Blackout Contactor

[LX-Dave]

This is probably a bit of a stupid question, but here goes...

 

I've recently discovered a device near the dimmer rack in our school theatre, and I'm intrigued as to what it is for, It is a small black box with big green and red 'Start' and 'stop' buttons, it has a label on the side of the box which says "Blackout contractor control switch". I guess it is something to do with the house-lights (which are fluorescent tubes), as there is a box near to the breaker boxes labelled "Main Hall Contractor"

 

Any suggestions appreciated,

Dave

[Stee_cri1]

Hi mate

 

dont mean to sound arragent or anything but have you tried pressing it to see what it does?

 

Stee

[LX-Dave]

Hi mate

 

dont mean to sound arragent or anything but have you tried pressing it to see what it does?

 

Stee

 

I'm in fear of pressing it, just in case it does something 'undesirable', particularly when 'the boss' isn't too far away ;)

 

Dave

[IRW]

Hi there, this sounds very like our emergency lighting blackout button, which we can use if we desire a full auditorium blackout. There is a timer function built into it though, so it can only be used for about 5 minutes at any one time.

[paulears]

I suspect it says 'contactor' - a nice simple way of controlling larger amounts of power remotely. They can be wired so that circuits can be cut off when the power drops out or a remote circuit condition is applied, and have to be reset manually. This is often seen on feeds to power amps where if the fire alarm goes off, the amp rack cut out, allowing people to hear the alarm. To get it back on again a button press is required. They can also be used to allow dimmers to be turned on and off remotely, so maybe somewhere near the control, out front, there might be another button to turn the dimmer feed on and off? They are really just chunky relays. They can be wired so that a momentary button prod latches them on, and they stay powered until the supply is cut off, or they can have a remote on/off switch. In your case, there's no real way of predicting for certain what it does, but I'd stab a guess that if you hit the red ones, the power to the dimmers and possibly the 13A sockets in the main hall may be cut off. I'd follow the cable route. If it goes away from the dimmers, then there may be another button somewhere!

[LX-Dave]

Hi there, this sounds very like our emergency lighting blackout button, which we can use if we desire a full auditorium blackout. There is a timer function built into it though, so it can only be used for about 5 minutes at any one time.

 

It could be that, although I don't see why, since (IIRC) the emergency lights (apart from the little red LED's) only come to life after a loss of power to the regular lights ?

[IRW]

Hi there, this sounds very like our emergency lighting blackout button, which we can use if we desire a full auditorium blackout. There is a timer function built into it though, so it can only be used for about 5 minutes at any one time.

 

It could be that, although I don't see why, since (IIRC) the emergency lights (apart from the little red LED's) only come to life after a loss of power to the regular lights ?

 

Ah, fair enough- we have the other type that are always on!

[LX-Dave]

@ paulears

 

I believe there used to be a second switch (the first being by the dimmers) at the back of the hall next to the control kit, however, I think this may have been removed during a refurbishment. IIRC the cable runs away from the dimmers to the opposite side of the stage (where the main power stuff (RCD's etc.) for everything in the the hall that isn't stage lighting are located. so I doubt it's anything to do with the dimmers etc.

 

I did have a brief look at the setup earlier on, but I still wasn't sure so I thought I'd put it to the guys on here. as far as I could tell, the cable from the switch runs to a box under one of the breaker boxes, then into said breaker box; from memory, this box contains breakers for the fluorescent lighting, wall sockets, and amp racks, there is a separate power supply and breaker box next to this system although it is not labelled.

 

the contactor can't be anything to do with the amp racks as you suggested, since we only had a PA system installed many years after the contactor was fitted

 

dave

[Mexi]

The only time I've seen a school hall with contactor controlled lighting is when early automatic lighting controls were installed. It seems a strange way to control modern fluorescents but I would assume previous lighting could have been tungsten.

 

The emergency lighting may have been changed at some point, that could be why a black out switch was installed. If a central battery system was installed previously, this may have a drop out relay - I.e switch the low voltage supply on when the main lighting failed. But I think this unlikely

 

The only other thing I can think of is maybe old powered black out blinds?

[LX-Dave]

The only time I've seen a school hall with contactor controlled lighting is when early automatic lighting controls were installed. It seems a strange way to control modern fluorescents but I would assume previous lighting could have been tungsten.

 

It is quite likely that previous lighting was tungsten, I believe it has been changed many times since the hall was built in the 60's.

 

The only other thing I can think of is maybe old powered black out blinds?

 

this is very unlikely, I think the hall has always had manual curtains.

[pstewart]

Could it be an override switch for the hall's normal fluorescent lighting, to prevent helpful people turning them on during a performance?

[DrummerJonny]

just try pressing it. if bad things happen, pretend it was an accident?

 

/bad advice

[Kazeja]

Hi mate

 

dont mean to sound arragent or anything but have you tried pressing it to see what it does?

 

Stee

 

I'm in fear of pressing it, just in case it does something 'undesirable', particularly when 'the boss' isn't too far away ;)

 

Dave

 

 

Have you asked the boss what it does? If the boss does not know then I would have thought it would then be in their interest to find out. Now where did I put that wooden spoon?

[Davethsparky]

I've recently discovered a device near the dimmer rack in our school theatre, and I'm intrigued as to what it is for, It is a small black box with big green and red 'Start' and 'stop' buttons, it has a label on the side of the box which says "Blackout contractor control switch". I guess it is something to do with the house-lights (which are fluorescent tubes), as there is a box near to the breaker boxes labelled "Main Hall Contractor"

 

From the two labels I would guess the control point near the dimmers doesn't work the contactor near the DB. If it did the control point would more likely be labelled as the 'main hall contactor control switch' or the contactor be labelled as the 'blackout contactor'

 

'Main hall contactor' I would expect to be switching the lights in the main hall. It is not at all unusual to control flourescent lights from a contactor, one example is workshops where the lights are spread across the three phases and all switched from one switch.

 

The 'blackout contactor control switch' could have operated a contactor connected to an old dimmer system which had no dead blackout facility, and so the contactor would have been installed to provide this. I have heard of this type of control being fitted to some old manually operated resistor dimmers.

 

If no-one can tell you what it does I would say your best bet is to trace the wiring and see where it goes. Does it look old like it pre-dates the current setup or is it fairly new?

 

A contactor is purely an electromagnetically operated switch, simmilar to a basic relay but capable of switching high current.

[LX-Dave]

From the two labels I would guess the control point near the dimmers doesn't work the contactor near the DB. If it did the control point would more likely be labelled as the 'main hall contactor control switch' or the contactor be labelled as the 'blackout contactor'

 

not to discount your suggestion, but I think it is likely to control the main hall contactor, since this is of similar styling and (as I discovered to day) also identified as a blackout contactor (there is a label next to it, which says something along the lines of Main Hall = Power control = via blackout contactor

 

'Main hall contactor' I would expect to be switching the lights in the main hall. It is not at all unusual to control flourescent lights from a contactor, one example is workshops where the lights are spread across the three phases and all switched from one switch.

 

I am also of the opinion that this is what it does, due to its location, and where it seems to be wired up to [the cable going to/from the top of it runs towards one of those old metal master switch boxes (which controls the hall lighting) and the cable running to/from the bottom of the contactor goes towards a wall-box containing a fuse (unlabelled) (the fuse box is much newer looking than the contactor or master switch) ]

 

The 'blackout contactor control switch' could have operated a contactor connected to an old dimmer system which had no dead blackout facility, and so the contactor would have been installed to provide this. I have heard of this type of control being fitted to some old manually operated resistor dimmers.

 

this is unlikely, I think the earliest system in use here was 0/10v analogue dimming (although there is no-one left who would remember)

 

If no-one can tell you what it does I would say your best bet is to trace the wiring and see where it goes. Does it look old like it pre-dates the current setup or is it fairly new?

 

I spoke to 'the boss' today, and she has no idea what it does, although she guessed it would be something to-do with providing a full hall blackout :unsure:. The contactor is considerably older than the current setup (since that was only put in last July). I do not know (and am unable to find out) if it was put in with the previous system or even earlier, however, the styling of the contactor box is very similar to the schools master supply switches, which are the originals.

I am finding it difficult to trace the wiring as it runs under the stage (which is dark and has limited access).

 

Thank-you for your help, Dave