Well most 12 or hight voltage buldb transformers I've had have just gone into overheat mode probably shorted turns and then the current has blown the fuses.
Brian
Well most 12 or hight voltage buldb transformers I've had have just gone into overheat mode probably shorted turns and then the current has blown the fuses.
Brian
Thats what I was after. Just taken on 15 flats in Rochester, all of which have ELV lights everywhere. Looks like I need to use a DMM instead of a volt stick.
You need to measure the volts under load. Which in practice means with a bulb in place. If you have 240v present at the input, the bulb tests the rest. Using a volt stick or DVM with no load tells you very little - especially with a SMPS which may not even switch on with no load.
They're not really transformers, more isolated (& lightly regulated) high frequency inverters. The most likely failure is to let the magic smoke out of the semiconductors with zero output though there could be failure modes leading to reduced output.
It is unlikely that there would be failure modes resulting in significantly higher voltage output and *very* unlikely that mains would appear directly on the output.
Chris K
ELV electronic transformers only work when they have the right load. Every one of them has both a lower limit, and an upper limit. You have to use a load which is within that range. Usually, it's a factor of 3 between the limits - some common ratings are:
20-60W 35-105W 50-150WOutside their working range, they will shut down.
What you could do is carry around a known working test 50W MR16 lamp with matching lampholder with leads. Then test the transformer by connecting this test lamp to it. 50W is a good choice because it's within the working range of many of the common transformers. You can try your test lamp by substitution first, and if that doesn't work, substitute the lampholder too (which also fail from time to time).
These transformers are dirt cheap anyway if you buy from the right place, so carrying some spares to substitute is also worthwhile.
In the case of 20W MR16's, I would consider replacing with 240V GU10 fittings (discarding the transformer) with an LED. (GU10 LEDs aren't yet bright enough to replace the higher wattage 12V MR16's.)
It happens that The Medway Handyman formulated :
Doing you really mean a transformer or a SMPSU?
In either case, you can get either symptom.
very hard for a pure transformer to give lower output without going up in flames pretty quickly
Only dimmable electronics can do that. I takes a very specific fault to get any others to actually reduce voltage and stay intact.
These Varilight units which I use (from TLC appear) state that they operate from 0W upwards to maximum rating
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