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Impedance of a Relay
The security system of a belt conveyor must have emergency keys. I have a question about the impedance of the security relay in this situation.

I am desigining a security system for a belt conveyor, and I'm using two-way pull cords. These pull cords will be connecting in 24Vcc. The signal will be sent to a box where I'll make series connection among them, and after that, the signal will be send for a PLC. There will be a security relay in this path, and I wanna know the impedance of this relay can to affect my signal, and how can I design this? If you have a reference to tell me, or explain how to do this calculation, I'll e very grateful.

my email is:


When you say relay in series, are you describing the coil or the contacts?

it all depends if your shut down is a hardwired redundant shutdown, with the plc function separate. or is it all coming through the plc?