I run a Toshiba Digital copier machine in my shop and the machine started showing error codes related to power issues a few days ago. This happens randomly during daytime. There were no problems at night time. So I have transported my copier machine to an another place during the daytime and used it for a long time with no errors reported. I have concluded that there is harmonic distortion in the power lines of my shop area. Also, I have noted that there is a workshop near me which uses heavy AC motors. I suspect that they cause the issue in the power lines because of malfunctioning equipment.

Is there any circuit that can filter these harmonics which I can build? Will using a UPS fix the problem?

I have already complained about this to the power company but there seems to be no action taken by them.


closed as off-topic by PlasmaHH, RoyC, Dmitry Grigoryev, awjlogan, Chris Stratton Oct 12 '18 at 4:39

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  • \$\begingroup\$ Try a computer type power strip with filters. \$\endgroup\$ – RoyC Sep 27 '18 at 8:58

You should complain to the authorities, that a distribution company sells you an inadequate power supply. Probably you would need to hire a qualified company with network analalyzer and logger.

Other possibilies are to install an EMI filter, but this will partially resolve the problem.

It is not related only to the harmonics, rather high frequency disturbances caused by inverters, phase angle switchers, ... all those devices need an EMI filter installed or generally one filter bank at the distrubtion site in the factory. For economic puprposes, many of them install equpment without filters ans so they violate the contract.

There are many filters available, but they are big, bulky and designed to be mounted in electrical cabinets. It is intended to be installed at the source of the noise emission and not viceversa, as you would need it.

Shaffner filter

  • \$\begingroup\$ I understand that this is not an issue with my side so I cannot do much about it. But I need some quick fix because I need to run this machine. After some study about EMI filters I have decided to use an EMI filter from a computer power supply. I have seen most of the SMPS are protected with EMI filters but seems to be power supply of my machine missing it. I'll update the results too. \$\endgroup\$ – Anuradha Sep 27 '18 at 9:25
  • \$\begingroup\$ They are not protected by, they have a built in filter to block emiting noise into the network. It's right the opposite. SMPS generates noise, to block this a filter is applied. Since your device doesn't generate noise it has no filter. \$\endgroup\$ – Marko Buršič Sep 27 '18 at 9:34
  • \$\begingroup\$ Yes I have figured that out a moment later. So itn't there anything I can do on my side? \$\endgroup\$ – Anuradha Sep 27 '18 at 9:37
  • \$\begingroup\$ @Anuradha Mount the filter anyway, it will attenuate the noise also in opposite direction, this is the best you can do. \$\endgroup\$ – Marko Buršič Sep 27 '18 at 9:40
  • \$\begingroup\$ OK. I'll try it. \$\endgroup\$ – Anuradha Sep 27 '18 at 9:41

This is clearly any industrial conducted and possibly radiated EMC issue if the unit has a floating SMPS without earth ground, e.g. DC plug.

The solutions may require a properly designed CLC CM and DM "Pi" filter with CM and DM chokes and RF X caps and Y caps to earth for rated current and if laser must withstand the heater current rating.

If earth bonding of Y caps is essential. Also the USB cable if used to host device and its earth bonding is also critical

I found this out yesterday at a Uni EE POwer Lab when a tower could not even communicate to an Arduino on a USB cable with decent 12V SMPS to Arduino with linear regulator for 5V. One fix was made both ends (host and client) floating, e.g. laptop to Arduino next fix is earth bond Arduino CNC target and Arduino 0Vdc and then all stray local noise is shunted to earth. THen if host noise also conducts earth bonded ground noise an extra line filter is needed.

Caution CLC CM filter cascaded line PI filter can cause anti-resonant issues so ask a professional to design it for DM and CM mode or trial and error. Your choice. Verify design with earth bonded 10:1 (calibrated with step pulse AND AC Line to both probes for flat line) probes in A-B mode AC coupled with short gnd clips. If you don't know what a CLC line filter does, then you cannot design it.

  • \$\begingroup\$ Alright the issue has been fixed now. The power company disconnected the supply to that workshop today morning until they fix their equipment. Problem is solved now. Anyway your answer has pointed out me importance about grounding. I have found the building does not have a properly grounded power line. It wasn't a problem until this harmonics issue. Anyway I'll leave this thread unanswered as it may helpful for any others has some issues like this. \$\endgroup\$ – Anuradha Sep 28 '18 at 5:47

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