UPS on light circuits

[shanky887614]

it would be better if you routed all the circuits through another board otherwise it wont comply.

it will be no differnet than linking a genny to the grids neutrel and earth

 

[davesparks]

it will be no differnet than linking a genny to the grids neutrel and earth

How so?

 

[shanky887614]

How so?

or are you thinking of putting a tpn changeover switch with the ups only on one phase?

 

[uksparks]

it would be better if you routed all the circuits through another board otherwise it wont comply.

it will be no differnet than linking a genny to the grids neutrel and earth

How would it not comply? Surely if it is labelled accordingly it would be ok?

I was just thinking, I wouldn't need to link the neutral to the supply neutral, I could just disconnect the neutrals from the main neutral bar and put them into to their own isolated neutral bar that only goes via the UPS.

The earth I would still connect to the main bar though.

 

[davesparks]

or are you thinking of putting a tpn changeover switch with the ups only on one phase?

I'm not thinking of doing anything with it.
I want to know how this would be the same as joining a generator N and E to the public supply.

 

[davesparks]

How would it not comply? Surely if it is labelled accordingly it would be ok?

I was just thinking, I wouldn't need to link the neutral to the supply neutral, I could just disconnect the neutrals from the main neutral bar and put them into to their own isolated neutral bar that only goes via the UPS.

The earth I would still connect to the main bar though.

The plan is getting better, but covering it in labels won't achieve anything.

 

[uksparks]

Maybe I should just put an expansion board on the bottom with the light circuits in with the supply to it from the UPS, that way it's all separate.

do you think that would be better?

i know you say it wouldn't comply the other way, can you point me in the direction of a reg to look at as I'm not sure I can find one as I feel it seems possibly wrong but don't think it is.

i can't see that having in the same board would be a problem but would probably be better in a separate enclosure I suppose.

 

[spark 68]

How would it not comply? Surely if it is labelled accordingly it would be ok?

I was just thinking, I wouldn't need to link the neutral to the supply neutral, I could just disconnect the neutrals from the main neutral bar and put them into to their own isolated neutral bar that only goes via the UPS.

The earth I would still connect to the main bar though.

This is a more sensible Idea, but ideally Shankys separate board idea is the way I would do it with the UPS primary supplied from a way in your existing board , with totally separate N and E bars for the UPS supplied circuits

Depending on the UPS they run in at least two different modes, some of the better ones have three modes.

Mode 1 is just in bypass while everything is healthy, Line + Neutral (*leaving the E for the moment)
Mode 2 in UPS mode, when the primary supply has failed, depending on how the UPS is configured, this output can be totally isolated from the incoming supply (both L + N), now to the E, * depending on the type of UPS if it is of the totally isolated type it can switch the out going CPC onto one side of the now fully floating side (ie. the designated out going N) making a pseudo TNC-S (CNE link) system on the output side only, this is to maintain the protective measure of ADS.
As you can see during power failure if you joined the incoming N (main side N) to the out going N (and like wise incoming and out going CPCs) you would be creating a N-E short on the outgoing side of your now dead main DB, and also still be partially connected to the grid which is against regulations when using a backup supply.

Mode 3, some computer type UPS have a so called "brown out" mode or "power clean up mode", this mode is less clear cut, and not all makers will divulge fully how they implement this mode being a "propriety" technology aka selling point, types with this facilities are less suitable for what you have in mind.

 

[Dcf]

I sorted out a bit of a shambles left by some mob with ups supplies for commercial led strips.
i think it was about 300va load each
schneider made the ups which were large and considerably heavy
there were 2 Spurs one for the supply and one for the output if I remember correctly.
the units themselves were about 600mmx300mm
they seem to work similar to an inverter drive with AC in rectified to a DC bus line and then turned into a nice smooth AC out the other end
the led strips were fed through a dmx board with relays and the like but I've no idea how it was programmed .
i think your idea should work but you will be surprised of the size and cost of a decent ups

 

[uksparks]

Spark 68, thank you for this, very informative.

May e putting an expansion board on with the RCBOs for the circuits fed from the ups with its own neutral and earth would be best. That way i know it's separate and will be ok.

The other way is easier but equally this way sounds better and more sensible.

Ill have a look into the UPS supplies and find a suitable one, I don't need a massively powerful one as it's only for lights which are all LED and like now for example only using 36w on one circuit and about 15w on another...

I wonder if I could put a manual change over switch in it too so that I can override the UPS should it go faulty.

 

[uksparks]

Just need one of these on the bottom (obviously AMD3 compliant when the door gets updated)

Hager JK116EG Din Extension Box 16 Module

 

[spark 68]

I did have at one time a white paper with the different categories of UPS, but that was over 10 years ago so god knows where it is now lol.

There were basically two main types if I recall with further sub divisions.

The most expensive were the type that converted (rectified) the incoming mains to DC and then used an inverter (and a backup battery) to give the AC output, I think this type was called the full or dual conversion type, the bypass mode was not used via AC in and out, if the mains failed the switching was done at DC level between the rectifier and the battery pack.

The cheaper types used a bypass mode between the AC in and out, this was the type I mentioned earlier.

Then you have expensive types with pure sine wave outputs and some (most) of the cheaper types kick out more of a stepped square wave called an approximate waveform , sometimes this can be important depending on the application.

When designing anything other than single computer/server backup plug and play types it is important to know exactly the topology of the UPS you are intending to use.

If I find (unlikely ) that white paper you are welcome to it, the actual regs may have changed slightly but the physics and actual electrical principles have stayed the same.

 

[shanky887614]

bassically the cheap ups are off and only turn on and take over when power goes off but this has draw backs for example the voltage drops then spikes during this period.

the other type powers everything off the batteries and just uses the mains to charge the batteries


i know there more complex than that but thats bassically it dave over on the eevblog explains them a lot better (eevblog on youtube)