LED lamp damaging dimmer

Hi,

I have searched the forum but could not find anything dealing with this specific problem.
Any input will be appreciated.

We use L5508D1A to dim 5W dimmable OSRAM lamps of the 220V type, no transformer.
The lamps work well and dims smooth. Our minimum dimming level is set to 20%.

Problem: We are now on our third replacement dimmer in a 3 month period with random channels on the dimmer being blown or damaged. This means that the triac/circuitry inside the dimmer gets damaged by the LEDs. The channel either gets stuck and damaged in the "on" or "off" or "somewhere in-between" state but there is no definite pattern.

The affected circuits thus far have between 4 and 7 of these LEDs connected.

This is the first time in all the C-Bus years that we encounter this.
Could it be some harmonic or resonant frequency or something else created by the lamps that damages the dimmer.

Will it help to connect a wirewound transformer with 1:1 or any specific ratio in series?

Please advise.

Thanks.

 

To confirm the exact bulb specs are:-

LED SuperStar PAR16 50 35? Advanced
1000cd 7W 25000h
Dimmable (IEC 60064)
GU10

I measured the five bulbs to have an average in-rush current of 95mA and an average capacitance of 33.2nF.

 

Hi Brodsky

There is a dimming compatibility chart here.

http://www.osram.com.au/media/resource/HIRES/342571/63953/led-superstardimming-compatibility.pdf

One thing I noticed in that brochure is a general rule of thumb to not exceed the equivalent halogen wattage of LED's per channel.
From that, 7 per channel sounds like too many.
4 seems reasonable but your experience is suggesting otherwise.