Short circuit protection

[raivo]

I have 220V 800W toroidal tranformer. Output is 36V. I want to use this for various experiments. I wish that it would be impossible to ruin transformer by accidental short circuit or overcurrent. I think of powering the transformer through relay and wiring some analog circuitry that detects voltage peaks on current sense resistor and switches power off if some threshold is reached. Is this reliable or maybe i need especially fast circuitry for this? Are there easyer ways to reach this goal?

 

[BEPC13]

Why don't you just use a fuse on the primary side of the transformer. 800 Watts at 220 V works out to be about 3.5 amps. Maybe the circuit design and building is a achedemic exercise for you which is fine. But when you start looking at the time and cost involved in the circuit I think the fuses have merit. They are fast, reliable, and fairly inexpensive. I wouldn't think you are going to be overloading this tranformer during every experiment so a box of 10 should last quite a while.

 

[electestmaintain]

1)What is the primary Voltage? 220 Volts or 36 volts?
2) Where do you expect the short circuit? The torroid is not going to be affected with primary side short circuit. Secondary short circuit you can limit the current by selecting proper guage winding wire. In any case primary fuse is always good for protection.
3) Where do you want to detect the Voltage peaks? 36 volts side or 220 Volts side.
4) I agree with the contributor primary fise should take care of protection. Even glass fuse should be ok.
5) What is the load on secondary 36 Volts.
6) why are you consdering relay and contacts?.
Marvin

 

[raivo]

Thanks for help! Primary voltage is 220V and i talk about short circuits on secondary. I think its easyer do detect voltage on secondary because voltage is lower there and more acceptable to IC-s. Relay was considered beacause it makes easyer and faster to recover from short circuits. I also was not sure how reliable protection cheap fuse really is. I plan to use different resistive loads on secondary such as nickel-chrome wire or voltaic arc.