Un-usual 3 phase problem

[Nolnoc]

Was the coin meter ever actually ever monitoring all three phases.From what I can make of it it wasn't.Maybe I've lost the plot.Please keep us informed,interested in this one.

 

[needasparks]

Was the coin meter ever actually ever monitoring all three phases.From what I can make of it it wasn't.Maybe I've lost the plot.Please keep us informed,interested in this one.

No was only ever on one phase, been in service for about 30 years. was always assumed all heaters would be used so tarrif on coin meter was turned up taking into account other phases so money put in covered the cost used, all was happy all this time then people using the heaters started turning off some of the heaters and come across the fact their money did not run out when certain ones were turned off. What i should have explained and i missed in my first post was that this is a hall used by the public for hire, hence it being a coin meter as no other form of payment would be any good. Different people use the hall for different things so now not all heaters in all locations are used. its only recently the penny dropped so to speak on the problem that the electricity used over the last 12 months was totally different from the takings of the meter. It was so obvious but no-one picked up on it well apart from some regular userswho i guess have been keeping quiet on finding it out.

 

[Darkwood]

There is a way but its not cheap and you will have to build it all from scratch and programme it, you need a multi-function energy meter, plc, coin slot with reconition system. Your energy over three phase is monitored and run through a plc which you write the software to convert the coins input into killowatts allowed which then will countdown but first because this is just a idea i would talk to technical of the link supplied and see if the meter can give said info to plc http://docs-europe.electrocomponents.com/webdocs/0e36/0900766b80e364a3.pdf

I use plc's in machine control so cant see why this cant be done it all depends on the meter giving a readable output for energy used to plc.
The link shows a monitoring system that can control outputs such as contactor looks like you get software with it but as i said a chat with technical will be needed first explain what you need etc and let them do the thinking.

 

[Silly Sausage]

EEEK!... you would create a star point on the neutral bar and send 415v through all the system.

Haha...hence my comment of more thought required!

 

[ipf]

Was the coin meter ever actually ever monitoring all three phases.From what I can make of it it wasn't.Maybe I've lost the plot.Please keep us informed,interested in this one.

Started reading not long ago and I was thinking along the same lines. Head scratching. Fair assumption that all the heaters would be used all the time. Depending on for how long, how much more has been paid than should have been, prior to someone having an economical brainwave?

 

[Knobhead]

This is something you should read http://www.ofgem.gov.uk/Consumers/Pages/Resaleofgasandelectricity.aspx

 

[darcy]

Pondering this one...

 

[Darkwood]

Well its time to pop to the beerhole and im going in the mind that ive given a solution albiet expensive, i can now have a drink and peace of mind that i havent been beaten by what seemed a simple question to start with
arty:

 

[needasparks]

That was the only option Darkwood i thought would be open to me, other than using 3 separate meters. There is always the option of multiple coin timers on contactors but then you run the risk of overpaying. However the heaters can be split into 4 areas so limits turning off locally. Time could then be calculated by the KW per coin.

IPF, it has only ever been measuring 6kw (2 x heaters) so cant over charge. only ever under charged when any are turned off.

Biggest job i have is trying to explain the options available to the client, if we are struggling to get our heads round it this then they need to sit down for a while.

 

[ipf]

Fair enough. But something is wrong. Maybe it was the easiest way out without causing problems? For a while at least!

 

[ipf]

That was the only option Darkwood i thought would be open to me, other than using 3 separate meters. There is always the option of multiple coin timers on contactors but then you run the risk of overpaying. However the heaters can be split into 4 areas so limits turning off locally. Time could then be calculated by the KW per coin.

IPF, it has only ever been measuring 6kw (2 x heaters) so cant over charge. only ever under charged when any are turned off.

Biggest job i have is trying to explain the options available to the client, if we are struggling to get our heads round it this then they need to sit down for a while.

Sorry if I misunderstood NEEDA, I thought you meant the tarrif had been adjusted. Not my area really. Too much thought maybe.

 

[needasparks]

I guess your correct, 30 years ago no one dreamed any of the heaters would be turned off and assumed full load but people now want it in all the colours and all the sizes with a cherry on top.

Its rum o'clock so as said gonna sleep on it.

 

[needasparks]

I like your thinking! Something like this maybe?
View attachment 8185

I wish it was that easy, Thats the part that wont work as neutral is at unity on three phase resistive load.
Think about it, if each phase runs 100amps would you have 300 amps on the neutral. 120 deg blah, blah blah.

 

[Kamikaze]

Interesting problem!

After banging my head against the wall for a while, how about this, put the meter on the neutral associated with these 3 phases only??? Probably needs more thought.

edit

probably a very dangerous way of doing it!
The heaters would still be live when the meter disconnects the neutral.

I like your thinking! Something like this maybe?

 

[ufkir]

why not work out what you get for a £1 lets say its an hour then wire from the load side of the meter to a timer thats set to give you an hour when energised and make the timer control your contactor so that it dosnt matter which heaters they turn off they only get one hour. one prob is that if they put in £3 at once they wont get 3hours unless you can adjust the meter.

 

[Knobhead]

I like your thinking! Something like this maybe?

View attachment 8189

Sorry kid that was the idea I dumped. Look in to how vector currents in the neutral work.

In = √((L1²+ L2²+ L3²)-((L1*L2)+(L1*L3)+(L2*L3)))

 

[Kamikaze]

It’s that Kirchhoff putting a spanner in the works again….lol. More thought required on this one, but I’m determined a creative solution is better than an expensive one. Back to the drawing board!

 

[malcolmsanford]

The obvious way for me is not to try and change a system that's worked for 30 yrs but to try and stop the people switching the heaters off, how are they doing this?

If there is a simple switch FCU they are activating remove the FCU and replace with a double pole keyswitch and if needed series a fuse holder into it on a grid arrangement. Or just enclose the FCU in a lockable enclosure.

If they are switching off from the equipment then bypass the switch on the equipment and utilize as above. If certain units are not needed then again on request the owner/caretaker can isolate them.

Would this work

 

[Kamikaze]

Just a timer coin meter which switches the coil on a 3 phase contactor would be the most sensible idea.

 

[Knobhead]

Just a timer coin meter which switches the coil on a 3 phase contactor would be the most sensible idea.

But not legal see #26