Allen Bradley select switch

[angi]

Hi guys

i have a AB 800T-J20A 3 position spring return select switch, is it possible to build a 3 wire motor control using this switch? that means "Start" by turning the switch to left, release to middle position, "Stop" by turning the switch to right, then release to middle position, i could not find the right contact block used with this switch on AB website.

anybody can help?

Thanks

[ASF]

I can't give you the exact part numbers off the top of my head, but all you need is a switch as you described with a NO contact on the left side, and a NC on the right (i.e. switch activates NO contact when you turn it left, and NC contact when you turn it right). Then it's no different to a NO start button and a NC stop button, and you just wire them up like any other start/stop circuit

[benaiahhenry]

There are several different contact options for that switch, but the most common are probably the "Shallow Block Contacts" 800T-X series.

To answer your other questions I think you'll need to provide a little more information...what is the switch wired into? A drive? A PLC? etc...

-Benaiah

[angi]

thanks guys.
i just need to control a starter.
in the beginning, i think it is not difficult to do it just like ASF mentioned, i found 800T-XD1(NC) and 800T-XD2(NO) contact on AB website, but when i talk to AB support, they told me that would not work.

[ASF]

Originally Posted by angi

thanks guys.
i just need to control a starter.
in the beginning, i think it is not difficult to do it just like ASF mentioned, i found 800T-XD1(NC) and 800T-XD2(NO) contact on AB website, but when i talk to AB support, they told me that would not work.

Maybe you gave them too much information and confused them

As long as your switch operates one contact when you switch it one way, and another contact when you switch it the other, all you need then is for one of those contacts to be NO and one to be NC. Most two position switches operate both contacts at the same time, but I've never seen a 3 position switch that did that.

[ASF]

Just ask them for a single NC contact that can be piggybacked onto your existing block. (perhaps an 800TC-XD2). The 800T-J20A has a NO contact on each side it switches. So your NO contact for the "start" direction is already taken care of, you just need to piggyback a NC contact onto the other side to use as your "stop" contact.

[Bit_Bucket_07]

Originally Posted by ASF

Maybe you gave them too much information and confused them

As long as your switch operates one contact when you switch it one way, and another contact when you switch it the other, all you need then is for one of those contacts to be NO and one to be NC. Most two position switches operate both contacts at the same time, but I've never seen a 3 position switch that did that.

It is possible to get an oddball cam on a 3 position selector switch, but that part# wouldn't indicate one.

[angi]

ASF

you and me on the same page, this what i am going to try, i do not know why the support think J20A will not work in this way.

[ASF]

I find that I have to be very careful they way I phrase my questions to my local AB agents. Dumb it down as much as possible and restrict it it only the critical thing you need to know, which in this case, is "what NC contact can I piggyback onto my 800T-J20A". Remember, most of the time they're a salesman and nothing more, you go asking too many in depth questions and they'll just tell you "no" because they don't understand and don't want to be responsible for selling you something that they don't know will do what you're asking.

[blackandredwarrior]

"oddball cam" I think that sounds right.

You need a cam that would all for the NO contact (start position) to close while the NC (stop) position stays closed. Note that you may not using the NO or NC contacts that you think you would use.

See page 10-14 for the cam key.

http://literature.rockwellautomation...a911_-en-p.pdf

I'm wondering if a standard cam and a NO/NC combo block on white would do what you want. Left would close the NO, but the NC should stay closed.

I usually get out them out and start playing with them. Just need to make sure that nothing (the NC in the stop circuit)
drops in the transition from left to center.

[angi]

the contact block on J20A is 800T-XA, there are four terminals, when you turn the switch to left, two terminals at the top will be connected together, when you turn the switch to right, bottom two terminals will be connect together, when the switch in middle position, no switch connected.

[ASF]

Yep. So it's just the standard terminal block with 2 NO's on it. It should also have two hols in the plastic case which expose a surface that moves up and down as you turn the switch - you should have one move up and down as you turn the switch one way, and the other move up and down as you turn it the other. All you need is an NC to piggyback off one side of it, the piggyback contact's plunger will protrude into that hole and be actuated by the surface moving up and down

[angi]

how to understand CAM, i am using 800T-XA, if i select KB7 cam X O O, what this means?

[angi]

what is the difference between KB7 and KC7?

[ASF]

X = closed, O = Open. The three letters refer to the three positions of the switch from Left to Right. So you need a cam that has one channel O O X, and one X X O. The O O X means that the contact is closed only when you turn it left, and the X X O means that the contact is closed when you turn it left, closed in the centre, and open when you turn it to the right