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transformer getting hot

 
 
donzxn
 
Reply Mon 14 Sep, 2015 11:18 pm
i use a 12 0 12 500ma transformer for automatic water level controller using 555.but the transformer gets hot.the current drawn by the circuit is about 60mA.how can i reduce transformer heat problem.?
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Type: Question • Score: 3 • Views: 861 • Replies: 12
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Wilso
 
  1  
Reply Tue 15 Sep, 2015 04:33 am
Ok, I didn't understand most of that sentence. Want to try again?
donzxn
 
  1  
Reply Tue 15 Sep, 2015 05:59 am
@Wilso,
ok ..
i have built an automatic water level controller circuit using 555 using it in bistable mode.I am using a 12 0 12 V 500 mA transformer in this circuit.But the transformer got too hot.The current drawn by the circuit is 60mA. what can i do to cool down the transformer?what may be the probable reason?
Ragman
 
  1  
Reply Tue 15 Sep, 2015 06:14 am
@donzxn,
I'd hate to suggest something as simple as use of a muffin fan and better ventilating.

Are you sure that your reading the current accurately?

There's something that is making it inefficient. I don't know the engineering of the circuit but maybe it's the frequency that the 555 chip is being run?
Perhaps the transformer needs replacing with a larger value. Is there a feedback issue that might be improved?
timur
 
  1  
Reply Tue 15 Sep, 2015 06:27 am
@Ragman,
There is something wrong with the circuit.

Typical power consumption of a NE555 is 3mA.
Max output current is 200 mA.

The transformer? (power supply) shouldn't be hot at the max values.

I'd suggest donzxn provide more details about the transformer/power supply and the drawing of the circuit.
Leadfoot
 
  2  
Reply Tue 15 Sep, 2015 06:40 am
@donzxn,
Maybe you are expecting it to be cooler than transformers usually run. How hot is 'hot'?

If it really is too hot and there is no wiring error, the transformer may be bad.
Leadfoot
 
  1  
Reply Tue 15 Sep, 2015 07:11 am
@Leadfoot,
To test the bad transformer theory, disconnect the secondary connections and power up the primary. If it still gets too hot, it's bad. Normal eddy current losses in the core will make it warm but not hot. If it runs normally after disconnecting the secondary, there is a wiring or component problem in the circuit.
donzxn
 
  1  
Reply Tue 15 Sep, 2015 08:03 am
@Leadfoot,
i have tried the test.but it still hot enough.But my problem is that i have buy 7 transformer of that type.but all of them give the same problem.
timur
 
  1  
Reply Tue 15 Sep, 2015 08:05 am
@donzxn,
What transformer is that?
donzxn
 
  1  
Reply Tue 15 Sep, 2015 08:08 am
@timur,
i have used a relay of 12 v and 6 LEDs for indication.that is why the current drawn by the circuit is more. and the transformer is of 12 0 12V center tapped 500mA.
Moreover with no load the transformer gets also hot.
0 Replies
 
donzxn
 
  1  
Reply Tue 15 Sep, 2015 08:10 am
@timur,
oswal.
0 Replies
 
donzxn
 
  1  
Reply Tue 15 Sep, 2015 08:13 am
@Leadfoot,
how hot means it is difficult to touch for long after 30mins with no load(secondary open).
I have to use the transformer for 24×7 for my circuit(automatic water level controller).Is there any way to cool the transformer,so that the whole circuit will not burn out?
Leadfoot
 
  1  
Reply Tue 15 Sep, 2015 08:24 am
@donzxn,
Sounds like a poor quality transformer design (high core losses). I hate throwing out purchased parts too but I think you need to source a better transformer if the heat bothers you. If it gets too hot to hold with just convection cooling, it's a POS.
0 Replies
 
 

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