Selector Switch Hand Off Auto Three Position, four ciruits 2NO/NC

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jermonster

Member
Location
Philippines
Hi,

I need help with the HOA as stated on the subject line. We have an MCC
and we have a local HOA (field) connected to the MCC to control the motor.
We also have a BPCS (like DCS) who can control the motor if the HOA is on Auto position.


Basically, our BPCS needs status from our MCC. When the HOA is in Auto position,
our Auto status should light up. How can I connect the HOA with auto status to MCC,
then MCC to BPCS? Also, what's the diagram for 2NO/2NC HOA with spring return
from left to center, three position, four circuit?
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Hi,

I need help with the HOA as stated on the subject line. We have an MCC
and we have a local HOA (field) connected to the MCC to control the motor.
We also have a BPCS (like DCS) who can control the motor if the HOA is on Auto position.


Basically, our BPCS needs status from our MCC. When the HOA is in Auto position,
our Auto status should light up. How can I connect the HOA with auto status to MCC,
then MCC to BPCS? Also, what's the diagram for 2NO/2NC HOA with spring return
from left to center, three position, four circuit?

BPCS = ??
DCS= ??
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
You do something like this. You can add additional contacts as required. The "PLC" in the diagram is your "BPCS". Typically there would be an arc shown between H (hand) and O (off) with an arrow pointing to O to indicate spring return to Off
 

Smart $

Esteemed Member
Location
Ohio
Personally, I'd wire it using all NO blocks, like this...

MCC%20PLC.gif
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Personally, I'd wire it using all NO blocks, like this...
I have never seen a 3 position selector switch that would let me have a closed contact in hand and second contact closed in auto, unless I used one NO and one NC block. I always use a NO/NC block for that application. One contact is closed in auto and the other in hand and they are both open in off.
 

Rampage_Rick

Senior Member
I have never seen a 3 position selector switch that would let me have a closed contact in hand and second contact closed in auto, unless I used one NO and one NC block. I always use a NO/NC block for that application. One contact is closed in auto and the other in hand and they are both open in off.
Telemecanique/Schneider ZB4 series could do that.
 

Smart $

Esteemed Member
Location
Ohio
I have never seen a 3 position selector switch that would let me have a closed contact in hand and second contact closed in auto, unless I used one NO and one NC block. I always use a NO/NC block for that application. One contact is closed in auto and the other in hand and they are both open in off.
Depends a lot on make/model.

An operator (selector) and an NO/NC block combination with which both contacts are open in the off position is technically a NO/NO block from an overall operation standpoint.

I was surprised to learn some [newer?] designs can have a block mounted in a center position. Refer to page 25 of this catalog: http://www.schneider-electric.com/us/en/download/document/DIA4ED2060507BEN-US?showAsIframe=true
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Depends a lot on make/model.

An operator (selector) and an NO/NC block combination with which both contacts are open in the off position is technically a NO/NO block from an overall operation standpoint.
...
I call the normal state as the state they are in before the contact block is attached to the operator.
 

Smart $

Esteemed Member
Location
Ohio
I call the normal state as the state they are in before the contact block is attached to the operator.
...and that is how they are marketed... but what ultimately matters is their functionality in the assembled state in the OFF position (if there is an OFF position).
 

jermonster

Member
Location
Philippines
Currently, this is my diagram. But I dont know where the 2 NC's will be used. terminal 1 and 3 are for Hand and Auto which are both NO's. How do I use the 2 NC?
1.jpg
 

Smart $

Esteemed Member
Location
Ohio
Currently, this is my diagram. But I dont know where the 2 NC's will be used. terminal 1 and 3 are for Hand and Auto which are both NO's. How do I use the 2 NC?
Your diagram shows 4 x NO.

Being numbered 2 x {1,2,3,4} are these 2 pair NO/NC blocks as described by Don above, in which all contacts are open in the OFF position?

Can't really tell how yours is wired unless we can see the MCC end (perhaps the PLC end also).

If the lower 1 and 3 correlate to H and A, then they'd be the coil side. The other sides (2 and 4) would be connected a) to a PLC contact and b) MCC control L1, respective of H and A.
 

jermonster

Member
Location
Philippines
Here's a good view of the HOA. Basically, terminals in the MCC, say as shown, 1,2,3,4 corresponds to a contact also 1,2,3,4. The other 3 and 4 will be for Auto Status. Now, the box in red (which you can see 4 NOs), are the one Im confused with. We're buying 2NO/2NC three position four circuit HOA. Which of the following (box in red) are NO's, and which should be NC's?
1.jpg
 

Smart $

Esteemed Member
Location
Ohio
Here's a good view of the HOA. Basically, terminals in the MCC, say as shown, 1,2,3,4 corresponds to a contact also 1,2,3,4. The other 3 and 4 will be for Auto Status. Now, the box in red (which you can see 4 NOs), are the one Im confused with. We're buying 2NO/2NC three position four circuit HOA. Which of the following (box in red) are NO's, and which should be NC's?
Not enough info. Goes back to what I said earlier... depends on make/model... and perhaps more importantly the part#. Even knowing that, you'll have to refer to product documentation. Does the drawing specify an exact make/model/pn for the selector switch (i.e. operator and blocks)?

There are e.g. 30mm selector switches which can use the same NO/NC blocks and get different operating configurations by using different operator cams.
 
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