Contactor Conundrum.

[La Poste]

Greetings.

I have bought myself a Contactor to wire into the garage lights so they switch on when the electric garage door is raised.



Unfortunately it did not come with any literature and seeing as how this is the first time I have ever wired one I thought I would ask here for a bit of advice.

I am guessing that terminals 1 and 2 are for the feed signal from the door and terminals 3 and 4 are for the load which is the supply to the lights.

Is this correct?

The garage door has a small light that illuminates when the door is opened and I was thinking of wiring the feed to the Contactor in parallel with the light.

The supply to the garage lights (load) would go from a 6 Amp MCB, through the Contactor then to the lights and then back to the neutral of the board so the Contactor will be wired in parallel with the garage door light as a feed and in series with the garage lights which are the load.

Can anyone help me with this one?

Thanks very much.

 

[Darkwood]

A1 and A2 is the coil when you apply 230v to the coil it will close the contactor, check your garage door light is the same voltage as the coil on the contactor, then bring your mcb feed into terminal 1 and switch out of terminal 2, is the light you want to bring on existing and controlled by a switch or is it an independant light running of the contactor only.

 

[mechelec]

Look at the front of the contactor and all should be clear. Clue is A1 and A2 are coil terminals

 

[jumpin jax]

perhaps La poste is not seeing the wood for the trees, the A1 and A2 screws are the ones dead in the middle in front of the double pole inputs and outputs

 

[Guest123]

The issue I forsee is that the lamp in the door motor unit may be a different voltage to the coil contacts in the contactor.

Also, terminating additional cableing to the lamp terminals may be a right PITA.

 

[Knobhead]

A simple limit switch on the door would solve the problem. Take the contactor back and get a limit switch.

 

[La Poste]

That's great thanks.

I didn't realise A1 and A2 had terminals behind the screws, I was being a bit thick, I couldn't see the terminals at first glance.

The supply/feed to the garage lights will feed two switches.

Each switch will feed one bank of lights, each bank of lights consists of 2 six foot fluoro's so in total there will be four six foot fluoro's supplied by two switches.
Each pair can be switched independently.

So this Contactor is double pole with line load going through 1 and 2 and load neutral going through 3 and 4.
Is this correct?

The lamp in the garage door is definitely 230 Volts I checked.

Also the garage door light/ control signal has a timer built in and so this timer will be handy for turning the garage lights off automatically after about two minutes.

I am not sure what a limit switch is, I shall have to do some reading.

 

[Knobhead]

Does the indication lamp remain on when the door is open or just when the winding motor operates? If it’s on all the time the door is open your OK, otherwise you’ve got problems.

 

[La Poste]

It's a small lamp, low wattage 230V light bulb at the top of the control unit.

When the garage door is switched to open the lamp illuminates and stays illuminated for about two minutes after the garage door has finished opening then switches off.

The same is also true when the garage door shuts. The lamp illuminates when the motor kicks in and the lamp stays illuminated for two minutes after the door has shut.

If I can get the control feed wired OK I will take the supply from a 6 amp MCB, through the Contactor, through the switch and thence to the lights and keep my fingers crossed.

 

[Darkwood]

You could wire coil as suggested and have a feed from light switch feeding 1 and looping to 3, then 2 is switch to one bank of lights and 4 is switch to other bank of lights, you dont need to run neutral through contactor, this way all lighting will work via contactor.

 

[Marvo]

Some garage door unit lamps are supplied via a solid state device ie diac or triac. I would check the circuit first and if the lamp isn't supplied via a relay then use a separate limit switch to operate the contactor as previously suggested.

Also sometimes the garage door unit flashes the lamp several times before the door opens or closes by means of a warning. This would play havoc if you're using the contactor to supply fluorescents.

 

[telectrix]

why not just fit a PIR to switch the lights on, leaving the manual switch in parallel. that way the lights will come on if you enter by the back door as well.

 

[Marvo]

Yep, I agree. Even if for some reason a PIR won't work I can't help thinking there will be an easier way to achieve the goal.

 

[Knobhead]

If you want the lights to operate with the door I’d go for a limit switch. As Marvo pointed out the lamp could have a solid-state driver, which could be damaged by the inductive load of the coil. If you want to use the contactor try this

View attachment 11419

 

[Des 56]

why not just fit a PIR to switch the lights on, leaving the manual switch in parallel. that way the lights will come on if you enter by the back door as well.

I have done that on many occasions,the folks are generally thrilled by the magic of it all

Simple and easy to please folks with a simple system

 

[La Poste]

Thanks guys.

I am going to re-think this.

The unit does have a Triac.

The manual states in the specs "Triac 1A@230V"
So this is probably what controls the courtesy light as the lamp is rated at 40 Watts maximum although the manual does not say exactly what the Triac controls.

It's now a ---- up between the PIR and the limit switch, I shall have a think about this more but the main thing is not to damage the doors control unit so the Contactor wired to the courtesy light idea will have to go, it was a nice idea but too risky.

Thanks again people.

 

[Marvo]

Well good luck whichever system you decide on.

All these systems with triac operated lamps are going to be problematic when they phase out incandescent lamps. CFL's and Led lamps don't mix well with solid state switches.

 

[La Poste]

Just one more question, why do CFL's and LED's not like sold state switches?

Is this something to do with not enough current being drawn by them and thus not allowing the switch to operate properly?

 

[La Poste]

Also am I right in saying the collapsing magnetic field of the Contactor coil when switched off may induce a back EMF that could damage the Triac that is used for switching the courtesy light on/off?

A lot of questions I know but the subject's got me thinking.

 

[Marvo]

Apart from the poor quality waveform the leakage through the triac can cause the filter capacitor on the input rectifier of a CFL to charge and discharge which cause flicker even when the lamp is supposed to be off.
The capacitive load of a CFL ballast can cause the triac to stop conducting prematurely and make it multiple switch during a single cycle.
The LC filter in the CFL also causes chaos when it encounters the rapid voltage swings of the triac output waveform. Similar problems occur with the EMI filters and drivers in an LED lamp as well although LED drivers are far more complex and the latest LED lamps have been redesigned to have some of these issues addressed.

There are certain ways around these problems but you have to take the lamps on a case by case basis. As a general rule for an easy life rather just avoid using anything but filament lamp in a circuit that's switched by a triac.

 

[Engineer54]

Don't forget, you also need to be able to operate these lights from the existing switch too!!! ...lol!!!

 

[La Poste]

All the lights are already wired into a set of grid switches and work fine, it's just this little extra bit that needs sorting out.

 

[vaughant]

If you want a limit switch send me your address and I'll get you an old (but perfectly ok) one from work.
If the doors metal I'd use a proximity switch,that way you can set it a few mm off the top of the door so it never comes into contact with it like a limit does and won't wear out then but I doubt we've got any 240v switched ones,loads of 110v but your messing with transformers etc then,limit will do just fine.

 

[Knobhead]

Forget the 240V PX, I priced one for a job at work a few years back. It was enough to make your eyes water.
A limit is a cheap option, especially if you take vaughant up on his offer.

 

[La Poste]

I'll do a bit of reading this week, it's such a shame not to use the courtesy light, it really does everything I want, it has its own timer built in, it is right next to the board and it operates at 230 Volts, connecting the wires to a relay would be so easy.

It illuminates when the garage door starts to open and stays on for two minutes then switches off, perfect for what I want.

For a limit switch to do what I want it would have to be at the bottom of the door where it could be kicked or damaged, an optical device might be a safer bet you know the ones with a mirror, as soon as the door opens the beam is broken and hence the lights switch on, I could couple this with a timer and Bob's your uncle.

One other option would be to use the power to the motor as a feed to trigger a relay, as soon as the motor kicks in the lights come on, but when the motor stops the lights would switch off, maybe there is a device that can use the motor current as a trigger and then stay on for two minutes whether the motor has stopped or not.

This is entering into the realms of electronics, something I haven't studied in ages.

I just want the lights to operate when the door starts to open not when it is fully open and I want the lights to stay on for two minutes then switch off.

I shall let you know how I get on, maybe I will just give up and fit a PIR