Square D lighting contactor wiring diagram

[kwired]

As used in your application the relays are likely nothing more then an interfacing device to be able to use a class 2 circuit for the bulk of the control wiring. Your problem doesn't appear to be located in the 120 volt portion of the control circuit but rather in the 24 volt portion of the control circuit. You have either have a stuck contact in one of the relays or more likely a constant 24 volt signal to the coil that is maintaining output contact position. This could be a stuck pushbutton, pinched cable causing short between conductors, miswired switch or other miswired connections.

Most likely one relay initiates a latch signal and the other an unlatch signal to the lighting contactor, but each has a 24 volt switching scheme somehow driving it, may be manual switches, automatic switching devices, or combinations of both.

 

[gar]

151027-2155 EDT

Wire 2 Race:

What is a relay? It is some device that upon receipt of an input signal actuates something to produce a controlled output. This could be a pressure switch where a diaphragm pushes on a microswitch so that when the input air pressure reaches a certain pressure that sufficient movement of the actuator occurs to change the state of the microswitch. In general a relay is an amplifier, meaning a small input signal can control a large output. Isolation between input and output is generally a property of a relay.

Most relays you think of are electromechanical with an input coil to create a magnetic field when a current is applied. Thre magnetic field via an armature moves a contact to open or close a circuit.

Attached is a photo of the side of a P&B KUP 11D15 24 V DC. This relay can switch a 10 A load at 120 V (1200 W) with 24 V at 450 ohms (53 mA) 1.28 W. Thus the power amplification is 1000.




In the photo you can see one terminal of the relay coil and its connection to one tab on the relay base. The other end of the coil is on the other side of the relay.

At the top right you see the SPDT contact structure and the center contact is supported by a leaf spring that via a flexible wire connects to the tab next to the relay coil tab. The relay in its present position is de-energized and the normally closed path is to the upper tab. When the relay is energized the center contact moves to the lower contact and this is the called the normally open contact.

You can easily test a plug-in relay by pulling it from its socket and applying the correct voltage and frequency to the coil. You can also measure coil resistance. If you have doubts about a relay bench test it.

You should be able to look inside an "ice cube" relay and see in what state it is.

You can ignore your control switches and apply an appropriate voltage to the "ice cube" relay to see if it controls your contactor. If things work correctly here, then you need to work on the control wiring and switches to see where your problem is.

Your control switches are wired in what I call a "wired or" circuit. That is the normally open switch contacts are wired in parallel. Thus, any one or more switches when closed produce a logic one or true condition. One set of contacts on a switch are used to set the contactor on, and the other set of contacts to set the contactor off.

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[mgookin]

I drew up a simple schematic of what's happening at the relay assuming you can figure out from there that your momentary toggle is a DPDT switch which supplies both positive & negative DC voltage to the relay which switches the hot leg to the lighting contactor. See below (assuming I can post a picture on here):

 

[gar]

151028-1035 EDT

I doubt that the controlling switches are DPDT spring return to center. Rather these are likely SPDT spring return to center, such as the control switches in a GE RR relay system.

Call the switch terminals A, B, and C where C is the center switched contact. The likely wiring is all the switch C terminals are wired together and to one side of the power source for the "ice cube" relays. The other side of said power source goes to one coil terminal of each of the "ice cube" relays.

All switch terminals A are connected together and to the second side of A's relay coil. Closing any one or more switches to their A position energizes relay A.

All switch terminals B are connected together and to the second side of B's relay coil. Closing any one or more switches to their B position energizes relay B.

Ideally there should be exclusion logic to prevent both A and B ftom being energized at the same time.

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[Wire 2 Race]

Looks like the contactor coils are 120vac so those auxiliary relays are just there to allow LV (24vac) control. What I'm seeing is that there are five 18ga wires coming into that terminal block. Do three (R,B,W) go to the SPDT center off switch and are the other two 24v from a transformer?Those other two (white and black) are what I can't trace. It goes out of the box, around the room and disappears into a 2" C under ground. There is another "phone" room on site, but the conduits coming up in there do not have matching wires as what leaves the subject room. They have a phone/intercom system. Had a guy out from that group who says they have nothing to do with it. Looks like the white is the common and the red and blue go to the coils. Thing is the other side of the coils goes to an unused terminal then off someplace I can't see. YES, the white is the common, with red and blue doing the switching. When I disconnect the black, and or the white, the contactor won't switch at all when I jump the 120 V side, in fact it makes a strange "hammering" sound like the contactor is going on and off real fast, but the lights aren't effected. ??????

Should be a simple matter to draw a schematic, the relay information is right on the covers. Unfortunately we can't follow the wiring from picture to picture.

-Hal

Thanks Hal, I'm going to go back to the site and spend a little more time there.

 

[hbiss]

Those other two (white and black) are what I can't trace.

I think we pretty much figured that all those two relays do is allow LV control of the 120 volt contactor. Thing is it seems more complex than what is needed to accomplish that task. Maybe it allows other options such as non-momentary switch control such as a time clock?

Don't remember if you found the 24v transformer or not. As I said above I can't see where the common side of the two coils goes. Maybe to an auxiliary contact on the contactor? It also looks like the white and black on the left have something to do with the control of the left relay. Which relay does what by the way? Which is ON and which is OFF?

Can you get a better picture that shows the whole panel wiring in one or perhaps two pictures side by side so we can trace it out?

-Hal

 

[gar]

151029-0940 EDT

Wire 2 Race:

Since the two "ice cube" relays are independent entities it is possible that a normally closed contact on relay B is in series with the coil on relay A, and vice versa. This would prevent both A and B being energized at the same time. This is the type of interlock I suggested in an earlier post.

If you tried to do this directly on the contactor without the auxilliary relays, then there is a timing problem.

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[teufelhounden91]

Square D lighting contactor wiring diagram

Do you know the wiring well enough to draw a simple diagram. It will help you get your head wrapped around where to go to troubleshoot.

Do you have a picture further back so we can see the whole picture? As Hal said there's some things there we can't see.

Have you tried tracing out wires from the push button to the cubes to make sure they're sending current to the cube coils when pressed? Can you hear the ice cube coils switching states (not the contactor) when the push buttons are pressed.

One of the coils in one of the cubes could be fried so it's not responding to input to unlatch the contactor. But still allowing latching/unlatching by jumping the load side wires as you've done.

Do you understand the diagram on the front of the cube relays?



Sent from my iPhone using Tapatalk

 

[hbiss]

The relay coils on the socket are the topmost screws just below the relay. (Google DIN relay socket and find one that looks like that for the pinouts.) You can see how they are wired- one side of one coil goes to one side of the SPDT switch and the other relay coil goes to the other side of the switch. The other side of both coils are tied together but we can't see where that wire goes.

The contacts are a complete mystery since we can't see any of where they go.

-Hal

 

[gar]

151029-0854 EDT

Looking at post 1's photo I conclude the following:

1. Assign numbers to the terminal block from left to right as 1 thru 7.

2. The hot side of the 24 V secondary terminates on TB1 and TB7. The common side terminates on TB5. 24 V AC or thereabouts should read between TB1 and TB5.

3. The right hand coil terminals on the "ice cube" relays are connected together and to TB5.

4. Call the left relay A, and the right one B.

5. The coil A hot terminal goes to TB2, 3, 4 and to white and red wires, then to the control switches.

6. The coil B hot terminal goes to TB6, and a blue wire to the control switches.

7. TB1 and TB7 come from the secondary hot terminal, and to black and white wires to the control switches.

8. The "ice cube" output contacts are wired with A and not B in series with a Sq-D coil, and a not A and B connected in series with the other Sq-D coil. This provides the exclusion to prevent the simultaneous operation of both Sq-D coils. "A" means normally open, "not A" means normally closed. Same for B.

Draw the circuit and you will see how it works.

It may be possible to get the Sq-D "ice cube" relays with an LED indicator light. I have a DC unit with such an indicator.

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[gar]

151030-1151 EDT

There is a name for every one of the sixteen possible logical functions of two binary inputs. I don't remember the names of the ones that I do not use, and I could not find my reference for the names. The Internet was no help.

To write logical equations various typewritter symbols are used. Here I will use / before the variable to indicate NOT, ^ as the OR inclusive operator, and & as the AND operator.

So the following equations would describe each of the previous circuits.

O1 = first Sq-D coil = A & /B
O2 = second Sq-D coil = /A & B

An interesting point here is that if you parallel these two circuits (parallel is an inclusive OR function), then the result is an exclusive OR circuit.

Exclusive OR of A and B = ( A & /B ) ^ ( /A & B ). This means the output is TRUE (1) if either A or B is asserted, but not both. Further if neither is asserted or both are asserted, then the output is false ( 0 ).

 

[gar]

151030-1261 EDT

Symbolically the circuit can be described in ladder logic form as follows:

  Wall switches       Ice Cube coils
  SPDT spring
    return to 
    center

  The ON direction
    switch contacts
  |-----| |-----|
  |             |
  |-----| |-----|-------(A)------|
  |                              |
  |                              |
  |    Off                       |
  |-----| |-----|                |
  |             |                |
  |-----| |-----|-------(B)------|
  |                              |
  |                              |
  |---------- 24 V AC -----------|



  Ice Cube Contacts   Contactor coils
         A       B
  |-----| |-----|/|------(ON)----|
  |                              |
  |      A       B               |
  |-----|/|-----| |-----(OFF)----|
  |                              |
  |                              |
  |--------- 120 V AC -----------|

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[donburde]

I must be missing something, what are the point of the ice cube relays. If the contactor unit is mechanically held, you shouldn't need then. .. momentary contact on the "contactor close" terminal and the lights come on... momentary contact on the "contactor open" terminal and the lights go off... what are they using the icrs for?

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[mgookin]

I must be missing something, what are the point of the ice cube relays. If the contactor unit is mechanically held, you shouldn't need then. .. momentary contact on the "contactor close" terminal and the lights come on... momentary contact on the "contactor open" terminal and the lights go off... what are they using the icrs for?

Sent from my SM-G928V using Tapatalk

Control is 24VDC. Might come from a BMS (building management system) and the toggle is an override.

Contactor coil is 120VAC.

 

[gar]

151030-1420 EDT

donburde:

I believe the "ice cube" relays perform two functions.

1. Allow low voltage low current wiring to the controlling switches. Study a GE RR low voltage system.

2. Provide an interlock to prevent simultaneous application of power to the Sq-D contactor coils.

In post 32 I provided a ladder type diagram of what I believe is the circuit. Study the circuit and see why both contactor coils can not be simultaneously energized. If you do not understand the circuit ask questions.

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