computers sensitive to voltage

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readydave8

readydave8

re member
Location
Clarkesville, Georgia
Occupation
electrician
I don't know enough about this to ask intelligent questions but:

small embroidery operation with 36 machines, each has computer

they think they are having too many computers replaced, service tech says they need 120-121 volts to be reliable, and the 117-118 v present are causing problems

is it likely that low voltage is causing problems?
 
That shouldn't be an issue. The switching power supplies in most computers can take some variance. Three volts low isn't an issue.

How old are the computers that are failing? And is there surge protection at each computer?
 
Computers don’t run on AC power. They run on DC.
Usually 3.3VDC, 5VDC, and 12VDC for the fan..
The power supply works fine in a range from 90VAC to 135VAC.
 
We'd need to know more about the specifics of the failures. Why are they replaced? Is it power supplies, I/O cards, or what?

Tell them to add a good UPS to one computer, and a good surge protector to another, and see whether that affects anything.

Sharing circuits with motorized machines is more likely to cause issues than a slight (and this is very slight) voltage variation.
 
Also, we have purchased 3 embroidery machines over the years. There is a HUGE range of quality between different brands. Some are just a hodge podge of parts from here and there, and some are real good quality and will run years. For all the trouble we have had w/ our earlier machines, never needed a computer.
 
readydave8 said:
they think they are having too many computers replaced, service tech says they need 120-121 volts to be reliable, and the 117-118 v present are causing problems
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Complete BS. Modern generic computers will run on almost anything from maybe 100 to 260 although they may have a 120/240 switch on the PS; I've seen some servers running merry along on around 90v.

Could be getting zapped by surges, could be having problems because something else is causing a momentary sag. Either way, they ought to be on UPSs anyway.

We'd really need to know what parts are failing (and maybe even the mfg/model of the machines). Could be that the machines themselves can't handle a voltage sag and take it out on the computers, too.
 
As others have implied, service tech is uninformed, poorly trained, or even incompetent.
Service tech for who, the emb. machine vendor, computer distributor, whose dollar is involved ??

Put a scope on the line to know what your power looks like. In early 80s, big aerospace company here installed many computers in a certain building served by a few 500 kVA delta-Y transformer.

1st warm day a transformer smoked. Old 1980s computers did not have PFC 85-260V power supplys, just full wave bridges and caps, lotsa triplets short circuit in delta primary.
Computer power supplies these days all have PFC front ends so near zero rectifier generated harmonics, esp if rated 120/240.

My 2 cents off the wall re. embroidery machines - educate the operators to not have fabric draped over the computers or relocate the computers so that airflow does not get blocked and computers fail from overheat.
 
PS: - so do folks at that small factory, or the tech, realize there is a screen on computer fans that can become clogged with lint, esp in a fabric rich environment? can you say overheat?
 
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