Lightprocessor Dimension 610 Dimmer

[nickb12345]

Hi All

 

We have 4x Dimension 610 dimmers from Lightprocessor on a couple of our sites which seem to eat triacs for breakfast.

 

The load on these dimmers is either 2x 500w P64s or 2x1000w P64s - either way under the 10A load of the channel.

 

They were shipped with BTA12 triacs which, as 12 amps should be protected by the 10A ceramic fuse... but just about every time a lamp blows the triac (and fuse) blow too. The lamps are from GE I think, supplied by SLX, so not cheap ones or anything, and its been ongoing since the installation so rules out an iffy batch or anything.

 

We have tried upping the rating of the triacs each time and are now on something like BTA48s (massive great things) which (so far) havent blown, but everything below has. Lightprocessor tech support didnt seem that interested, just said keep putting bigger triacs in... but surely this shouldnt happen? Is it a design fault, or something else going wrong?

 

The two installations in question were done by the same company but about 2 years apart.

 

And anybody who is on the ball will notice I have just posted a thread in the Electrical & Power forum about a potential wiring issue on a site with Dimension 610 dimmers. Yes is the answer, that installation is one of these. Therefore I had assumed the triac issue was related to that, but its happening on a seperate site which isnt showing any other problems as per the other thread.

 

Any ideas?

 

Ta

 

Nick

[Brian]

I've seen fault current figures for a PAR64 of around 140 Amps; limited only by the impedance of the mains supply.

[nickb12345]

Indeed I understand that occasionally the fault current can be high and damage triacs etc - hence the need to replace them every now and again...

 

But this is happening every time a lamp blows, across several batches of lamps and several batches of triacs. Surely if the BTA12 triacs are not big enough to handle a normal fault current then the packs shouldnt be supplied with them?

 

Does anybody else have these dimmers? Anybody had a similar problem with them?

 

Ta

 

Nick

[musht]

Triacs are prone to it, its why Dimension dimmers have the triacs on clamp connectors, large as will pysically fit triac, 800V devices if you can fit them in in.

 

Could try FF rated fuses but they cost almost as much as the triac.

 

SCRs are historically less prone, something to do with DV/DT , but tend to need much bigger heatsinks and cost a lot more.

Edited August 31, 2010 by musht

[DrV]

I've seen fault current figures for a PAR64 of around 140 Amps; limited only by the impedance of the mains supply.

The current itself is not all that meaningful in relation to popping a fuse rather than a triac - it's the I²t value that is important. At the risk of asking the bl33ding obvious are you using quick blow fuses? Sorry - had to ask - years of tech support phone calls which end with "you have plugged it in haven't you?" :blink:

 

Dave

[nickb12345]

We have tried all sorts of fuses, quick blow, normal, glass, ceramic. All blow, but the triacs still blow at the same time!

 

Has anybody else used these dimmers before? I cant help but think we have checked everything and tried all possibilities and they just dont seem to be up to the job. As per my original post these are located in two different venues in two different parts of the country so it cant be supply related. Problems have been ongoing for a long period of time so can rule out suspect batches of lamps/triacs/fuses. So far the BTA48s seem to be a lot more reliable and we havent lost as many (one or two in a couple of months) but surely if these triacs are needed then the dimmers should be shipped with them as standard?

 

Ta

 

Nick

[Brian]

Odd, I don't think I have ever lost a triac in a dimmer rack.

[nickb12345]

Odd, I don't think I have ever lost a triac in a dimmer rack.

Have you used the 610's?

 

This is why im confused, I have lost one or two but most of our venues use Betapacks or older Pulsar units - never a real problem with these and they get just as much use as the dimensions - and most of the pulsar racks use BTA12 triacs iirc. Thinking about it I believe most of the triac failures I have seen have been caused by something other than lamps, like faulty wiring etc - cant think of any caused by lamps blowing, apart from these two venues.

 

I just dont understand why im having to put such massive triacs in these packs - and if they are required then why are the packs not supplied with them by standard. Its not like we are doing anything unusual with them.

 

Oh well, replacement with Betapacks is on the capital expenditure list for both venues.

 

Ta

 

Nick

[KevinE]

You might just have a very low impedance supply, ie very close to a large substation. Triacs and thyristors regularly blow thanks to popped lamps, it's not the dimmer's fault.

 

You could try fitting semiconductor fuses, on no account use T fuses. Also best to use ceramic HRC type (sandfilled) because glass ones can remain slightly conductive after blowing due to sputtering of conductive material and can have a prolonged arc.

 

Semiconductor fuses are marked FF and are a few pounds a pack more expensive, ie £1 a fuse rather than 10p a fuse. Whether you think that's worth the expenditure is up to you.

 

FF10A fuses

[Brian]

Have you used the 610's?

 

...most of our venues use Betapacks ... I just dont understand why im having to put such massive triacs in these packs ...

 

I've not come across the 610s. I've used plenty of others including loads of betapacks without problems. It does seem very odd.

[Dmills]

Silly thought, but what are the 610s using as snubbers?

 

Replacing a triac designed for snubberless operation with one designed for use with a snubber will often cause all sorts of amusing problems.

Another thought, were the original parts by any chance sensitive gate types? Replacing these with conventional units will often cause poor behaviour (either failing to trigger reliably or triggering but generating excess heat).

 

What is the PSC measured at the dimmer supply terminals, the presence of large induction motors or close proximity to a sub station can often cause a supply to apparently be very stiff.

 

Regards, Dan.

[nickb12345]

You might just have a very low impedance supply

I appreciate its possible but does it not seem a bit odd that these two venues, out of 24 up and down the UK, are the only two with triac issues, and the only two with these dimmers. One site is in South Wales and the other in Portsmouth.

 

 

Silly thought, but what are the 610s using as snubbers?

This was something I discovered through the powers of google a while ago and all triacs purchased since then (about 6 months) have defiantly been the snubber version (off the top of my head cant remember the code - is it a W or something?!) and I believe any used before that time were, but cant be sure. The snubber versions are required by these dimmers, I have confirmed that with Lightprocessor directly. Could using non-snubber triacs in the past have damaged another part of the dimmer maybe?

 

 

Another thought, were the original parts by any chance sensitive gate types? Replacing these with conventional units will often cause poor behaviour (either failing to trigger reliably or triggering but generating excess heat).

Not sure - how do I tell the difference?

 

 

What is the PSC measured at the dimmer supply terminals, the presence of large induction motors or close proximity to a sub station can often cause a supply to apparently be very stiff.

What is the PSC?

 

Generally speaking our sites use a fair amount of power and tend to (I have only been involved with any mains work on a couple) have their own stepdown transformers on site - by substation would you be referring to these, or something bigger?

 

Thanks for your help so far, I really do appreciate the suggestions and help.

 

Ta

 

Nick

[Brian]

Could using non-snubber triacs in the past have damaged another part of the dimmer maybe?

Very unlikely. And if it did not in a way that would cause the problems you are seeing.

 

What is the PSC?

Prospective Shortcircuit Current

 

It's a figure, usually in the 1000A plus range, which indicates how much current your mains supply can deliver when it's short circuited.

 

If you're at the end of a long piece of cable the resistance of that cable will reduce the PSC. If you're right next door to a substation then it'll be higher.

 

If you have site electricians, or can arrange it next time an electrician is on site, it's a fairly easy measurement to take. Measured at the connection point for the dimmers it might give you an idea of what is going on.

 

Do you have these dimmers installed on any sites where they don't exhibit the problem?

[nickb12345]

If you have site electricians, or can arrange it next time an electrician is on site, it's a fairly easy measurement to take. Measured at the connection point for the dimmers it might give you an idea of what is going on.

There are electricians on some sites, I will enquire and try and get a reading taken. Any idea what would be considered to be high or low?

 

Do you have these dimmers installed on any sites where they don't exhibit the problem?

Nope, only got these on the two sites. Everywhere else is either Betapacks, Rack 6's or older Pulsar units.

 

Ta

 

Nick

[StevieR]

The Dimension 610 is really an entry-level dimmer unit (retail is about £300) and the circuit design will not be as good as say the Paradime 6x10a unit. Our rep from Lightfactor has stated before that the 610's are fine for lower load applications but can be more prone to problems under high-current loads. This seems to be what you are experiencing. Perhaps ask your supplier if you could trade-up to the Paradime 6x10. Yes, its double the price, but a much better engineered unit.

 

Steve