How to build overcurrent, overvoltage, and reverse polarity protection circuit

nur hidayah's picture


Joined: Aug 16, 2019

Replies: 0
How to build overcurrent, overvoltage, and reverse polarity protection circuit
August 16, 2019 - 12:27pm


Hello All... We need inputs from you on how to build overcurrent/overvoltage protection circuit between chiller and it's controller. Because we sometimes encountered that when chiller gets faulty during running it also damages the controller, or vice-versa. We want to put protection between controller and chiller the avoid damaging each other. The image shown is the wiring between controller and chiller. Really appreciate any inputs. Thanks.

Hiro_Hamada's picture


Joined: Apr 17, 2018

Replies: 120
Protection circuits
August 17, 2019 - 1:31pm

It is not possible to tell exactly what type of protection should be used without knowing the actual numbers. Like the operating voltage and operating current. But Iwill guide you to relevent pages from where you should be able to design the circuit required for your application

Reverse Polarity Protection:

The most crude way of reverse polarity portection is byusing a Schottky diode in series, but since you are operating on high voltage a MOSET protection circuit should ideally do the trick. The link for the sameis given below

You can also read through this forum link to understand other type of possible circuits


Overcurrent Protection:

For overcurrent protection a FUSE should work. Just find the current rating (also consider peak current) of your Chiller and add a fuse in series to the power line. Normally the fuse value should be 25% more than the actual current value. If you are looking for short circuit protection you can look into the Crowbar Circuit which again uses a fuse. This circuit just blows off the fuse when short circuit is detected protecting the chiller from getting damaged. 


Overvoltage Protection:

For over voltage protection you can use a voltage protection circuit like this Again you might have to modify it based on the voltage rating of your chiller.


Normally an Ideal controller for the chiller should already have these protection features you are asking for. If you are facing these strange voltage and current outputs its recommended to replace or upgrade to a better controller.