.


Cheers, jim
 

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Discussion Starter · #3 ·
THANKS. That is exactly what I had envisioned. I am going to send the link to the compressor mfr and request it to be built in. That way there is no question of me modifying there equipment and voiding the warranty.
 

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The shop I worked in had the services changed one day and the electrician says "your motors may spin backwards". I didn't think much of it until I went to open the overhead door and it crimped the door and bent the metal arm that connects to the opener.
 

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That relay is really neat. I ran a mfg plant for 8 yrs and monitored a good bit of machine and process equip installs.

Given the example of the roll up door above --- how would you check the phasing after some work has been done to see if its ok ? You have to bump a motor or what ?
 

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That relay is really neat. I ran a mfg plant for 8 yrs and monitored a good bit of machine and process equip installs.

Given the example of the roll up door above --- how would you check the phasing after some work has been done to see if its ok ? You have to bump a motor or what ?
I have a really simple rotation meter.
 

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That relay is really neat. I ran a mfg plant for 8 yrs and monitored a good bit of machine and process equip installs.

Given the example of the roll up door above --- how would you check the phasing after some work has been done to see if its ok ? You have to bump a motor or what ?
Starting the door halfway open is a simple way, just see which way it goes.

You could also give it a quick run with the drive belt or chain removed.
 

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Discussion Starter · #9 ·
Starting the door halfway open is a simple way, just see which way it goes.

You could also give it a quick run with the drive belt or chain removed.
definatly but you have to be aware that there may have been a change and also which equipment needs checking. Plus get to that equipment before someone starts it.

I figure with this affordable relay installed I will get the call "Jim our compressor is broke" and I can "fix it" by swapping two input phases. No damage done.
 
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