An inductive load is any load that can hold a charge, such as a solenoid, electromechanical solenoid, door strike, etc. When the load is turned off, that stored charge must go somewhere. If you’re using a relay device with an inductive load, the inductive charge likely will end up arcing across the contacts. This can lead to shortened relay contact life or other issues.
Inductive kickback can be resolved by adding a component to dissipate the stored charge. To protect your ControlByWeb® relay device, you can install one of the following:
- A reverse biased diode, or a “flyback diode” for DC voltages.
- An RC snubber circuit or device. This includes a resistor and capacitor to dissipate the charge safely.
- An MOV (Metal Oxide Varistor), rated for double the voltage used to control the load.
- A TVS diode, rated for double the voltage used to control the load.
Install these across the coil or load (preferred) or across the ControlByWeb device’s relay contacts. Installing one of the above components to aid in mitigating inductive kickback is a best practice that will prolong the service life of the relay contacts in your ControlByWeb products.
A wiring example showing an MOV in use across a high-current relay coil.
Some ControlByWeb models are sensitive to inductive kickback which can cause undesired behavior. These include:
- X-WR-4R3-I and -E modules (V11.0 Rev J)
- X-WR-1R12 (V11.0 Rev J)
- All X-WR-444 and X-WR-441 variations
- X-401
When an inductive load is controlled on one of the above modules, network connectivity on the ControlByWeb device may be lost and a power cycle may be necessary to restore network connectivity. Using one of the methods to mitigate inductive kickback will lead to a longer service life and resolve undesired behavior.
If the above suggestions aren’t working for you, please reach out to our technical support team and they will be happy to help resolve any issues.