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[CliffyJ]

Not sure if this is the proper forum, and this is my first post, so I'm not sure about other technicalities here. But, here goes.

I am new to X10, and really want to stick with it. My problem is controlling a basic outdoor lighting transformer. It is an inductive magnetic wire-wound transformer, rated for dimming, 200W, 12VDC output, 120VAC (dimmable) input.

After speaking to X10 tech's, and reading the spec sheets, the XPDI3 seemed perfect. And after hooking everything up today, all worked perfectly, woo hoo!

BUT. At that last dimming increase step of the XPDI3, the transformer's input circuit breaker blows.    

At the second to the last X10 step-up of the dimmer, the voltage between the XPDI3 and the transformer is 121.9 VAC; and the transformer output is 12.4 VDC. With the final step of the XPDI3, however, the transformer hums, AC voltage goes to 107, DC voltage goes to 7.3, and the transformer's input circuit breaker trips.

Again, every dimming step below this works perfectly, going up and down. It's only that last step that messes up. These results are the the same, with and without a 12v load on the transformer.

I'm no electrician, but here's some guesses at causes and solutions:
 1. Is my house current slightly too high (122VAC)? And will a conditioner or limiter of some kind fix all this?
 2. Or, is the transformer's input circuit breaker too sensitive? And perhaps in need of replacement? (BTW, spec sheet says it's good for 4A at 32VDC / 250VAC; looking up the part number, I found the spec: http://www.digikey.com/product-detail/en/W28-XQ1A-4/PB185-ND/45062)
 3. Or, is there something about the XPDI3's functioning, in that last control step does something special, but intolerable to a downstream circuit breaker?

I really want to stick with X10 and solve this, and it seems I'm so close! So thanks for any ideas.
 
Best regards,
Cliff

[edit, a little later]
I hooked up the transformer directly to the mains, without X10 components. Input = 122.6VAC, output = 12.5VDC. And its breaker did NOT trip. So that seems to rule out #1. And maybe #2.

Then I set things up using the basic lamp module, LM465. It behaved identically, that is, perfectly, up to just before the brightest dimming step; then the transformer input breaker tripped in the same manner. I'm kinda dismayed that the "pro" version, specifically designed for inductive loads, didn't do any better than its little brother.

[Brian H]

Welcome to the X10 Forums.
Yes you picked the correct section.
1. No I don't know the exact tolerance but 122.6 volts is not too high. My home runs that high most of the time.
2. Probably not too sensitive. Because the transformer is humming and the AC Voltage is going down. I wounder if at 100% On. The triac in the XPDI3 is only firing on half the AC input and a DC component is on the transformer.
3. The XPDI3 has Soft Start and Preset Dim features. Make sure it is set to 100% when all the way On.

There is one other possibility. Some combinations of X10 or X10Pro modules and some dimmable model transformers. Just don't get along together.
Since you seem to know some electrical stuff. Any chance you could as a test wire a 120 volt incandescent bulb across the dimmable transformers 120 volt input and see if anything changes?

[CliffyJ]

Thanks Brian for your thorough and rapid response.

About the Soft Start and Preset Dim features, I'm not aware of any other means of setting to 100% than the paddle and the remote controller. Is there something else to look for, some hidden pot, or command sequence?

I hooked up a 5w incandescent bulb at the xformer's input / XPDI3's output. You got my heart beating fast, I had my hopes up when going to that last "brightening" step, haha! But unfortunately, the hum happened, and the breaker tripped.

About that hum, it's not ramping up with the dimming. It comes on suddenly at that last step, just prior to the tripping. For maybe a second. I'm not sure whether it's coming from the transformer, breaker or the rectifier.

BTW, as you probably know, the XPDI3's spec sheet says: "It can handle...  Low Voltage Lighting using Inductive Transformers," which is what this is. I've tried different 12v kinds of loads on the transformer (including no load), but the thing always trips at that last step. The other thing that really surprises me is that the XPDI3 performed identically to, and just as poorly as, the LM465 -- which isn't supposed to handle this kind of thing.

[Brian H]

The Soft Start and Preset Dim level are set with the paddle as the instruction indicate.
No hidden pots or command sequence.

X10 Wiki page for the XPDI3.
Indicates maximum inductive load as 4 amps.
http://kbase.x10.com/wiki/XPDI3#Specifications

I will see if I can find anything else out.
I am sure other seasoned X10 users will have more information for you.

[JeffVolp]

How much load (DC current) is on the transformer?  Is it possible that at the max setting you are just pulling more than the transformer is designed to deliver, and hence the circuit breaker pops?

If not, and the fact that the transformer hums, I suspect it may be DC unbalance from not totally symmetrical switching causing core saturation and excessive current in the primary.  Unfortunately, there isn't any easy fix for that.

Jeff

[dhouston]

If not, and the fact that the transformer hums, I suspect it may be DC unbalance from not totally symmetrical switching causing core saturation and excessive current in the primary.  Unfortunately, there isn't any easy fix for that.

Jeff is probably on the right track as the XPD13 product description says,

Magnetic transformer loads usually do not generate noise, but may generate hum with some fans or motor loads. Unfortunately, there is no way to determine whether hum will occur without actually trying it. But, if unacceptable hum occurs, use the XPS3 wall switch module to provide X10 ON/OFF control only.

[CliffyJ]

How much load (DC current) is on the transformer?  Is it possible that at the max setting you are just pulling more than the transformer is designed to deliver, and hence the circuit breaker pops?
If not, and the fact that the transformer hums, I suspect it may be DC unbalance from not totally symmetrical switching causing core saturation and excessive current in the primary.  Unfortunately, there isn't any easy fix for that.
Jeff

The test load has been 4 watts. But the identical tripping phenomenon occurs without the load.
Thanks,
Cliff

[Brian H]

I suspect your transformer is not compatible with the XPDI3.
Some are not as pointed out.

[CliffyJ]

I suspect your transformer is not compatible with the XPDI3.
Some are not as pointed out.

I won't disagree. I was just hoping that, because the hum / tripping only happens in that last 5% (if that) of up-dimming (and no-where else on the dimming curve), thereby being an issue on the XPDI3 side, there would be some sort of workaround.

Thanks everyone for your assistance. 

If anyone has successfully used any outdoor landscape lighting transformer with the XPDI3, as the XPDI3's spec sheet describes, I'd be grateful to know of the make/model. Mine was specifically described as dimmable, btw.

Cliff

[Brian H]

Does the transformers manufacturer specify a type of dimmer or have a list of tested with dimmers?

[dave w]

At full ON the output from the XPI3 should be at it's cleanest output and the least hum, not the greatest hum.  Since the hum increases at the last step and a LM465 performs the same I am wondering a couple of things. The XPDI3 "should" have a snubber network across the triac to help it fire properly with large inductive loads. So I wonder if the XPDI3 might not have a problem. Next thought is,  are you sure the neutral line in the XPDI3 wall box is good? I suppose it must be, although the XPDI3 (AFAIK) is a modified WS467/WS12 so it might work without a neutral.

You could also, for giggles, add a 100W incandescent bulb along with the transformer just to see if the bulbs resistive load might help. Obviously you don't want a 100W bulb in the circuit all the time, but it would point to a compatibility problem.

FWIW
Years ago I had "Malibu" palm tree, up lights, made from four automotive high beam head lights driven by a 10 amp transformer. I "dimmed" the transformer with a standard 500W wall dimmer fed from an Appliance Module.  I noticed the transformer behaved the best, ran the coolest and hummed the least when the dimmer was a GE model. Also the GE didn't blow out when Florida Flicker and Flash power suddenly tripped off. The no name dimmers always popped the triac from the inductive kickback off the transformer.  I guess that means GE used higher PIV triacs and maybe installed snubbers in their dimmers(?).  

[CliffyJ]

Does the transformers manufacturer specify a type of dimmer or have a list of tested with dimmers?

Brian, I've looked hard for a landscape transformer manufacturer that approves any X10 dimmer. The ("dimmable") such transformer manufacturer I finally chose says (in reading the literature they sent with the device) use ONLY their (traditionally-controlled) dimmers. Of course they do. Even though this is a bare, wire-wound, inductive, non-electronic transformer, the kind that the XPDI3 lit says it should work with. 

Thanks for the question though, I hope I don't seem unappreciative. After weeks of expensive messing with this, the matter has become pretty frustrating to me, but I'm forced to find some solution. So thanks for any and all ideas.

Cliff

[CliffyJ]

At full ON the output from the XPI3 should be at it's cleanest output and the least hum, not the greatest hum.  Since the hum increases at the last step and a LM465 performs the same I am wondering a couple of things. The XPDI3 "should" have a snubber network across the triac to help it fire properly with large inductive loads. So I wonder if the XPDI3 might not have a problem. Next thought is,  are you sure the neutral line in the XPDI3 wall box is good? I suppose it must be, although the XPDI3 (AFAIK) is a modified WS467/WS12 so it might work without a neutral.

You could also, for giggles, add a 100W incandescent bulb along with the transformer just to see if the bulbs resistive load might help. Obviously you don't want a 100W bulb in the circuit all the time, but it would point to a compatibility problem.

Brian had suggested the load bulb, and I tried that -- a 5 watter. Big I figured WTH. So I put in a 75w bulb, and...

IT WORKED!!

That is, at the paddle, all dims perfectly -- 75w load bulb, transformer + 12v 4w LED bulb, no hum, no tripping, up and down. Awlsome dudes!!
 
Except that now the XPDI3 won't respond to the PalmPad, for love or money, even though the receiver bang-bang is responding just fine. I've checked the batteries, even moved the receiver to the same plug strip as the XPDI3's input, no joy. I hate to open a new thread on this, we're so close!!

But anyway, the answer was: Stupid me in my test setup, I wasn't putting enough load on the XPDI3. So thanks Brian, and Dave, for helping me to get to this point.

[edit] It's now easy to see that this is a load issue. I have a switch on my load bulb; and can flip it on and off. On = no issues; off = sudden hum+trip at the final step. At least, as far as paddle-op goes.

[dave w]

Except that now the XPDI3 won't respond to the PalmPad, for love or money,

Did the XPDI3 work from the Palm Pad before the 75watt bulb?

Does it work without the transformer (only the 75W bulb as load)?

BTW the answer to tripping breaker might be loading up the output of the transformer.

[CliffyJ]

Except that now the XPDI3 won't respond to the PalmPad, for love or money,

Did the XPDI3 work from the Palm Pad before the 75watt bulb?

Does it work without the transformer (only the 75W bulb as load)?

BTW the answer to tripping breaker might be loading up the output of the transformer.

I tried it before, numerous times, with and without the load bulb.

But, since you asked, I tried once more. And...

IT WORKED!!

Dimming from the pad, it's working great! Maybe the XPDI3 needed to cool down or reset or something?

I'm now blind from watching the bulb, but who cares! 

Thanks Dave,
Cliff