[Voodooman]

Hi,

Just hoping someone can shed some light (no pun intended) on a transformer and noise issue I have. Please bare in mind I am not an electrician.

I am using a Lutron Grafik eye 3000 to control various lights. Some of these lights are X-flex 24v Xenon bulbs on a twin core flex powered by trannies. All due care has been followed to ensure the appropriate trannies (capacity) per amount of bulbs is correct and the total load is within the capacity of the Lutron. All this has been installed by an electrician.

What is annoying is that *some* of the lighting runs buzz quite loudly. Not only that - they make the Lutron buzz as well. I have had several discussions with Lutron, Trannie manufacturer and X-flex supplier, all tending to pass source of issue onto one another.. .

I know you will always get some noise from transformers but.. .

Can anyone suggest a way of eliminating the buzz or at least reducing it without changing the controller and type of lights I am using?

Thanks
V.

[101music]

Have you seen the Lutron transformers? Might be worth a try

[Voodooman]

No, any chance of a link?, google brings up many types of result.. I assume you are refering to in cupboard/ceiling transformers rather than wall/switch mount devices?

V.

[dalethecaptain]

You may have the right 'trannies' for the power of the lamps, but are they the right transformers for the Lutron Grafik Eye?

Lutron transformers are shown here.

Lutron units don't like certain types of transformers, you need to be sure they are all compatible with the Grafik Eye. Roughly how far is the transformer from the furthest lamp? I ask this because as you start to get over 1.5-2m in cable tail length to the light fitting from the transformer output, this will generally start to cause 'hum' with the Grafik Eye.

And when you say they are on 'flex', what sort of cross sectional area (size of cable) is the cable in use?

Is the earth connected at the light fitting and at the Grafik Eye?

Also make sure your high and low voltage cables are well separated in any void spaces where they could cross each other.

I would certainly consider getting the electrician back in as it is not right if the unit is buzzing.

[Bruce_]

buzzing is normal, especially if it's a toroidal transformer (wirewound)

Lutron can supply a debuzzing coil, designed to solve this problem. You could try using one, or perhaps replace the transformer with an electronic one. both options aren't cheap, but the result will be worth it.

[Voodooman]

Originally Posted by dalethecaptain

You may have the right 'trannies' for the power of the lamps, but are they the right transformers for the Lutron Grafik Eye?

Firstly thanks for the feedback. I wasn't made aware that specific trannies were required for the Lutron so I have ones spec'd for the X-flex as sold by IdealsGB Ltd. These light runs come with PUMA model trannies (24v ELV) from mode-lighting UK. After some discussion (about the buzz and a possible remedy) they have since not got back to me or returned my calls.

Originally Posted by dalethecaptain

Lutron units don't like certain types of transformers, you need to be sure they are all compatible with the Grafik Eye. Roughly how far is the transformer from the furthest lamp? I ask this because as you start to get over 1.5-2m in cable tail length to the light fitting from the transformer output, this will generally start to cause 'hum' with the Grafik Eye.

Interesting. How are supposed to know what IS compaitable and what isn't with the Lutron (bear in mind I have been emailing a Lutron tech guy and he's not flagged that) (and why!) I digress.. Lutron 230/240v power runs to the trannies are up to 7m away. The runs from the trannie's (24v) to the first bulb is always <300mm. The longest bulb run (tail?) is 2.5m

Originally Posted by dalethecaptain

And when you say they are on 'flex', what sort of cross sectional area (size of cable) is the cable in use?

Its a twin core with approx 1.0mm copper strands (the xenon bulbs have a plastic click in 'seat' that pushes in to the flex - this allows the light run a fair amount of flexibility.

Originally Posted by dalethecaptain

Is the earth connected at the light fitting and at the Grafik Eye?

Most of the trannies dont have an earth, the larger ones (metal case's) do - but earth is not connected.

Originally Posted by dalethecaptain

Also make sure your high and low voltage cables are well separated in any void spaces where they could cross each other.

I have made sure that they run as best as possible

Originally Posted by dalethecaptain

I would certainly consider getting the electrician back in as it is not right if the unit is buzzing.

Long story. Original electrician could not complete as he emmigrated. This was because furniture maker had nervous breakdown and couldn't complete project and it took too long to find replacement cabinet maker willing to take on job. Original electrician recommended another before emigrating. He is Mr jobs-worth and blames anything on previous electrician and charges silly money. I fear the same scenario if I was to get a THIRD electrician.

V.

[Voodooman]

Originally Posted by Bruce_

buzzing is normal, especially if it's a toroidal transformer (wirewound)

Lutron can supply a debuzzing coil, designed to solve this problem. You could try using one, or perhaps replace the transformer with an electronic one. both options aren't cheap, but the result will be worth it.

The Electric option sounds interesting. Bearing in mind the Xenon's are 24v and vary in load/run can you get electric trannies for this and how big are they? Space and location is a bit tight in some places as the lights are in a furniture cabinet build.

V.

[dalethecaptain]

I am surprised you have a buzzing issue with these units, I myself have Mode transformers, I think they even used to make transformers for Lutron!

The length of your low voltage cable tails is nothing to worry about. I'm not sure about the 1.0mm wire though, I would have to consult the manual on that one. Not having the earths connected is fine, often this can be source of noise and is not normally required for low voltage light fittings anyway.

Assuming we both have the same transformers, you have the 24v version of this model. These are already electronic low voltage units. Going by the PDF document it would appear that at 1.0mm CSA your wiring is undersized.

Its possible that although the transformer is a 'leading edge' dimming type and compatible with your Grafik Eye, your light load does not have a linear consumption when dimmed, and hence needs an artificial load to compensate for this. I am assuming it buzzes when dimmed, is that correct?

Just to be sure, you have not mixed types of lighting (eg Zenon, halogen, incandescent) on each individual zone have you?

Lutron make load ballast units, they are about 200 quid all in I think. You would need to get them to advise you which unit to be sure.

[Voodooman]

Sorry for the delay. Work commitments . All of the transfromers buzz and humm a small amount, it just seems that the xflex and xenons are more prone to create more noise.

I just checked the flex and its about 1.5mm to 2mm across (core) Yes some of the trannies are the ones you describe, however the worse ones are ET-24v-210-P-230-RD and ET-24v-315-P-230-RD which are bigger and contain more electronics, these cope with 210w and 315w respectively.

Originally Posted by dalethecaptain

Its possible that although the transformer is a 'leading edge' dimming type and compatible with your Grafik Eye, your light load does not have a linear consumption when dimmed, and hence needs an artificial load to compensate for this. I am assuming it buzzes when dimmed, is that correct?.

Both the Lutron and the Trannies buzz as soon as power is put through that circuit/zone. The 'heavier' the zone the more it buzz's. As you power the zone to full it buzz's less. I will say again though that the trannies are operating within thier power requirements but have a full load, the combined load is also not exceeding the 800w limit per zone from the Lutron either. I am going to do a small load test on one later to see if that makes any difference (ie 5 bulbs instead of 20)

Originally Posted by dalethecaptain

Just to be sure, you have not mixed types of lighting (eg Zenon, halogen, incandescent) on each individual zone have you?

No all zones are of a single type and the only ones making noise are the xenons and xflex. Some are multiple 105w trannies which are quieter, the others are higher rated trannies with longer tails.

Originally Posted by dalethecaptain

Lutron make load ballast units, they are about 200 quid all in I think. You would need to get them to advise you which unit to be sure.

Ok.. I have no idea what these are but will run this by the Lutron tech and see what he says. Thanks for your continued help, appreciate it.

V.

[intelelec]

Hello hoping you got your problem sorted. If not then change the transformers to the lutron models and this will sort out the problem. The guy who mentioned whether your transformers are leading or trailing edge was spot on. Whether your tranny is electronic will also affect it. Lutron use quite a complex method to dim lights and not everyones gear is compatible, simple as that really. This is why i would always recommend the Grafik eye intergrale to customers as this is very adaptable and will work with most load types.

[Isco 3]

I removed my Lutron transformers and replaced them with Mode Lighting ones. Lutron was a bad choice for transformers. I wasted a lot of money for 20 of them. The Mode Lighting ones are much better.