Added a dimmer and now the mcb is buzzing

[gcx51]

i have a lighting circuit with now running 2 650w aurora dimmers running 19 low voltage downlighters.

up until yesterday the lights were operated by 2 seperate plate swithes.

The mcb is now buzzing, and this is only with 1 dimmer on and it's even louder with the second one on.

The lighting circuit is wired in 1.5 t&e and is protected by a crabtree 6A type b mcb. All low volt transformers are dimmerable.

I have tryed putting it on 10A type b, which reduced the noise but it still buzzed so I was considering trying a 6A type C.

There is no other lights on the circuit.

Any ideas?

Cheers...

 

[breezer]

i will bet its one of 3 things

1) dimmers are under rated (assume 50w lamps, 9 / switch =450w too much for dimmer)

2) Transformers are non dimable

3) 1 & 2

useless but true:

1) did you know, in order for a halogen lamp to work efficently the lamp must be hot in order for it to redeposit the metal back on the filament, which it can not do if dimmed

2) when using a dimmer for a halogen most dimmers should be twice the total load of the lights or bigger, so for 500w the dimmer should be 1kw rated

 

[gcx51]

so what your saying is the reason why the mcb is buzzing is because the dimmer is not rated enough?

 

[breezer]

yep.

it wasn't buzzing before was it? and the only thing chaged is the switch

 

[gcx51]

i will fit 1000w dimmers tommorw.

Cheers for your help

 

[gcx51]

installing 1000w dimmers did not make the slightest bit of diffrence.

The mcb is still buzzing when i lower the light level.

Crabtree B6 mcb

Aurora 650w dimmers

Electronic dimerable transformers.

9 lights = 450w
The wholesalers have said, that with the aurora dimers you do not have to double the power of the dimmer like you once used to!

I have tryed using 1000W dimmers, which made no diffrence.

Any other ideas?

Cheers

 

[breezer]

change the mcb? (or at least swop the cct with another of the same rating)

 

[Big_Spark]

gcx..are all the transformers identical? and have you confirmed they are dimmable..does it say this on them?

I have encountered issues with eLV Tx's when they are not identical..In past experience Aurora dimmers seem to work best with Aurora transformers..if they are connected to other makes, especially if they are from different manufacturers or of different ratings, they seem to cause issues with MCB's

 

[gcx51]

All the dimmers are made by tec-lite, the transformers are 100% dimmable, it says on the units and the packaging and all are brand new.

I did try using tec 1000w dimmers which are the same make of the transformers. but the mcb still buzzed.

Am i correct in thinking that moden dimmers reduce a part of the signwave/frequency, which the transformers pick up and causing the lights to dimm?


Could this be causing the mcb to buzz?

Cheers

Rob

 

[breezer]

dimmers can not alter the frequency of mains, they do how ever chop the sine wave up.

the transformer in your case is "irelvant" since your dimmer would still dim an ordainairy lamp.

your transformer does however get a reduced supply via the dimmer.

cheapo dimmers will make a lamp buzz because they do not have sufficent filtering.

put it this way.

i put you in a shopping trolley and pull you along a smooth road, but this road actualy has a depression in it, but you wont notice it becuse the road is long and you go in and out of the depression slowly.

now imagine its another smooth road, but this has lots of depresions i put you in the same trolley and pull you at the same speed you will now notice the depressions because you are going in and out of them faster (although you are still traveling at the same speed)

now those depressions are the electricty and you in the trolley is the mcb. (thats why it buzzes, becuse it can "feel" more depressions)

i trust this makes sence?

 

[Jim2287]

if u put higher frequency transformers in, you wont hear it ?

changed ballast in a fitting and that stopped mains hum - wonder if its possible to do same here

 

[gcx51]

It does make sence yes!

I asume that dispite it buzzing it will still operate correctly.

I may have to run them on 10A mcb's as this reduces the noise.

I have never had a problem with aurora dimmers and tec transformers, but there again I have never had more that 6 on a circuit...


Cheers