Treadmills That Blow Motor Control Board

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Reggie Reg

New member
Location
Florida
I am helping troubleshoot a gym that has numerous treadmills in it. Too often, the motor controller boards give up the ghost. The mfg recommends a dedicated circuit (hot/neutral/ground) and a 20a bkr for each treadmill receptacle (115V, single phase). Unfortunately, the gym came before the equipment and the receptacle does not have the recommended arrangement (i.e. grounds and neutral are not dedicated to each receptacle only--they tie together before returning to panel) Here are the observations at the three phase panel that feeds the receptacles:

*Neutral current is higher than phase currents
*4% voltage distortion (THD)
*80 - 100% current distortion (THD)

How would the dedicated grounds and neutral help the current and voltage distortion. Any suggestions on plug in devices at the receptacles that could help.
 
catchtwentytwo

catchtwentytwo

Senior Member
Is there any "rhyme or reason" to when they fail. That is, do they fail soon after the first power up or after running for a while. Is there any commonality as to when the failures seem to happen?
 
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Paul Allen

Electrical Contractor
Location
Middleburg Florida
Occupation
Electrical Contractor
Get the information off of the treadmill and call the manufacturer. If their specs call for a dedicated circuit, there may be a reason why. maybe they can give you some insight on things to check, or possibily they have had problems with their circuit boards. If everything looks good on the electrical side, maybe they are having a manufacturing issue if all of the treadmills are of the same manufacture?????

Paul Allen
FL Master Electrician
 
robbietan

robbietan

Senior Member
Location
Antipolo City
Reggie Reg said:
I am helping troubleshoot a gym that has numerous treadmills in it. Too often, the motor controller boards give up the ghost. The mfg recommends a dedicated circuit (hot/neutral/ground) and a 20a bkr for each treadmill receptacle (115V, single phase). Unfortunately, the gym came before the equipment and the receptacle does not have the recommended arrangement (i.e. grounds and neutral are not dedicated to each receptacle only--they tie together before returning to panel) Here are the observations at the three phase panel that feeds the receptacles:

*Neutral current is higher than phase currents
*4% voltage distortion (THD)
*80 - 100% current distortion (THD)

How would the dedicated grounds and neutral help the current and voltage distortion. Any suggestions on plug in devices at the receptacles that could help.
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dedicated grounds no, properly grounded circuits yes. if the boards blow when someone is using it, there may be a problem with their circuits. the 4% voltage THD is below IEEE or IEC recommended standard of 5%, and the current distortion could be inherent for the machine.

a suggestion would be to provide a dedicated feed to the machines so that their harmonics (if any) would not creep up on each other if they are on a single feed. another is to install reactors between the feeds and the machines so you dont have to worry about that high current distortion
 
ghostbuster

ghostbuster

Senior Member
Location
Great White North
With that circuit arrangement,and high neutral currents ,I would expect a large N-G voltage at each treadmill receptacle.Have you measured it?What is the mfr's spec on this and the distortion levels and waveshape(flat topping-reduced peak voltage levels):)
 
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