Leading Edge dimmers ! Apparently I complain too much

I asked my vendor to supply leading edge drivers with my LED Light purchase. He insisted that he sold a large quantity of the drivers he had in stock to a large number of CBUS people and he even (sshhhhh) supplied some to other brands.

Anyhow I took them home and of course when I tested them they hummed louder than cheap tyres on a grooved road.

I took them back and after a dozen phone calls I finally got my money back. The driver was a generic branded ACTEC driver clearly labelled FOR TRAILING EDGE ONLY. 5 minutes on Google showed that ACTEC also make a LEADING EDGE driver in the same plastic housing.

I asked when they would be selling the other model driver and they replied NEVER because I was the only one who complained since Moses left Egypt.

So my question is ....

a) Is it safe to mix and match drivers and dimming circuits

b) Is the rest of the industry having industrial deafness that they cant hear the swarm of bees trying to get out the mismatched LED driver.

c) Do people care about being technically correct or am I supposed to be leaving that for someone else to fix.

 

Hi Tobex
It think it just reinforces the value of buying LED's which work such as Starburst or equivalent as the easier way to go.

 

Indeed. Though I was rather disturbed by the very "convincing" assurance that you could mix things up without consequences.

Is there a long-term problem ?

 

The fundamental issue here is that when the leading edge dimmer turns on there is a substantial inrush of current (could be several amps for a tiny 10W lamp) into the front-end EMI capacitor within the driver. To keep a long story short, this results in a significant voltage spike (up to 1000V or so) across the primary switching FET inside the converter that can toast it in short order. This voltage spike can also damage the dimmer. So, as a general rule, Leading Edge dimming with generic LED power supplies is a no-no.

Having said that, this is a situation that can be handled. By particular design within the LED driver the voltage spike can be suppressed, the excess energy dissipated and dimming compatibility with Leading Edge dimmers can be achieved (although there are still other problems to solve in addition to this one). It does make the driver more expensive, but it can be quite effective.

All of this is independent of the very significant EMI generated from operating capacitive loads with Leading Edge dimmers.

So, the question really comes down to how do you know that the particular LED drivers you're buying have been designed to handle Leading Edge dimmers sufficiently well that the driver life and dimmer life will not be reduced?

Many of businesses selling LED products are selling OEM products that they have not designed themselves. I suspect that most of them really don't understand what the actual issues are, but are just flogging whatever they can get cheap. Everyone is trying to make a buck out of LED lights at the moment. Designing and selling a quality product seems to be well down the list of priorities. For these kinds of guys, it's to their advantage that the market remain uneducated.

So, someone walks into the wholesaler wanting LEDs. All the wholesaler knows that he needs to do is be sincere and appear knowledgeable and he's got the deal. This is because he has some knowledge whereas the customer often has none.

At this point I'd also like to clarify that the above are generalizations. There are some real quality LED products out there and there are wholesalers who really know their stuff. It's just a shame that it can't be said of the majority when it comes to LED.

Good on you for sticking to your guns. The only way that wholesalers will be forced to educate themselves and stock the shelves with quality product will be through market demand. They're out to make a buck so they'll follow the market. The main language that seems to speak to electrical wholesalers is product returns.