I am currently installing 2 systems of enveloping machines in Canada.The systems were designed and built in Switzerland where the frequency of the 3 ph powere is 50 hz. I am finding that the screens that are scsi controlled touch screens, are glitching (horizontal lines) when used on a 60 hz power system (canada). The screens are controlled thru an industrial PC with a standard 100-240 vac 50-60 hz PSU. I also have a problem with the software crashing out into the dos prompt for no apparent reason. Does the SCSI screen have any components that would be specific to it running on a 50Hz system, or is all the timing taken from an internal time base on the SCSI interface card, any ideas????????
I am a lone Englishman in a sea of Canadians wanting my head on a platter......

 

I would not jump and blame the problem on the 50 Hz / 60 Hz thing right away. Is the power in the plant clean? Is your earth-ground clean? Perhaps hanging a power line monitor on the system (just for a few days to see what is happening) or using a good isolating transformer (all the time -- you probably already have one) is a good idea. Perhaps even putting the HMIs / SCADAs on a UPS or UBS would help too.

What do the gents from Switzerland say -- have they seen these crashes
too?

Are the touch-screens TFT or do they use a conventional picture tube?
Perhaps this might help other users who may have seen something.

In this age of a global market, I get sceptical when someone blames power
frequency.

Just some thoughts, anyway.

If all else fails, you could always go to one of those cheesy travel
catalogues and purchase an AC-DC-AC converter that does 60 Hz to 50 Hz!

Don't worry too much about being English -- many are descended from Redcoats
here in the far North.

 

Normally this can work but whether or not you will get field frequency
interference depends on the quality of the screen. I don't know about line
voltages in Canada but you might also be having problems with voltage
settings, many PSUs can cope with all the different voltage and frequency
standards and some can't, sometimes there is a voltage selector on the back
of the PSU to select the Voltage. That might help with the computer crashes.

The easiest way to correct all this is to get a type 3 (always on line) 50Hz
UPS with the correct voltage rating to match the components and hook the
computer gear up to that.

Also be aware that if the voltage and frequency rating of the 3 phase
components (Especially motors) is wrong they wont run at the correct speed.
If used Direct-on-line, motors in particular might overheat due to increased
current load because of a low supply voltage. This can be overcome with a
suitably rated Variable Frequency Drive.

Bob

 

If this issue is intermittent the problem is most likely related to Harmonics
If it is constant, there is probably a lot of magnetic flux.

The first problem is typically related to an IGBT or IGCT, "VFD-Variable Frequency Drive" Shut one drive off at a time; you should easily be able to isolate the VFD that is causing this problem, I know of one drive that is made in Germany that causes this problem.

The second problem is typically old style type P ballasts used on fluorescent lighting, shut the lights of and see what happens!

Good luck.