genny system

original system (scrapped looking for new ideas)

** Ignore this bit the idea has been scrapped I'm looking for new ideas, toward the end of the thread (page2) **

note: not in operation genny has not been connect nor will be conneted untill everything is complete
the genny has a output of 6.5kva

here is the original version i first put together
1) its a two contactor system both n/o
2) each contactor has its own control relay (2a 250v contact double pole, 12v dc coil with internal diode)
3) the main change over relay is a double pole double throw (two way) and the n/c connection (when the relay is dead) goes to the mains contactor control relay and the coil (230v) is energised when the genney is powered up and switched on at the main unit (switch is 250v rated) thus turning off the relay controling the mains contactor and energising the genny contactor control relay then engageing the contactor
4) both contactors has its own lumination on the main unit to tell the user if its engaged
5) the main unit has a lumination to tell the internal dc transformer is working
6) volt and amp meter telles user how much current is being used and the voltage out put (so i can work out how much power is being used and how much surplus there is)
7) everything is fused to protect the circuit
8) start and stop button for remote start and stop (when the genny has a auto choke and starter motor installed)

images below:

Well there is no way you can provide a mechanical interlock on what you have there!!

If you're determined to include a Generator into your mains system, then be wise and purchase a made for purpose Transfer/changeover switch either manually operated or automatic...

What is the make/model of the generator you intend to use for this installation, and does it incorporate a decent AVR on the alternators output??

Hi engineer I am totally re designing the part of the system with the contactors I shall be changing them to the same make moving both into the same box and having a interlock between them I asked in the first post if everyone could hold off a reply till I got the second half on only wanted to show the changes from what I had to what I will have from what I've been told and advised on what I got now is being scrapped (least the contactors in two places) shall have the other section on tomorrow not got enough time now as I'm in work at 8:15
shall also get the exact model number off the genny after work it's buried in the shed at this moment in time

You may want to consider two timers in the control circuit of the contactors, this will stop the "chatter" problem alluded to by Lucien in the other thread.

The contactors will have to be physically side by side to fit the mechanical interlock between them

As much as I admire spirited thinking and creativity...... are we simply not just reinventing the wheel, here? An off the shelf changeover unit would be much quicker and cheaper?!

They will be side by side mate the armoured cable going to the shed is a 6mm 4core (not ideall would rarther have two cables but it's only temp till the shed is re built in the near future)
how ever I have found a good price changer over switch on eBay (£60 with a clad box) only concern I have with a switch is it's inaccessible where the house c/u is I'll have my mother call me every time the power goes out and why there's no power when the genny is running and not something I want if I'm ever fault finding a pain in the back side break in a ring main but if the new version I have in mind is still a big concern I'll just scrap the lot and go with a change over switch and ignore any calls from my mother when at work

Rockingit said:

As much as I admire spirited thinking and creativity...... are we simply not just reinventing the wheel, here? An off the shelf changeover unit would be much quicker and cheaper?!

Click to expand...

possibly if you know to a place that has them for less than £100 so far I spent less than that (£50 I can get back just wacking the contactors I got on eBay as for the relays I'm allways dabbling with electronic circuits so will find some other use for them)

IME buying off the shelf ATS works out cheaper for the smaller sizes, and will be compliant, making your own does work out cheaper for the larger sizes or custom built ones sometimes, but building your own needs properly testing and certifying, I have done both.

Just had a look on rs components and found out there's 4pole contactors with two n/o and two n/c poles

if I can get a 63a 4pole 2n/c and 2n/o (our main fuse is 60a) contactor would it be better and be safer and also have a delay on it to allow the genny time to fully spin up

so say have the genny on the n/o side and the mains on the n/c side start the genny when there's a power cut after 3 seconds or more the contactor will energise and isolate the mains and connect the genny to the house

whats you views on this guys?

Please do not try to do this on the cheap, no disrespect meant, but you are clearly out of your depth.
Either buy a proper bespoke system, or forget it.

There are implications that you have not thought of, and attempting to do what you are trying to achieve will likely end in tears.

The internet is no way to try to learn what you are trying to do.

This is the best advice I can give you.
Sorry I am out.

I'm not trying to do it on the cheap if I wanted to do it on the cheap I would have got a £60 basics changeover switch in a metal clad box but though my mum knows 0 about electrics so would be better if all she had to do is turn the generator on and not have to climb on chairs just to flick the switch to change it over she isn't getting any younger neither is my dad and I won't be living at home forever so I come on here to learn about generator installations and work out the best course without it costing a arm and a leg

at least I sought advice before going any further I knew a guy who had a length of flex with two plug tops one either end he pluged into his genny and the other into a socket then he would turn the main switch off on the c/u then start up the genny now surely you cannot get any more dangerous than that no Rcd protection and no fool proof isolation

Bernard1991 said:

I'm not trying to do it on the cheap if I wanted to do it on the cheap I would have got a £60 basics changeover switch in a metal clad box but though my mum knows 0 about electrics so would be better if all she had to do is turn the generator on and not have to climb on chairs just to flick the switch to change it over she isn't getting any younger neither is my dad and I won't be living at home forever so I come on here to learn about generator installations and work out the best course without it costing a arm and a leg

at least I sought advice before going any further I knew a guy who had a length of flex with two plug tops one either end he pluged into his genny and the other into a socket then he would turn the main switch off on the c/u then start up the genny now surely you cannot get any more dangerous than that no Rcd protection and no fool proof isolation

Click to expand...

Please don't tell me you are serious?

The courses have a cost for a reason, not to deter you from doing them but because of the effort and time people have put in learning about them so it can be done safely.

That statement makes a Electrical Trainee sound lime they know what they are doing.

To the OP
Cost cannot be the main and overriding concern where safety of the user and others is put at risk for the sake of a few pounds this coupled with the distinct lack of knowledge you possess regarding generator switching is a recipe for disaster

Your best option is forget it or spend some cash and get someone in who knows what they are doing