Power quality issue

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JdoubleU

Senior Member
We are having problems with our running machines in the rec center. They are the kind with the tv screens on them. The screens shut down on errors that cannont be traced. The company is thinking it is a result of problems with our AC power. We have had a power quality meter metering the panel that runs nothing but exercise equipment for about 5 days now. There has only been one event. The duration of this event only lasted 0:00:00:067. The event is a voltage dip to 72.4 volt on a 120 volt on phase C. Can anyone help me with any ideas what would cause this? And would this be what is causing the problems with the machines?
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
We have had a power quality meter metering the panel that runs nothing but exercise equipment for about 5 days now.

The manufacturer will always blame you, the customer.

Are you measuring harmonics and swells/sags? I am surprised by how often these are not included as part of PQ measurements.
Are you performing measurements with the running equipment turned off or unplugged?

This equipment most likely has variable speed (e.g. servo) motor control in them. They will be a major source of harmonics especially when viewed individually, however you hope there will be some cancellation at the common panelboard.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
the 'tech support" guys you talk to on the phone often blame things on "bad" power or "bad" grounds.

the reality is that a lot of times equipment is not well designed to deal with the normal idiosyncrasies of the power grid. there is not a whole lot you can do if this is the problem other than power conditioning of some sort.
 
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