# Phase error



## CdotJdot (Nov 19, 2011)

Good morning folks I am a maintenance electrician at an injection molding facility and we just installed a brand new injection molding press that use 750 volt dc servo motors to drive the hydraulic pumps these motors are controlled by B&R drives. The new machine has auxiliary 480 volt receptacles built in to run our mold temp controllers which are basically water pumps with heating elements and dump valves to control the water temp being pumped through the molds. Now on these temp controllers there is a phase monitoring system to insure the correct rotation of the motor and when we have them connected to the machines auxiliary outlets and the servo pumps are running we will get a phase error on the temp controller but if we plug the controllers into a power source not connected to the press everything is fine and dandy. Has anybody seen somthing like this before, or could anyone explain to me their theory, any feedback would be great thank you


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## CdotJdot (Nov 19, 2011)

Forgot to add I've tried switching leads and still get phase error and all voltage readings and connections and rotations are good


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## backstay (Feb 3, 2011)

I there noise from the drives backfeeding the 480? Maybe the controllers are seeing that.


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## CdotJdot (Nov 19, 2011)

That's all I could think of is there any way to eliminate that if that's the case


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## backstay (Feb 3, 2011)

CdotJdot said:


> That's all I could think of is there any way to eliminate that if that's the case


Some type of filters or isolation trany. I'd put a scope on the controllers both ways to see if there is noise.


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## John Valdes (May 17, 2007)

Each servo motor should have an encoder or resolver attached to its shaft.
This is how the machine knows which direction these servo motors are turning.
Is it possible the encode signal is backwards? Reversed?
I mean this could be a polarity issue with one or more servo feedback devices?

I'm not exactly sure about your question. But can assure you a feedback device tells the drive in what direction the motors turn.
You may have to swap the feedback wires?


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## CdotJdot (Nov 19, 2011)

Thank you for your reply John but I am not having trouble with the servo motors themselves I'm having trouble with the mold temp controllers which have a regular 480 volt 3 phase motor controlled by just a motor contactor, but when these mold temp controllers are plugged into the 480 volt auxiliary equipmemt receptacles on the press I get intermittent phase errors


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## CdotJdot (Nov 19, 2011)

On the controllers


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## John Valdes (May 17, 2007)

Have you verified the phasing is the same from both sources?


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## Wirenuting (Sep 12, 2010)

Did you check input rotation with a meter?


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## JRaef (Mar 23, 2009)

Is this by chance a machine made overseas, and the 480V 60Hz aux power to the outlets on the machine is being created by an inverter because the machine was really designed for 380V 50Hz? 

Because if so, that might explain why your external devices are indicating a phase error. They are looking for a standard sine wave power input, and you are giving them a PWM pseudo-sine wave from the inverter. When you connect them to your other "real" sources, they are seeing what they were designed to look for.


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## RePhase277 (Feb 5, 2008)

Be sure you're getting all three phases at the 480 receptacles.


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## Chrismcd (Apr 9, 2014)

Is the phase monitoring relay phasing incorrect? This would throw an error if everything else is ok... Or you could have a bad connection to the motor or the relay i'd check all these. Also id check all the fusing it could be as simple as bad fuse. 

Sent from my LG-D852 using Tapatalk


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