Inductive load

[CHOUAIBOU]

Hi Chouaibou,

After reading up on inductive loads I will surly go with a separate relay, maybe you could answer a question I have. Is it possible to power the relay and motor valves from one power supply and the LogicMachine from an other in order to have as much separation as possible (maybe there is no point to have separate power supplies as the relay needs to have contact with one of LogicMachine output pins)?

Somehow the LogicMachine needs to connect to the relay but I cant see this working if they don’t share the same negative. I can see the relay and the LogicMachine powered by one supply and the valves by an other but would this add any protection to LogicMachine?

If I go with a separate power supply for the valves, would there be anny benefits to go down in voltage? The motors comes in 5, 12, 24VDC?

Joachim

Hi Joachim,
The best practice consists on separate power supplies with their respectives protections (controllers power supply / Loads power supply). If the motors comes in 24 VDC, you can power LM and load with the same 24 VDC main power supply for economic reasons. Thus you will have two lines from the main power supply with their respectives protections (LM 24 VDC power supply line and motor/valve 24VDC power supply line). The relay's contacts (NO or NC) prevent the direct link with the 24 VDC of the LM digital output (DO). They are sharing the same negative but the motor or valve's current doesn't flows through the DO of the LM, but through the relay's dry contacts.

You can also use completly separate power supplies as the command sent by the LM through his DO powers the relay's coil. In this scenario, only the relays's coil shares the negative with the DO of LM. The motor will be powered with the second power supply via the relay's contacts. If the voltage of the motor is different to 24 VDC , this solution based on two separated power supply is the only alternative.

B.R,

Chouaibou.