roller shutter switch

[keniff]

hi guys, i have been asked to swap over a key switch as its damaged, when i opened up the switch its not your typical common with 2 no contacts, it has one NO contact and one NC contact, can anyone explain how it works? im just swapping like for like but just don't understand how it works with the NC side of things, cheers

 

[Sintra]

One side of the switch is open when the other is closed so as the motor will only be signalled to go in one direction at a time.

 

[Andy-1960]

What is the actuator of the switch? 2 position, 3 position, 3 position spring return?
Does it just isolate the door or raise and lower?

 

[keniff]

What is the actuator of the switch? 2 position, 3 position, 3 position spring return?
Does it just isolate the door or raise and lower?

3 position sprung return to centre, used to raise and lower, I was just surprised to see the NC side of things, all the ones I’ve seen have 2 NO contacts, must have some sort of control panel for the shutter?

 

[Lucien Nunes]

I bet it's actually used as 2x N/O contact, but the particular lock cylinder and actuator keeps the N/C switch pressed in most of the time and releases it to close the contact when the key is turned that way. There may have been a cost incentive for them to do it like this as a mechanism with 1x N/O and 1x N/C is standard for single-hole start-stop assemblies.

If you can turn the cylinder you can probably see if this is the case by watching the coloured plastic plunger in the back of the switch, or test it with a meter if it's still electrically intact.

 

[keniff]

ive ordered a new switch, and an extra NO contact just incase!