LED compatible with forward phase triac dimmers

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junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
Does anyone have a list of or reference to a list of LED PAR30 lamps that are compatible with the old style forward phase switched dimmers.

All I ever see online is 'dimmable' without reference to dimmer type.

Church I do work for has some strobing problems with LED in a 20 YO Lutron central dimmer control setup so not easy or low cost to change out dimmers. 20 YO dimmer panel.

Note: The Lutron compatibility list says their old PN dimmers are not compatible with LEDs, but think there are some newere LEDs with circuitry to work with forward phase triac dimmers.
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
190130-2426 EST

junkhound:

Forget the compatibility tables.

First you need a dimmer that has stable trigger timing independent of load. Virtually all old two wire dimmers failed in this respect. A two wire dimmer derives its power to operate from the series connection of a load. Also thru this load it needs accurate zero crossing information for timing.

You need a three wire dimmer that works well with most loads, or it appears that the Lutron CL class of two wire dimmers work with many loads. A three wire dimmer will work with no load.

So find a dimmer that has stable trigger characteristics. Then, bench test with different LED bulbs to see what works.

I have found some CREE 9.x W bulbs that dim very well with a Variac or a Lutron CL.

You really need to do bench testing.

Where real severe problems occur is with phase shift dimmers driving a transformer or other saturable core device because of a DC component in the chopped AC waveform causing core saturation.

.s
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
190131-2130 EST

ELA:

If you maintain gate drive, then the SCR or Triac conducts.

In particular a three wire dimmer I have does work with no load. However, it does not have the dimming range of the Lutron CL. The three wire dimming range problem results from the design of the time delay circuit to turn on.

.
 

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
The OP is NOT trying to find a dimmer. They already have a dimming system that they have no intention to change. They want to find LED lamps that will work with their existing dimming system.

Unfortunately I think the only option will be trying different lamps and choose the one that performs the best.
 
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