3 position switch-- do I have this right?

Is this how things work with the three position, maintained switch?

When switch is turned to the left, it activates the contact block on the left. Its normal state then changes. So NO ---> closed activating the coil of my contactor.

If turned to the right, it activates the contact block on the right. So with another NO contact block... NO---> closed activating the coil of my other contactor.

When in the middle, neither is activated. So both NO contact blocks are open and no devices are active.

Correct?

That's all I need to know, really. But I am curious what happens when you stack contact blocks. Does it just change the state for both stacked contact blocks?

Cheers an thanks.

With 2 layers of contacts you are doing the same thing but adding extra functionality. I'm sure there are other ways, but here is my particular use case, BCS is my auto controlling device. Three position, left/auto center/off right/manual. The switch activates one contact block via the bottom layer and controls the SSR manually or automatically with the next level of blocks. Example in my pic, the bottom layer you are always closing the hot side of the 120 circuit left or right of the three position switch. This activates the contactor coil so it's on and allows the high voltage to pass through. Then on the next layer you are controlling the SSR which is controling one hot leg of the 220. Notice on the top layer the white is on both sides (goes to the SSR). When you go to the auto side it closes with the red wire which goes to the BCS controller which then can turn the SSR on and off as programed, rapid switching (auto mode). To the other side 5v constant is applied constant which when closed with the same white wire will make the SSR stay on all the time (manual mode).

Does that make sense?



Bunch of pics here where it may be easier to see the wire runs a little better.
http://mateomtb.smugmug.com/Category/Brewery-Build-1/21474238_CF45Ww#!i=1958273806&k=LmbSTHr

Dgonza9 said:

Is this how things work with the three position, maintained switch?

When switch is turned to the left, it activates the contact block on the left. Its normal state then changes. So NO ---> closed activating the coil of my contactor.

If turned to the right, it activates the contact block on the right. So with another NO contact block... NO---> closed activating the coil of my other contactor.

When in the middle, neither is activated. So both NO contact blocks are open and no devices are active.

Correct?

That's all I need to know, really. But I am curious what happens when you stack contact blocks. Does it just change the state for both stacked contact blocks?

Cheers an thanks.

Click to expand...

Correct.
I have a three way switch in my panel. The first "layer" is normally open contacts for choosing between two different heating elements. The center position being off for both elements. The second "layer" is normally closed contacts. It is used in the interlock circuit that prevents the control panel from being powered up if all selector switches are not switched to off.