Searching \ for 'My transformer is pretty hot Why????' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: techref.massmind.org/techref/power.htm?key=transformer
Search entire site for: 'My transformer is pretty hot Why????'.

Truncated match.
PICList Thread
'My transformer is pretty hot Why????'
1999\01\09@235816 by Ricardo Ponte G

flavicon
face
       Hi !!!:


       Some days ago you clear me the doubts about how to connect my transforme
r
with 115 or 220vac.  Ok, I learned the lesson.


       I«m using it in my system (One pic, and four CI more).  I read the cur
rent
that flows out of my power (using the transformer) and it«s about 5mA but
the transformer get pretty hot but It can give me 450mA.

       I have used only One primary to 115vac and connected in series the outpu
t
to get the maximum voltage.

       Is it normal that this device get so hot ????

1999\01\10@101421 by Morgan Olsson

picon face
At 12:02 1999-01-09 -0400, you wrote:
>        Hi !!!:
>
>
>        Some days ago you clear me the doubts about how to connect my
transformer
>with 115 or 220vac.  Ok, I learned the lesson.
>
>
>        I«m using it in my system (One pic, and four CI more).  I read the
current
>that flows out of my power (using the transformer) and it«s about 5mA but
>the transformer get pretty hot but It can give me 450mA.
>
>        I have used only One primary to 115vac and connected in series the
output
>to get the maximum voltage.
>
>        Is it normal that this device get so hot ????

Some small types are barely touchable although running at low load.
This is due to high internal losses, as 50/60Hz is designed for efficiency
in large trafos, generators and motors.

That is one reason switchmode powersupplies are so small and efficient,
working at 30+kHz.

Take care to let air flow to cool it.

I have used a very small 50Hz 240VACprim 0.35VA trafo, and it is almost
the same temperature wether the outpot is open or shorted!

As I expected airflow in the design to be poor, I made a aluminium plate to
press on one side of it to cool it and spread the heat.

/Morgan
       Morgan Olsson                   ph  +46(0)414 70741
       MORGANS REGLERTEKNIK            fax +46(0)414 70331
       H€LLEKS           (in A-Z letters: "HALLEKAS")
       SE-277 35 KIVIK, SWEDEN               spam_OUTmrtTakeThisOuTspaminame.com
___________________________________________________________

1999\01\10@112816 by Mike Keitz

picon face
On Sat, 9 Jan 1999 12:02:24 -0400 Ricardo Ponte G <.....rniniverKILLspamspam@spam@CANTV.NET>
writes:

>        I have used only One primary to 115vac and connected in series
>the outpu=
>t
>to get the maximum voltage.
>

You really should connect both primaries (in parallel) to reduce
resistance losss in the primary.  If the load is less than half of the
transformer's rating though it won't be strictly necessary, though it
will run cooler if you do.  It is OK to connect the secondaries in series
or in parallel to get the voltage you want.  Reemeber that with the
secondaries in series, you have only half the current (but twice the
voltage) that would be developed with them in parallel.

Though you're not doing this, others should beware of using the two
primary windings or two secondary windings seperately to provide seperate
isolated voltage sources.  The breakdown voltage between sections of the
primary or secondary may not be very high.  Usually the transformer is
only rated for isolation between primary and secondary, as it has extra
layers of insulation there.


>        Is it normal that this device get so hot ????

Yes, a lot of small transformers run hot.  They are not designed for
efficiency because the absolute amount of power lost is rather small.  If
the transformer is not way too hot to touch it should be OK.

___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]

1999\01\10@135726 by D. F. Welch

picon face
Caution:
All this is true except You MUST properly phase the
windings you connect in series or parallel.  if you fail to
do this properly the fields will be bucking each other,
the output low and the transformer will get quite hot.

-Dan   W6DFW

At 09:47 AM 1/10/99 -0500, you wrote:
{Quote hidden}

73,
Dan Welch
.....w6dfwKILLspamspam.....qsl.net

1999\01\10@140545 by Brian Aase

flavicon
face
In fact, if the transformer is "perfect", the output will be
exactly zero.  Also it may burn up, unless the primary
DC resistance is very high.

Are you operating on 50 Hz or 60 Hz power?  A cheap..uh..
economical transformer designed for 60 Hz operation only
may saturate at 50 Hz and will accordingly run very hot.

> All this is true except You MUST properly phase the
> windings you connect in series or parallel.  if you fail to
> do this properly the fields will be bucking each other,
> the output low and the transformer will get quite hot.

1999\01\10@182900 by Peter Schultz

flavicon
face
Hi,
Under full load it is very possibile and acceptable to a transformer being
around 70-80 degree Celsius.
Without thermometer you can judge that with your finger if you can hold your
finger on the transformer
only for a short period of time, that going to be around 70-80 degree
Celsius. I would consider this is a normal operating tempreture at full
rated load.
Cheers,
PeterS

1999\01\11@002058 by Russell McMahon

picon face
>From the previous discussions it seems probable that this is meant to
be a 115VAC primary so what you are doing SHOULD be alright.

- What voltage are the secondaries MEANT to give.
Measure each one with an AC voltmeter.
Are the voltages near to the stated values?
They should be.
If they are approximately double the stated values you may still not
have a correct primary connection.

What have you done with the other primary?
It should be open circuit (not connected).
Any unused windings should also be  unconnected to anything.

Presumably no unused windings have their ends connected together.

How hot is "pretty hot"?
Can you keep your hand on it permanently.
If you can keep your hand on it but only very very uncomfortably then
it is about 55 degrees C.
Hotter indicates a definite fault.
Really, with this load, it should be very very cool!!!


regards

           Russell McMahon

{Original Message removed}

1999\01\11@062954 by paulb

flavicon
face
D. F. Welch wrote:

> All this is true except You MUST properly phase the windings you
> connect in series or parallel.  If you fail to do this properly the
> fields will be bucking each other, the output low and the transformer
> will get quite hot.

 Hang on!  For secondaries in series, the first two will be true but
the third does not follow.  Think on it.
--
 Cheers,
       Paul B.

1999\01\11@183824 by J Nagy

flavicon
face
       One common mistake that people make is using a half-wave rectifier
for their supply. This can cause saturation and thus heat like you're
experiencing.

       Jim Nagy
       Elm Electronics
Makers of unique integrated circuits
http://www.elmelectronics.com/

More... (looser matching)
- Last day of these posts
- In 1999 , 2000 only
- Today
- New search...