Normally Closed Contact

K

ksimmons

Member
Location
Mass
Occupation
Electrical Engineer
I am working on including a pushbutton pendant that will include an emergency stop pushbutton. However, the contact configuration for the pushbutton has only a single normally closed and normally open contact. For the circuit design, I am looking for 2 additional normally closed contacts; brings the total to 3 N.C. and 1 N.O.

These 3 N.C. circuits would need to be separate from one another. Would I need to look in a different direction for a pushbutton pendant that could accommodate this or is possible to split both sides of this N.C. contact into 3 individual circuits? My immediate thought is that splitting the circuit would not be possible since it would still just be feeding back to a single contact block, but I am a little unsure.
 
ksimmons said:
I am working on including a pushbutton pendant that will include an emergency stop pushbutton. However, the contact configuration for the pushbutton has only a single normally closed and normally open contact. For the circuit design, I am looking for 2 additional normally closed contacts; brings the total to 3 N.C. and 1 N.O.

These 3 N.C. circuits would need to be separate from one another. Would I need to look in a different direction for a pushbutton pendant that could accommodate this or is possible to split both sides of this N.C. contact into 3 individual circuits? My immediate thought is that splitting the circuit would not be possible since it would still just be feeding back to a single contact block, but I am a little unsure.
Click to expand...
Do you have room to add contact blocks?
 
LarryFine said:
Can you have the single button activate a 3p relay?
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My suggestion is to wire the NC contacts to keep a 3p relay closed, which would keep the safety inherent in NC control circuits.

Wire each contact set in series with, or in place of each circuit's stop button.
 
Jraef said:
Most of the traditional control manufacturers offer buttons with the ability to add whatever contact configuration you want and many layers of blocks.
Click to expand...
But not usually on small hand held pendants. Multiple contacts are common on twi hand 'crane control' style pendants.

Just add a safety relay if you need more Emergency Stop contacts.
 
Use a contactor with the same coil voltage as the load. Break the coil lead and that's your stop. Close the coil lead and that's your start. You can do this with just 2 terminal pushbuttons one normally open, one normally closed.
 
herding_cats said:
Use a contactor with the same coil voltage as the load. Break the coil lead and that's your stop. Close the coil lead and that's your start. You can do this with just 2 terminal pushbuttons one normally open, one normally closed.
Click to expand...
I've done that often especially when my emergency stop had to deactivate several pieces of equipment.
One circuit to a relay or small contactor.
 
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