Transformer question

Hi,

I know a LOT has been discussed regarding transformers, and I spent some time reading through them all.
I have one question, however: I decided to spec wire-wound transformers because of various reasons, but if I run 4 x 50W downlights per 1A channel, I am out of the dimmers parameters.

Instead of going 3 and push up costs, would there be any adverse effects at all if I just limit my dimmer channel to 90% (with the resultant increase in lamp life) and still connect my 4 lights per channel?
I suppose the problem will come in when you switch the circuit with the local override, but anything else?

Thanks
Brodsky

 

The Atco Wirewound tranny has a loss of around 15 to 18W when running with a 50W lamp. That means allowing 68W per lamp, so you should only run THREE on a 1A dimmer channel

The solution is to use 35W IRC lamps, which give the same output as a standard 50W dichrioc lamp. And the tranny losses should be lower too - lets say 35W + 15W = 50W total, so you can easily use 4 per 1A channel.

The IRC lamps cost a little bit more, but have excellent rated life and the very best beam control... and whatever extra they cost will be MORE than offset in energy savings...

If you are in Australia, then forget 1A dimmers and use 2A... much easier and costs no more to use 2 x 2A vs 1 x 1A...

Cheers, John

 

i have the 3x L5508D1AP and 1x L5508D1A dimmers
and about 100 downlights (50watt osram decostar titan holgen globes)
with ATCO TED-070A Speedy 50watt electronic transformers

i thought the output of the dimmers was 250watts per channel

however

i have the Electronic_Tranformer_List-23-04-02.pdf

which says i can only fit 3 transformers per dimmer output?

can someone confirm the number of transformers i can use per output

most of my zones are actualy only 2-3 transformers per zone
some have only 1...

however a couple are 6-7... which i was going to split over 2 outputs..

but whats the go

will i get problems with too few downlights...
and whats the maximum and what problems happen if i use 4 or 5.

i mean 5 x 50watts is only 250watts... still meets the output maximum of the dimmers.

im not sure why thats not allowed...

any advice appreciated

d
d

 

Hi T666

On a 1A dimmer channel you can have a maximum 300pF of capacitance *OR* a maximum 240VA of load.

Firstly, 1Amp at 240V is only 240W. Next, you are forgetting that the transformer has internal losses. For an Electronic trannie it works out at 4-5W (fairly irrespective of the loading) - so your 50W lamp draws about 55W on a Electronic trannie, or about 65-68W on a Wirewound trannie.

Atco TED70 is only 33pF each, so there isn't an issue of capacitance on the 1A and 2A dimmers. However, there IS a loading issue... since each 70VA trannie could theoretically be connected to 2x35W of lights, it can actually draw a maximum of 74W, and 3 x 74 = 222W. That is why the CIS chart says only 3 x 70VA transformers on a 1A, or 6 on a 2A channel.

From my own experience, there won't be any problem loading a 1A dimmer with 4 x 50W lamps using TED70's. If you have 5 or 6, then split them evenly over 2 channels (eg: for 5 downlights use 2 & 3 rather than 1 & 4 on the respective channels)

Regarding under-loading, you won't have any problem running 1 x trannie on a 1A output. In my previous job we had heaps of 1A and 2A dimmers that were only loaded with 1 downlight... no problems experienced whatsoever. There IS a minimum loading, but I think it was 20W or something like that - but I know that 50W and even 35W lamps work fine.

Your idea of splitting a group across 2 x 1A outputs is valid, but the 2 outputs will need to be kept separate (don't try to connect 2x1A channels together then run 1 cable out to the 6-7 lights !

When sharing a Group Address, the separate channels will very accurately "track" each other - so you won't notice any difference between the 2 groups once installed.

Hope that help, John

 

Beware the false economy

In reference to the use of 35W IRC globes I tend to design the circuit based on the size of lamp that could be connected to the fitting and not what I think should be connected for best efficiency etc. Once I leave the site I have no control over the customer who decides that he will save a few dollars by buying all his globes at the two dollar shop and loads up the circuits with 50W globes.

Regards,

Peter Brown.

 

we have more trouble with input capacitance control rather than loading, especially with Professional Dimmers. In many cases, we involved in the control parts only and those transformers aren't chosen by us. Anyway, it is difficult enough to tell client to spent more money on a higher power dimmer because of so much power loss by those transformers, but also tell them that they can't have 12 pieces of 50W light on a 5A dimmer channel because the Capacitance is too high!!

In our local market,the transformers in Clipsal's list are rare. Many transformers has no information on its input capacitance anyway. Perhaps we should ask our local CIS to give us an official transformer list for our client to choose from.

Anyway, (1) what happens if the capacitance is over? and (2) what is the 32IEND doing and will it help Professional Dimmers? (3) Is there any way we can reduce the coil sound/noise in the dimmers when used with electronic tranformers?

(By the way, the max. input capacitance should be 300 nF for 1A dimmer)

 

I agree with pbelectrical regarding loadings - in a CONTROLLED environment the 35W IRC lamps are very good, but only if the client is smart (well trained) enough to realise that they can't just chuck a 50W lamp in there. Anyway, running dimmers, relays, contactors, switches, MCBs and RCDs right up to their maximum rating is poor practice anyway - leaving headroom makes the installation more flexible and also should prolong the life of the rest of the circuitry.

From my experience, the dimmer channel overheats and blows.

Note that there are comments made that the input capacitance causes a greater "loading" on the dimmer - ie: a 70VA electronic transformer magically becomes a 100VA load. This is not technically correct, it is still (effectively) a 70VA load, but it is a partially CAPACITIVE 70VA load.... and that capacitance kind of causes a Leading Edge dimmer to be "fighting against" the load once the output waveform starts to chopped (dimmed).

The solution in all cases (although STILL not available for Wired Cbus) is to only use a Trailing Edge Dimmer on capacitive loads (which is what electronic devices tend to produce). Hopefully we will soon have Trailing Edge dimmers available !

OOPS, yes that's correct ! I have just edited my post accordingly.

JC

 

thanks heaps for the info ill def save this!

I checked all my globes and they are 50w osram decostar titan
But i only have 1 Atco TED70 transformer per downlight

If each Atco TED70 only ever conects to 1x50w (maximum draw of 55w)
Then 4 x 55w = 220w
So 4 transformers/downlights 220w max total per 1A dimmer output should be sweet???

I need to know 100% if i can get away with the 4 transformer/downlight zones
I dont want buzzing sounds or dimmer/globes blowing
Can u confirm this will b alright in my situation?

Otherwise im going to have to buy another dimmer
That wont fit in my enclosures, which are [2] x 40 Module Metal Enclosures model: 4C18MEB
I already have the pc interface, 4x8chanel dimmers and 2x4chanel relays

The one other issue is the wall uplights which are only 20w globes...
They are single 20w lights on their own dim zone...
You said this may casue a problem...
Can i place some additional load to them somehow?

i heard about the 32IEND, i dont know what it does or if it can help?


here is my zone plan if u have time to check it out that wood b cool!


DIMMER 1 L5508D1AP

Dim Zone 1: Bed A Desk [ 2 x 50w = 110w ]
Dim Zone 2: Bed A Bed [ 2 x 50w = 110w ]
Dim Zone 3: Bed A Ceiling [ 4 x 50w = 220w ]
Dim Zone 4: Bed A Wall [ 1 x 20w = 22w ]
Dim Zone 5: Bed B Desk [ 2 x 50w = 110w ]
Dim Zone 6: Bed B Bed [ 2 x 50w = 110w ]
Dim Zone 7: Bed B Ceiling [ 4 x 50w = 220w ]
Dim Zone 8: Bed B Wall [ 1 x 20w = 22w ]

DIMMER 2 L5508D1AP

Dim Zone 1: Bed C Desk [ 2 x 50w = 110w ]
Dim Zone 2: Bed C Bed [ 2 x 50w = 110w ]
Dim Zone 3: Bed C Ceiling [ 4 x 50w = 220w ]
Dim Zone 4: Bed C Wall [ 1 x 20w = 22w ]
Dim Zone 5: Bed D Bed [ 2 x 50w = 110w ]
Dim Zone 6: Bed D Ceiling [ 2 x 50w = 110w ]
Dim Zone 7: Bed D Wall [ 1 x 20w = 22w ]
Dim Zone 8: Bed D Veranda [ 3 x 50w = 165w ]

DIMMER 3 L5508D1AP

Dim Zone 1: Stair 2 [ 3 x 50w = 165w ]
Dim Zone 2: Stair 1 [ 4 x 50w = 220w ]
Dim Zone 3: Entrance [ 4 x 50w = 220w ]
Dim Zone 4: Laundry [ 2 x 50w = 110w ]
Dim Zone 5: Bath A [ 3 x 50w = 165w ]
Dim Zone 6: Bath A [ 3 x 50w = 165w ]
Dim Zone 7: Bath B [ 3 x 50w = 165w ]
Dim Zone 8: Bath C [ 3 x 50w = 165w ]

DIMMER 4 L5508D1A

Dim Zone 1: Lounge Zone 1 [ 4 x 50w = 220w ]
Dim Zone 2: Lounge Zone 2 [ 3 x 50w = 165w ]
Dim Zone 3: Lounge Wall [ 1 x 20w = 22w ]
Dim Zone 4: Dining Table [ 4 x 50w = 220w ]
Dim Zone 5: Dining Wall [ 1 x 20w = 22w ]
Dim Zone 6: Kitchen Bench 1 [ 4 x 50w = 220w ]
Dim Zone 7: Kitchen Bench 2 [ 2 x 50w = 110w ]
Dim Zone 8: Kitchen Ceiling [ 4 x 50w = 220w ]



peace

D
D

 

ps: subnoat:
i agree wit plan for the 50w(55w max) globe but if i returned all my globes (still in box) and used 35w instead
would that be beter? if 35w globes are less heat than the 50w globes i think i would prefer that as long as they arnt half the light strength... also....could i get away with 5 transformers per zone??? i know that may be bad practise cuz if i put 50w globes in by mistake something would blow... but

5 x 35 (say 40w max) = only 200w...

1 downlight will only ever be associated with 1 transformer... im not sure if im allowed to run a single 35w globe with the Atco Ted70 but if it was... could i get away with this setup

Ill be sweet with 4x50w(55w) zones as described anyways if thats cool, im just also interested in the 5x35w(40w) possibiblty

peace

D
D

 

From my own experience, there will be no problems with 4 x 55w = 220w loading on the 1A dimmer.
Buzzing of lamps is separate issue - it is unlikely, but occasionally some people will notice it... nothing that can be done, it will happen with any phase-chopping dimmer - but electronic transformer (theoretically) will be less prone to it. At least the transformers won't buzz, which can occasionally happen with wire-wound trannies if the laminations or windings resonate.

The TED-70 is rated for 20 to 70W loading, so there will be no problem loading it with 20W or 35W. The TED-105 is rated for 35 to 105W loading, so that wouldn't work well with 1 x 20W lamp.

There will be no problem with 5x35W, but you will need to remember that you don't have any "headroom". So, if you (at a later time) used 5x50W (total 275W) you would put the dimmer under a lot of stress and may blow it up (eventually, as they are NOT as fragile as some UK users seem to believe).

Not in this case, the 32IEND is used to counteract the problem of too much capacitance, with is not of major concern with Speedy or Possum transformers. You would need to have 300/33 = 9 x TED70's on 1 dimmer channel before you'd need to consider a 32EIND.

---------------------------

For info - the Osram IRC 35W gives the same amount as the 50W Titan - and heaps more light than a cheapy 50W lamp. The difference is mainly in initial cost (about double) and the advantages of lower electricity costs (15W @ 11c/kWh for 1500hrs/yr (domestic) = $2.50 saving per year (so it more than pays for itself).

---------------------------

Oh - and I just found a Speedy brochure - the TED70 has 4W losses, the TED105 has 6W loss. So, to calculate circuit loadings, just add the rated wattage of the lamps - for example:
35W lamp on a TED70 = 39W
50W lamp on a TED70 = 54W
2x35W on TED70 = 72 (it actually under-runs the lamps a bit)
2x50W on TED105 = 106W
3x35W on TED105 = 108W (also slightly under-runs at max loading)

---------------------------

Last - significantly prolong the life of your lamps by setting the MAX level in each Dimmer Channel to 90 or 95%. You will never notice the drop of light level (if you never actually see what 100% does). But at 95% your lamp life will be doubled, and at 90% your lamps will last 4 times as long ! This is a very very good thing to do !

In our Lighting Showroom we run the incandescent lamps chandeliers etc at 75% presets (ie: they always switch on at 75%, but can be dimmed up to 100% manually). One unit has 50 x 15W pilot lamps rated for only 500 hours life - it has run at 75% power for 10 hrs every day, 6 days a week - it has been going for 3 years (about 9000 hours) without any lamp failures !
- This is good because we need scaffolding to get up and change the lamps
---------------------------

Cheers, John

 

thanks dood your a legend

i may go with osram irc 35w lights if i can swap back the ones i already got
the downlights are all pretty much just for mood lighting anyways and i was going to cap it at 90%. its not a cafee or a library its a house

almost every zone only requires the 4 transformers/downlights

but i might need to go to 5x35 in just 2 areas downstairs... but ill try not too

i appreciate all the advice i think i got it down

peace

D
D