PR54-6 ESP32 Module stopped driving the relay board

I configured the PR16-17-20A for 2 channel bidirectional linear actuator control and linked to the board using the ESP32 BLE module via an app we developed for iOS and Android. It was working well for about 24 hours but then began to fail intermittently. After another 2 hours it stopped working altogether. The device still connects to the phone indicating that the bluetooth link is operational but it will not activate the relays. I have swapped out the relay board and have isolated the problem to the PR54-6. Please advise.


Linear Actuators are inductive loads. Controlling them with mechanical relays provides no protection to the control electronics from the high voltage inductive discharge that is produced when the linear actuator is turned off. Induction is a high voltage discharge created when an electro magnetic field collapses which happens when it is turned off. I would highly recommend installing a capacitor between the relays and the linear actuator to provide some protection to the control electronics. We have an article on this subject here:

It is also highly recommended that you do not share the relay controller’s 12VDC power supply with the inductive load as well if at all possible. If the power supply is to be shared make sure you use a voltage regulator to power the relay controller to clean up those high voltage spikes.