Univeral 2.5AMP Dimmer

Hi,

Does anyone have practical experience with low voltage halogens on the relatively new L5504D2U Universal 2.5Amp per channel dimmers?

My electrician has done 2 CBus installs and is convinced that he can only run 4 transformers from one channel.

I would have thought that 240V x 2.5A = 600W, therefore you could run 6 x 50W halogens quite comfortably.

If I can run 6 lights, then I save on extra equipment, so I need to understand if he is right or wrong?

He also seems to think that those dimmers require something more than just a 10A supply to run the channels. Is he right? My reading is that the system requires 1 x 10A circuit to power 4 x 2.5A channels.

Thanks.
Richard

 

I have used these dimmers before to fix some issues with large load and excessive transformers. From memory the largest circuit connected was..

8x60VA Atco Possum transformers. Each transformer was connected to 2x20W Halogen lamps. Should be a theoretical 2.3A.

I think we also installed an inductor filter module.

These dimmers work different to the older ones. Each circuit has its own feed so you can supply individual 10A circuits to each load if you really wish.
Also the outputs work in 2 pairs at 5 amps each. For example...

These configs are valid
Ch 1 = 3A, Ch 2 = max 2A, Ch 3 = 2.5A, Ch 4 = max 2.5A
Ch 1 = 1A, Ch 2 = max 3A, Ch 3 = 2A, Ch 4 = max 3A

This config isnt
Ch 1 = 3A, Ch 2 = 3A, Ch 3 = 2A, Ch 4 = 2A

Or so I have been lead to belive.

Regards
Phil

 

Thanks Nick and Phil.

Maybe he is basing it on the 1A Dimmer channels? That would only allow 4 transformers with 50W halogens.

 

I have recently done some proper power measurements on transformers

It's probably the VA (which includes Power Factor) that matters... so :

Osram "Mouse" HTM70
1 x 50W lamp : 53W 0.995PF 56.15VA
1 x 35W lamp : 39W 0.993PF 39.28VA
2 x 35W lamp : 75W 0.996PF 75.65VA

Atco TM50A-2 (black wirewound)
1 x 50W lamp : 60W 0.940PF 63.38VA
1 x 35W lamp : 48W 0.902PF 53.26VA

Let's allow 60VA for a 1 x 50W lamp (to be safe)... Thus at 240V :

2.5A = 600VA - And that means that you can connect 10 per channel

3.0A = 720VA - which means you could connect 12 to TWO of the "opposing" channels (as per filpee's post)

The electrician is becoming confused because of the CAPACITANCE limits on the older Leading Edge Dimmers.

 

That is very clear and certainly explains why I have been concerned.

Thanks for everyone's help.

Richard

 

Interesting as I cant find anything like that int he instructions.

So what you are saying that as long as you don't exceed 5A on the two adjacent channels you will be fine. - does that include
Ch 1 = 1A, Ch 2 = max 4A, Ch 3 = 2A, Ch 4 = max 3A

You can see that Ch 2 has exceeded the 2.5A by quite a way, but the total of Ch1 and Ch 2 is still only 5A.

Just to re-iterate, capacitance of the electronic transformers is now not an issue with this dimmer?

Mick

 

Yeah.. what NickD says. I forgot to mention in my post that 3 Amps was the max. Sorry about that.

 

I found the document that talks about 3A... it was an "internal" information sheet thingy ( note the spelling ) - dated 10/8/06 with the title :

n e w p r o d u c t f e a t u r e s a n d b e n i f i t s

Four independent dimmer channels, with each channel
capable of controlling up to 2.5A of load (i.e., 10A
maximum load per dimmer unit).
(Note: Up to 3A may be connected to a channel, as long
as any adjacent channels are not loaded to more than
2A).

I can't see any subsequent info that makes mention of this 3A, so I am thinking that perhaps CIS decided not to make a point of it (due to confusion by installers), or have re-evaluated the maximum ratings and have left it at 4x2.5A for reliability's sake.