Contactor, Timer Circuit Design HELP!

[tennis ball]

I have a question.

Basically I have been asked to install electrical heaters in a large area and the customer wants them timed and on thermostatic controls. Which is fine you can just buy the plug in's right?

Bloody hell their expensive!

I haven't played with contactors and din rail timers before and I was considering putting the entire circuit on a timer as the heaters have built in thermostats. But I noticed the DIN Rail timers all have low current ratings up to 16A. Each heater is 2 KW and so can draw around 8amps and theres four of them!

So is it possible to wire a timer to output to a contacter and would the timer be able to turn the contactor on and off? Thats the simple question really as I don't have a clue about the design and workings of contactors and timers.

Any help much appreciated

Dan

 

[Des 56]

The timer output can be used to complete the control circuit of the contactor/s(which pulls in the contactor/s contacts)
This will be a small current and can be fed off a 6 amp mcb


With a ring you feed the contactors main incoming contacts all off the ring mcb, you then have the timer doing its bit with 2x 2 pole contactors with the coils wired in series,
The load side of these contactors can then be via their own mcb or fuse,which can give overcurrent protection to the individual heaters wired as radials,much like a Grid switch system in a domestic kitchen

 

[ackbarthestar]

TB....
Some things to consider
1/ Before you do anything draw a circuit diagram of what you would like to happen
2/ Draw a wiring diagram showing the position of the time switch/s contactor/s and how you are going to make the physical connections with mcbs covering the control circuit and final heater circuits
3/ I personally would use radials fused separately to each heater.
4/ There are various ways of wiring the control circuits, but in this case, I would keep it as simple as possible. One time switch with one contactor.
5/ If you use a 4-pole contactor then the phase and neutrals will be balanced, so you will need to link/loop the phase contactor and neutral contactor inputs together. You can then run 4 circuits via 4 separate MCBs in pairs across the contactor output.

Don't take any notice of the ones marked in Red (avatars) they are members of the local Old Peoples home where they sit around watching TV and discussing the benefits of Wonga dot com

 

[bugsy]

I've proberbly missed something but would not the timer control the contactor coil ( not input or output ) - thats what i thought the op said

Im waitin for the flack!

 

[Darkwood]

Your correct Bugsy the only flack you will get is you haven't read through this thread this mis-phrasing of what the O/P intended has been brought up already and OP was relating to timer energising coil on contactor.

 

[Knobhead]

Drawing based on a MK timer and Telemechanique contactor

View attachment 12271

 

[JUD]

Here's a diagram I knocked up for a thread a while back and shows how the timer and contactor can be wired up.

Just replace the light circuits with your heater circuits

 

[Mewff91]

Hi im an industrial electician and use contactirs and timers all tge time

Basically a contactor is a big switch
It has a suoply to the coil normally a1 and a2. Make sure you get a 240v coil.
The supply can be taken from the timer to the coil of the contactor on A1, A2 is the common (neutral)
The contactor will switch on by current passing through the coil.
The contacts off the contactor will then go to tge desired heaters.
They will then have supply to them when the contactor is energised.

As for the timmers and thermostats

I would personally have the contactor coils conected the the thernostat. This will then energise and cut the supply to the contactor depending on the temperature.

In regards to the timers are tgey goong to be used to cut the supply once tge heaters have been on too long or to come on at certain times?

 

[Knobhead]

Without knowing the full details of what’s needed in this case we can all guess.

It can be made as simple or as complicated as needed. One thing always to keep in mind is to keep things to the level the customer wants and the circumstances require.

 

[Darkwood]

Hi im an industrial electician and use contactirs and timers all tge time

Basically a contactor is a big switch
It has a suoply to the coil normally a1 and a2. Make sure you get a 240v coil.
The supply can be taken from the timer to the coil of the contactor on A1, A2 is the common (neutral)
The contactor will switch on by current passing through the coil.
The contacts off the contactor will then go to tge desired heaters.
They will then have supply to them when the contactor is energised.

As for the timmers and thermostats

I would personally have the contactor coils conected the the thernostat. This will then energise and cut the supply to the contactor depending on the temperature.

In regards to the timers are tgey goong to be used to cut the supply once tge heaters have been on too long or to come on at certain times?

No disrepect here but your either drunk or the worst lad in the english class...... never seen so many errors in a reply in the 3 yrs on here.

 

[Knobhead]

Could be worse

Hi im an industrial electician & uz contactirs & timers aL tge tym
Basically a contactor iz a big switch
It hz a suoply 2 d coil normally a1 & a2. mAk suR U git a 240v coil.
d supply cn b takN frm d timer 2 d coil of d contactor on A1, A2 iz d comN (neutral)
d contactor wiL switch on by curNt passing Thru d coil.
d contacts off d contactor wiL thN go 2 tge desired heaters.
dey wiL thN hav supply 2 dem wen d contactor iz energised.
az 4 d timmers & thermostats
I wud personally hav d contactor coils conected d d thernostat. DIS wiL thN energise & cut d supply 2 d contactor depeNdN on d temp.
n rgds 2 d timers R tgey goong 2 b Usd 2 cut d supply 1ce tge heaters hav Bin on t% lng o 2 --- on @ certan times?

 

[Darkwood]

Thing is i understood yours Tony ... must be drinking the same beer

 

[Mewff91]

God some of you guys are very sad. To actually sit there and rewrite my post, must be poor electricians and have no work. This website has been made for helping others, clearly you think your above everyone but its ok because you do sound really cool man much love!

 

[rameez]

yes, that's the only way to operate the heater . use correct contractor other wise it will burst very fast.

 

[adamh]

Soz tennis ball was writing when you replied to that.... never mind just a thought would have been better over 3ph but in this case just supply a timer and set it to energise and de-energise the coil on a contactor, if getting a 4pole contactor as suggested i would clarify the 4th pole is rated as this is usually there for the retaining contact and isn't always rated the same as L1,L2,L3...(phone call to tech' support may be needed) also you need to state the coil voltage when buying (230v in your case),.

why is the 4th pole for retaining the contact ? is this for some form of overide switch ? and if so this would assume you have a permanent neutral to A2 im guessing so no DP isolation or a seperate neutral ran to it? or am i totally wrong lol

 

[Darkwood]

In a 4pole contactor its basic design function is to let 3phase through, the 4 pole is used as a latch to keep the coil energised so in this set up a start and stop button can be used, and if power is lost on the control circuit the contactor will drop out automatically, a very good feature to have if controlling a motor and the power fails... last thing you want from a safety point of view is the motor starting unexpectedly as power is regained.
Having said this contactors can be used for a whole variety of tasks but to re-iterate some manufacturer cut costs by not making the 4th pole to the same loading standards as the L1-L2-L3 poles.
Yes the neutral is normally permanent and feed is switched with regards to 230v coil.