| Okay, I have a PC repair shop with everything on battery backups. Next door
| is a printer company that recently installed a paper cutter. Just before I
| hear it slam down to cut a ream of paper, my UPS's click and switch over to
| battery for about 1/2 second. I am very uncomfortable about this since the
| power company says they have nothing to do with this. I think the part of
| the problem is this but don't know the technical cure: the power pole drops
| the feed line into a huge breaker box on the back wall. This box has a hug
| ON/OFF lever. From there, about six businesses branch off from that huge
| box. The printer company occupies two office spaces; funny thing is that
| they say they have no problems like mine. There business office section is
| on the east side and my office is on the west side of the paper cutter
| office space.
The power company has everything to do with it. Virtually every power
provider has tariff clauses restricting high motor start currents so
they can ensure power quality to other customers. The solutions they
generally impose when a customer needs that kind of power is to install
the necessary facility upgrade at the expense of the customer with the
| I keep stating to everyone that if all was right, the circuits would be
| isolated and nothing they do with the printer equipment, even improperly,
| should be affecting my 111VAC office circuits.
| Two electricians say this cannot happen a point finger at power company.
As would I.
| Any helpful insights are welcome.
They clearly do not have sufficient transformer capacity feeding these six
businesses to accomodate the special needs of a customer with very high
motor starting loads. One possible solution is to install a separate
transformer and service drop exclusively for the printing company. If
the distribution circuit above that can handle the sudden demand, that
should clear it up, at least for the 5 other businesses. There may still
be an issue within the printing business, but that's for them to take care
of themselves. It might be necessary to have a very large transformer to
handle cutter load _and_
avoid the voltage drop. But isolating things is
usually a cheaper solution, as the existing transformer was apparently
sufficient for the other 5 businesses. Let the printing company have a
transformer to themselves and let them pay for as big a transformer as
they feel they need.
The power company _will_
_always_ tell you it is not their fault and that
there is nothing they can do about it. This is just what they do no matter
what the real issue is (and they very likely have no idea what that issue
is when they say so). You have to keep on them about it. Be sure to talk
to engineering people. Anyone else that tells you they can't let you talk
to engineer people are _unqualified_
to make any claim that the power
company is unable to deal with it.
Ask for some specific information from the power company:
1. What is the available fault current for your service (this information
is necessary for correctly rating circuit breakers so they must provide
it to you).
2. What the is rated "KVA" capacity of the transformer serving your drop.
3. What is the voltage and resistance on the distribution circuit serving
They might be reluctant to give you the information in #2 and #3.
You may need to end up filing a complaint with your local governing agency
that deals with utilities.
Still, some UPSes are more sensitive than others. Try quality name brand
(e.g. actually manufactured by the same company that labels and markets it)
UPSes to be sure.
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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