Build A Contactor/relay

[Laphroaig]

Thankyou Sir!

Yes I'm going for On Delay, it's the one that I can just about grasp how it works, delving into the others gave me a headache. I am a little troubled though because you say the on delay will kick in at lights on each day. I thought that the delay was initiated by the circuit being broken by the thermostat connected to A1 on the on delay relay when the room gets above the set point. Once the room temperature has dropped below the set point, the thermostat closes the connection, completing the circuit and the delay begins. The clock shouldn't affect the operation of the delay now as the current is simply switched through terminals 18 and 15 of the on delay relay. At initial lights on each day the grow room temperature should have been below the set point for the past 12 hours and therefore the thermostat will be holding terminals 18 and 15 of the relay closed when the 24 hour timer powers up the circuit and switches the lighting contactors on. The first on delay event should occur some time after that when all the lights have been on for some time, well we'll see.

Anyway the bits and bobs are coming in slowly, can't wait to get started! The 60A terminal block was a huge mistake, literally , it's huge, think I'm going to have to look again at DIN rail terminal blocks. Bought the wrong stuffing glands and without locknuts, doh! Fortunately the replacements came next day, whereas Maplin seems to need about a week to post a single relay.

Your help has been incredible thank you, and that's everyone at UK420 too. There's no way I would have attempted something like this without all the information you've put into the many posts I've read here.

[scraglor]

there is no we'll see, that's what will happen.

if you were to power the lights through the nc of the on delay, the lights would come on instantly, then when the room got too hot, the stat applies power to the timer and there would be a delay before the timer switched the lights off the timer starts when power is APPLIED to the timer, when power is removed from the timer, the timer simply switches off

the timing of the on delay is started when the thermostat applies power to the relay, not when it removes power, that would be an off delay...

you want an on pulse timer as i suggested... there is no need to be confused, as i've given you the circuit schematic, and all you need do is wire it up, then you can see the action of the timer. it's much easier to understand when you see it in action.

with the on delay, the 24hr timer applies power to the on delay coil through the normally closed contacts of the thermostat, the timing begins then after the time runs out the contacts close and turn on the lights.... when the thermostat trips, it removes power from the timer and the lights go out, when the temp cools, power is reapplied to the timer and after the set time the lights come back on

on delay = power applied to timer coil > timing begins > contacts operate and hold until power is removed

i.e. a delay after power is operated before contacts operate - on delay

on pulse = power applied > contacts operate > timer begins > contacts release after timeout

i.e. the contacts are pulse on then off after is applied

i think actually an off delay timer is better for your needs, as an on pulse timer starts timing as soon as the thermostat trips... which would actually be no good if the room didn't cool within that timescale.

an off delay is simply the oppostie of an on delay.

the lights are powered through the nc of the timer, when the thermostat goes high, the offdelay timer operates and breaks power to the lights... when the thermostat cools, the off delay doesn't turn off an reapply power to the ligths until the set time has elapsed (hence the name off delay)

there are two types of off delay, "off delay" and "true off delay", a normal off delay has a separate power source, and so can have long time settings, a "true off delay" means that all power is removed and capacitors that store charge keep the relay in until the timer runs out, and so only have short time setting in the order of seconds up to a few minutes.... true of delay timers are cheaper, but you would need a standard off delay

off delay = power applied > contacts operate > power removed > timer begins > contacts release

there is a delay after power is turned off before contacts release, a delay before contacts turn off

Edited December 5, 2011 by scraglor

[Laphroaig]

there is no we'll see, that's what will happen.

if you were to power the lights through the nc of the on delay, the lights would come on instantly, then when the room got too hot, the stat applies power to the timer and there would be a delay before the timer switched the lights off the timer starts when power is APPLIED to the timer, when power is removed from the timer, the timer simply switches off

the timing of the on delay is started when the thermostat applies power to the relay, not when it removes power, that would be an off delay...

Gotcha, took a bit to get my head round it but finally figured out why it won't work. Going to use the on delay in the fan controller I'm making and get a on pulse timer from RS right now.

Coincidently I've ditched the huge supply block idea and have decided that I would like to try DIN Rail terminal blocks instead. However I'm utterly bewildered by all the different types and wondered if you could recommend something suitable that can accept the 10mm supply and 4mm earth cables. Although I guess I only need worry about a 40A MCB that can accept the 10mm supply cable as that will feed the terminal blocks, although I'd like to continue to use the 10mm cable to connect the MCB to the DIN rail terminal blocks. I need a total of 7 live, 9 neutral and 5 earth terminals. I do not know what wire size or configuration of terminals I should be going for and how to select a jumper bars that match the terminals I choose. Should I be looking for pass through terminals? Utterly bewildered. Was going to buy a selection of the most promising looking and see what I could make out of what I ended up with but perhaps you can save me from wasting a few quid and several days deciding what I actually need. Also when wiring up the contactors will the solid core cable from the domestic T&E I have lying around be sufficient for wiring the lighting and control circuits or should I be using higher rated cable for the switched contactor terminals. I'm guessing that it should be okay as I believe it's rated at 20+ amps but it always pays to check.

Cheers

[scraglor]

tell me your exact loading requirements, where your supply is coming from, and a sketch of the circuit and i'll sort it out properly for you....

as for the on delay timer you already have, you're switching quite a large bank of ligths at the same time, this will cause a voltage drop in your circuit, and... well i can't be bothered to go into it, but it's not a good thing, so get an OFF DELAY timer as per my above post, for your temperature control circuit, but keep the on delay timer to create a delay between switching banks of lights to prevent such a large start up surge... an on pulse timer should work, but there is the potential for the room not to have cooled sufficiently within the timer setting and so the lights would come back on regardless of the thermostat, the off delay timer will only start timing AFTER the temperature has cooled sufficiently, so eliminates all risk

again, write out the details and i'll get back to you, and make sure you get an off delay timer (and not a true off delay timer) i'll message you with a link to the correct timer)

Edited December 10, 2011 by scraglor

[scraglor]

here's a sheet with different timer functions on it if you fancy pickling your head

http://www.farnell.com/datasheets/6436.pdf

[Laphroaig]

My head is suitably pickled... I want a RE7-PD13BU Pulse on energisation relay from the PDF but trying to find one on the RS Components website is what's giving me a headache. One possible candidate is.

Schneider Electric RE11 RB MU On Impulse Timer

Ahh yes that makes sense! Off Delay guarantees that the room temp has fallen below the threshold before reactivating. Nice touch. In that case.

Schneider Electric RE11 RC MU Off Delay Timing Relay

Is that suitable?

I have taken on-board what you say about the on delay relay and I will use it to stagger the activation of the second contactor that operates solely from the timer clock by a few seconds.

Edited December 12, 2011 by Laphroaig

[scraglor]

yep, that off delay will do nicely

[Laphroaig]

Well most of my bits and pieces have arrived, just a couple lost in the Christmas post. I'm happy with the design but I want to put a MCB, RCBO or RCCB in the box too.

What would be the best choice?

My lighting supply comes from a 40 amp MCB connected to the lighting controller with 10mm T&E. No RCCB or RCBO in the fuse box.

I've seen a nice cheap 40 Amp RCCB on fleabay that I think is suitable but I'm not sure if 30mA is too low for switching HID lighting.

I'm also not entirely sure how they fit into the circuit but from what I've learned about them the MCB provides something called over current and short circuit protection, whilst the RCCB provides residual current protection. The RCBO (the one that has dangly wires that scare me, 'cus my tiny brain can't understand what it does never mind how it works) is a combined MCB & RCCB.

As I have a MCB already I thought I'd use a tame looking RCCB, no scary dangly wires, quite comprehensible to my tiny brain.

Opinions please.

Peace

Edited December 15, 2011 by Laphroaig

[scraglor]

just get an rccb, 40A 30mA trip

an rcbo trips when there is a different current going out through the live terminals compared with the current coming back in through the neutral terminal.... AND if TOO MUCH current goes through it (like an MCB) if it's a single pole rcbo to go onto one of your fuse board outs, it needs a connection for neutral to return to the supply, this is the scary dangly wire (also they have an earth wire you connect which detects voltage on the earth... the rcbo you were looking at was simply a single pole fuse board mount version, you can also get standard 2 pole rcbo's which just looks like any other circuit breaker but twice as fat with two lots of terminals of course!

an RCCB is a residual current circuit breaker(an rcd means residual current device and covers both rccb's and rcbo's)an RCCB doe NOT break if too much current goes through it! only if the currents do not match between live and neutral (which means some must be leaking to earth, possibly through you!) the A rating on the device is how much current the contacts can handle!! not the point at which it will trip, it will trip when more than 30mA (in this case) leaks to earth. DO NOT supply a 40A rccb from a 63A MCB for instance, for if you were to pull 50A from your supply, the mcb wont trip, and neither will the rccb, but the rccb may be damaged by over current

as you already have an MCB in your fuse board, there's no need for an rcbo in your box, just use the rccb, don't worry about the 30mA trip, providing your equipment is in good working condition, this should be fine, ALTHOUGH! if you are switching a large amount of electronic ballasts, you may have problems! e-ballasts have filters on there input terminals, to ensure they get nice smooth electricity, they filter any distortion in the power supply to earth! if you live in an area where the power quality is poor, these filters may be working quite hard and sending a lot of electricity to earth and it could well become greater than 30mA and produce random nuisance tripping of your rccb... this is failry uncommon though, and MOST people never have any problems... but i've read of some people taking back 'faulty ballasts, slagging of grow shops etc, when actually it was there' power supply at fault

[Laphroaig]

Well I'm still waiting for a few bits but I suppose I can make a start. Finally ended up gettin' a box from Screwfix, made of steel, oops, couldn't tell from the catalogue anyway it doesn't really matter I suppose.

Drilled a few holes in it before I realised that the punch templates on the box are just for fun! It's like someone's just hit them at random with a hammer, so I marked out my own holes.

And got drilling, note to self: try not to set the carpet on fire apparently women can smell singed carpet for days afterwards. Even after it's been hoovered!

I stuck in the DIN rails and cable glands. Then I put the gubbins and whatnot inside so I could figure out clearances for the timer clock and thermostat mounted on the front panel. The box is slimline, only 75mm deep so it's a bit of a squeeze fitting the clock. However after much angst and burning of carpet the hole I made seems to be okay, bit wonky but I can live with it.

[Laphroaig]

Ooops ran out of photo storage space. Here's the last shot.

So now I'm waiting for my RCCB to arrive, meanwhile I have to attach the thermostat to the lid, drill a 20mm hole for the wires and find a rubber grommet the same size. Thinking of getting an 8 or 9 way power connector so I can disconnect the lid when I open the box. Then I can begin wiring it all up.

[Laphroaig]

Started the wiring up, broke one of the two tiny crappy plastic panel mounts for the clock, going to have to figure a way to fixing it, can't have a wobbly clock.

Back later..

Peace

[scraglor]

very nice, didn't realise you were mounting an MCB in the panel as well? there's no 'need' as your feed will be fed via a circuit breaker at the origin... it is handy to have a local mcb as well though, although if your supply is from a 40Amcb as well, it's hit or miss which one will trip? you'd be better off using 2 x 20A circuit breakers, one feeding each bank of lights ;)this way, if one side is overloaded or there's a fault, you still have a remaining bank of lights... also your local mcb will trip and not your main feed mcb

[Laphroaig]

Back to drawing board. 75mm box depth is adequate for everything but the RCCB, case closes but there isn't enough clearance to trip the switch, have cut a hole in the cover to give clearance but it isn't very good. Time to look for a better enclosure.

[scraglor]

why not keep it that way? surely that's ideal so you can reset it? just make the cut neat