I have 2 units in a school hallway, running seperate rooms, that are blowing
transformers. I have already replaced one transformer, only to have it blow again
within a half hour. The units are on seperate circuits, not connected in any way.
Does anyone have any idea what could cause this?
Thank's for the replies. I only have about an hour
to spend on this in the morning, and was hoping there was
a common problem that I couln't see. The units are only 3
or 4 years old, worked fine all summer, and I assume worked
in heating for a month or so.
On 12/2/2010 8:51 PM, email@example.com wrote:
In the morning, if I can walk, I have to go to a customer's store to
repair network cable that mice chewed up. For some reason, the little
critters love to chew on plastic insulation. Did you install new
transformers with same current rating? Somewhere on the transformer
there will be a label or printing indicating the VA rating. 40VA is a
popular size but in a school or institution the low voltage may run
electrically operated dampers and /or valves. You would need a
transformer with a higher current rating.
On 12/2/2010 9:51 PM, firstname.lastname@example.org wrote:
Do you have a DMM with a 10amp shunt for measuring current? A larger
transformer might burn up the low voltage wiring. I would suggest
taking the 75VA transformer and putting a 5amp fuse in line with the
low voltage so you can check the current draw. The 75VA unit may have
a built in circuit breaker from the factory. Of course check the voltage
going into the transformer because some goofy electrician
may have hooked that line to a higher voltage. Sometimes it's the
simplest thing that's causing a problem.
The 75VA does have its own breaker. I'll try that in the morning just to
get them some heat. Any ideas what I should be looking for as to what
could cause this? It would be a pretty huge coincidence, the way they
On 12/2/2010 10:41 PM, email@example.com wrote:
A critter could have chewed up some wires or the input voltage is too
high. If you have three phase power with a high leg, someone might have
moved the circuit breaker that supplies power to the transformers to a
high leg. I assume the transformers were hooked to a 120VAC supply or in
the case of a business or institutions, the transformers may require
208-240VAC supply connected to the proper pair of wires on a
multi-voltage input control transformer. Always check the basics and
don't assume you have the correct power going to something. The
your friend. The first thing I would do is to check all voltages without
the air handler controls being hooked up, if those readings are proper,
start checking current draw for the control system. A lot of control
transformers have separate 208 and 240VAC connections. If your supply
is 240VAC and you connect the 208VAC winding, you can possibly let all
the magic smoke escape from the transformer because you will get a lot
higher secondary voltage than 24VAC. :-)
I have one question for you? You said that you replace transformer
have try or bother checking amperage in and out
Then perhaps you question maybe some what legit???
Even so it does not make sense for me asking these but what the heck!!
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