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Trouble with Change of Transformers for Rectifiers designed in US when used in ASIA

A

anil.deshpande

Jan 1, 1970
0
I have a tape recorder from US whose rectifier takes 30 volts 1amp
which is
realised using 120 volts 60 hz step down transformer.
So I took an Asian Transformer Input 230 volts 50 hz and output is 30
volts 50 hz 1 amp. The transformer is getting heated and sometimes
burn.
What I have observed is if the tape is not running and just connected
to the supply with switch on the socket point of the tape is very hot.
Need help
Thanks
Anil Deshpande
 
P

petrus bitbyter

Jan 1, 1970
0
anil.deshpande said:
I have a tape recorder from US whose rectifier takes 30 volts 1amp
which is
realised using 120 volts 60 hz step down transformer.
So I took an Asian Transformer Input 230 volts 50 hz and output is 30
volts 50 hz 1 amp. The transformer is getting heated and sometimes
burn.
What I have observed is if the tape is not running and just connected
to the supply with switch on the socket point of the tape is very hot.
Need help
Thanks
Anil Deshpande

Anil,

Secudary current of a transformer is usualy specified for continuous load
i.e. a heater or a lamp. A rectifier is all but such a load. It only draws
current peaks at the top of the sines of the voltage. So if you want to draw
1Adc from your bridge rectifier, your transformer should be able to provide
at least 1.4Aac continuous current.

petrus bitbyter
 
C

Clarence

Jan 1, 1970
0
anil.deshpande said:
I have a tape recorder from US whose rectifier takes 30 volts 1amp
which is
realised using 120 volts 60 hz step down transformer.
So I took an Asian Transformer Input 230 volts 50 hz and output is 30
volts 50 hz 1 amp. The transformer is getting heated and sometimes
burn.
What I have observed is if the tape is not running and just connected
to the supply with switch on the socket point of the tape is very hot.
Need help
Thanks
Anil Deshpande

Here lies the problem "Asian Transformer." The design of many replacement
transformers from Asia allow a higher temperature rise, or use as little Iron
as they can get away with without blowing a fuse. If you must use an Asian
Transformer derate it by at least 50%. So for a 1 amp output get a transformer
rated at 1.5 amperes minimum. 2 would be better. However it will still run
very warm. Get a US or EU made transformer and there will be an obvious
difference!
 
J

Jamie

Jan 1, 1970
0
and here lye the problem.
did you measure to make sure 30 volts
at the output of the rectifier is what you
really should get? its possible the
secondary is to high.
you must remember that the voltage
your getting is in RMS. after being
rectified and filterd its going
to be higher.
the Peak is around 42 volts.
you mite want to check this.
 
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