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David Gretzmier
06-10-2010, 11:50 PM
how much unloaded and how much at 80% load?

OK, I have installed more than a few trans, and I want this thread to be kinda of a poll of what you guys expect out there, and what is out of bounds. I have seen input voltage at the plug anywhere from a very low of 102 volts to a fairly high of 125 or so, but 90% of the time I see 110 to 120.

I installed 3, 900 watt trans from Garden Light the past week, 12-15 volt, same job, all imput voltages from 115 to 118 on 3 different breakers on GFCI outlets outside. I am pretty sure these are made by jefferson, I may be wrong on that, but they look identical to the coppermoon units.

my experience with these units is at 115 volts and up imput, they tend to test out unloaded at about 15.2-15.5 or so on the high tap and come down to 14.5 or so loaded up to 80%. This is fine with me on most jobs, as with a 3 volt drop I can design around 10 and 12 guage, 100-120 foot runs and 80-120 watt loads per run, and be able to add a light to a run if the customer wants to add after we're done and they see it.

So imagine my surprise on all 3 units starting unloaded at 14.5-14.6, and 70-80% loaded dropping to 13.3-13.6. Luckily I tend to over use wire and under load said wire, so it was fine, but barely, and no real room to add lights on most runs.

I am used to seeing a volt drop or so on loading, but not starting voltage on a new trans already down a half a volt unloaded, unless starting voltage is 105 or lower. What do you guys see out there and what is "right?"

Alan B
06-11-2010, 01:01 AM
I'll load up a couple tomorrow and give you a reading from several different transformers and post.

It has never been an issue to us or our customers because all Volt transformers have taps up to 22v. If you need more voltage/longer runs, you have higher taps. Yes there are the 1838 conformists but I don't want to derail your specific question.

Sincerely,

Alan

David Gretzmier
06-11-2010, 08:28 AM
Thanks Alan. I will say the Volt name brand transformers I have installed start out around 15.5 or so on the 15 volt tap as I recall and then come down around a volt as I mentioned. and no problems with them so far. but even if I had larger taps to grab, it still seems silly to grab a 14 volt tap for the fixtures right next to the trans to get 11.6 volts. the 12 and 13 volt tap were not even used.

Thanks for testing yours and getting back to me. If you could, list the imput voltage loaded at 80% and unloaded. I forgot to mention that the input voltage did drop to 111 volts from 118 once the trans was loaded.

And I would thank folks in advance to not make this a Garden Light bashing thread, a made in china bashing thread, or a "why I don't have this problem because I only do LED" thread.

Just keep it simple and nice. I'd just like folks to name the brand of trans they most often use, and what do you expect a trans to read on the taps loaded and loaded versus the imput voltage.

steveparrott
06-11-2010, 12:30 PM
David,

A few years back, our engineers did a study comparing a CAST 1200W toroidal transformer with a 1200W EI laminated type. The test looked at several variables including voltage drop when any single voltage tap was loaded to 100% of transformer's rated wattage. Read the article (http://www.cast-lighting.com/learning/articles/product-information_article_Low-Voltage-Lighting-Transformer-Comparison).

Voltage drop at the secondary under load is primarily due to winding resistance in the core. This resistance leads to heat generation and subsequent loss of energy. The hotter the transformer the greater the voltage drop under load at the secondary.

EI-type transformers generate more heat in the core and will always have a greater voltage loss under load. Comparing various toroidal models will also reveal differences due to the quality of toroidal components and construction.

Our test with the CAST transformer showed a voltage loss under full load to vary from 0.5V (12-volt tap) to 0.85V (17-volt tap). The 15V tap lost 0.75V.

Alan B
06-11-2010, 01:08 PM
Steve,

Well said and thank you for the post (it's always a plus when one sponsors studies supports both sponsors products).

To engage in shameless promotion-- all Volt transformers have toroidal cores. They also all go to 22 v.

Have a great weekend everyone!

Sincerely,

Alan

JoeinJasper
06-11-2010, 01:19 PM
A question from a student of the art and science of lighting...If by some freak of design, all the home runs need to come off of a single tap, do you split the load evenly on the commons and put all of the load on the one lug? Or do you redesign so that multiple volt taps can be used?

Joe

S&MLL
06-11-2010, 09:03 PM
That depends if the tap can be loaded to 100 percent. If so go for it run it all on the 12v. Then split your commons. But if the 12v tap cant handle 100 percent load.... Well you shouldnt be using such a cheap transformer

David Gretzmier
06-11-2010, 09:49 PM
excellent artile steve. thanks for chiming in. like the article state, it has always seemed as though taps usually start high and then sink more. and in this case, they started low, and well, sank more.

anyone else want to chime in on taps and expectations from different trans? Any q tran or gambino followers want to report what they are finding when checking loaded and unloaded?

Alan B
06-21-2010, 04:20 PM
Here are the results from the Volt Transformers:

Outlet voltage measured: 122v

TAP:..................12v 13v 14v 15v 16v 17v 18v 22v
No Load Voltage: 12.2 13.2 14.2 15.2 16.2 17.3 18.3 22.3
83% load (250w) 11.7 12.7 13.6 14.5 15.4 16.4 17.3 20.8

Out of curiosity I tried at full 300w per tap (over amping all taps except the 12v tap-- i.e. expected all taps above 12v to trip) but got the following:
100% load (300w) 11.7 12.6 13.4 14.3 15.2 tripped tripped tripped

Summary: The Volt transformers with 250w on any one tap only had a .3 to .7 drop between the 12v to 15v taps.

Similar/same results as Steve published for Cast's Toroidal model. As Steve explained, Toroidal core transformers are more efficient, run cooler and thus have less voltage drop when loaded. In addition they never buzz. In the rest of the electrical industry, Toroidal core transformers (for all applications) are undisputed, as the superior core to laminated magnetic. Toroidals are known to last longer as well (less heat, more efficient).

As far as I know, Volt is the only brand of Landscape Lighting transformers that ONLY uses toroidal cores in all our transformers. If I'm not mistaken Cast and Kichler offer toroidal, but only in there top of the line models.

Sincerely,

Alan

steveparrott
06-21-2010, 04:47 PM
A question from a student of the art and science of lighting...If by some freak of design, all the home runs need to come off of a single tap, do you split the load evenly on the commons and put all of the load on the one lug? Or do you redesign so that multiple volt taps can be used?

Joe

CAST transformers can carry 100% of the load on any single voltage tap.

steveparrott
06-21-2010, 04:53 PM
Here are the results from the Volt Transformers:

Outlet voltage measured: 122v

TAP:..................12v 13v 14v 15v 16v 17v 18v 22v
No Load Voltage: 12.2 13.2 14.2 15.2 16.2 17.3 18.3 22.3
83% load (250w) 11.7 12.7 13.6 14.5 15.4 16.4 17.3 20.8

Out of curiosity I tried at full 300w per tap (over amping all taps except the 12v tap-- i.e. expected all taps above 12v to trip) but got the following:
100% load (300w) 11.7 12.6 13.4 14.3 15.2 tripped tripped tripped

Summary: The Volt transformers with 250w on any one tap only had a .3 to .7 drop between the 12v to 15v taps.

Similar/same results as Steve published for Cast's Toroidal model. As Steve explained, Toroidal core transformers are more efficient, run cooler and thus have less voltage drop when loaded. In addition they never buzz. In the rest of the electrical industry, Toroidal core transformers (for all applications) are undisputed, as the superior core to laminated magnetic. Toroidals are known to last longer as well (less heat, more efficient).

As far as I know, Volt is the only brand of Landscape Lighting transformers that ONLY uses toroidal cores in all our transformers. If I'm not mistaken Cast and Kichler offer toroidal, but only in there top of the line models.

Sincerely,

Alan

Alan, a little confused by your test condition statements about 100% load equaling 300W. That's true for the commons but not the voltage taps. Did you test, for instance, 1200W load on each voltage tap for the 1200W transformer? That would replicate the CAST study conditions.

By the way, all CAST transformers (with the exception of the electronic mini's) are toroidal.

Alan B
06-21-2010, 05:40 PM
Alan, a little confused by your test condition statements about 100% load equaling 300W. That's true for the commons but not the voltage taps. Did you test, for instance, 1200W load on each voltage tap for the 1200W transformer? That would replicate the CAST study conditions.

By the way, all CAST transformers (with the exception of the electronic mini's) are toroidal.
Steve,
For the above, we took a 300w trans, put 300w on the common and 300w on the 12v tap and measured the 12v tap with and without the full 300w load on it. Then disconnected from the 12v tap and instead moved all 300w to the 13v tap and so on. In each case we whatever was on the common (the 300w load test or 250w load test) we would also put the entire load onto 1 tap and measure that taps performance.

Also did this with a 600w transformer, but instead had 300w on Common 1 (maxed out) and on the 12v tap, and 300w on Com2 and put the other side on the 13v tap. So that we could both max out the trans commons and put a heavy load on the taps.

Thank you very much for the clarification about Cast's Toroidals. I don't know if I misread or your site info has been updated, but I was under the impression that only your Master Series was toroidal. My sincere apologies. I could have sworn that it when I was reading about your diff models on your site (year ago) that it used to mention toroidal as a feature for your master series but not on the other models. My apologies.

Sincerely,

Alan

David Gretzmier
06-21-2010, 08:41 PM
super info guys ! this is why folks choose to buy transformers or not- do they hold up under voltage and what should folks expect. Alan, any chance you could do some tests on a lower imput voltage? I usually see 110-118 volts, as opposed to 122 volts. also, curious on larger trans, 900w and 1200w, is voltage drop a factor of imput voltage dropping or just transformer loss. if you have a 9v imput drop, say, from 121 to 112 under load, do the taps drop the same percentage ?

steveparrott
06-22-2010, 08:08 AM
super info guys ! this is why folks choose to buy transformers or not- do they hold up under voltage and what should folks expect. Alan, any chance you could do some tests on a lower imput voltage? I usually see 110-118 volts, as opposed to 122 volts. also, curious on larger trans, 900w and 1200w, is voltage drop a factor of imput voltage dropping or just transformer loss. if you have a 9v imput drop, say, from 121 to 112 under load, do the taps drop the same percentage ?

Theoretically, the secondary output voltage is directly proportional to the input voltage; so, for example 120V:12V, 110V:11V.

This, however, does not take into account the fact that transformers operate much more efficiently at higher input voltages than lower ones. When you raise the voltage, it lowers the amperage (A=W/V). This, in part, is why transmission lines operate at extremely high voltage; and why standard voltage in most countries has been set at 220 or 240V.

When you lower the input voltage on a transformer, the amperage increases along all the wires in the core; the core temperature increases; wire resistance increases; and as a consequence both efficiency and regulation suffers.

The bottom line is that reducing the input voltage to 110V probably reduces the output voltage to slightly less than 11V and the voltage drop under load will be about the same or slightly greater than at 120V.

A toroidal transformer's ability to regulate voltage and operate efficiently (under reduced voltage and heavy loads), is largely dependent on the quality and gauge of core wire and on the mechanics of core construction.

In the construction of CAST toroids, we have over-specified wire gauge and construction parameters in both the core and in the wires that bring power to the secondaries. That's why CAST transformers are a little more expensive. The benefits are better regulation, better efficiency, and lower operating temperatures. Not all toroids are created equal.

Alan B
06-22-2010, 01:08 PM
super info guys ! this is why folks choose to buy transformers or not- do they hold up under voltage and what should folks expect. Alan, any chance you could do some tests on a lower input voltage? I usually see 110-118 volts, as opposed to 122 volts. also, curious on larger trans, 900w and 1200w, is voltage drop a factor of imput voltage dropping or just transformer loss. if you have a 9v imput drop, say, from 121 to 112 under load, do the taps drop the same percentage ?

David,
No problem, thanks for letting us point out the great performance and comparative advantages.

Our office, warehouse and testing area all have 122v coming out of the walls, we'd have to find another location with lower wall voltage for your test. It's a straight (and very accurate) 10:1 transformer.
122v gave 12.2 at 12 v tap,
if you start with 110 wall voltage, you'll get 11v out of the 12 v tap (exactly 1/10thof the wall voltage).

So far only tested the 300w and 600w. Will test the 900 and 1200 when we get a chance. The Volt 900w and 1200w trans weigh 47 lbs and 50 lbs respectively-- they are heavy weights with a lot of copper in the toroidal core.


-The wall outlet measure 122.2 (to be exact) with no load. When we turned on the 600w transformer fully loaded, our wall receptacle dropped exactly 1 volt from 122.2 to 121.2 (extra load on the wiring in our office wall outlet-- voltage drop occurs with 120v wiring as well). Since the input voltage from our office wall receptacle dropped 1 volt then the transformer secondary would drop .1 v as a result.

Summary: In the end with all the test thus far, for all practical purposes, regardless of tap or load, the most drop on the Volt transformer you'll see is in the tenths of a volt. It's just not an issue that affects installations when using our transformers.

Sincerely,
Alan

wbaptist
06-22-2010, 07:05 PM
I will like to perform the same tests to a Unique Lighting Transformer. I just have a couple questions. When doing these tests are you checking the voltage at the lamps to make sure they are correct? How long is the wire run between the transformer and the 1200 watt load? Are you simply taking 35 35watt lamps to get 1200 watts?

Thanks for the help guys. As soon as I get the info I will perform the tests. I have a number of other brand transformers on my training wall I could test them all the same way using the same power source.

steveparrott
06-23-2010, 04:12 PM
I will like to perform the same tests to a Unique Lighting Transformer. I just have a couple questions. When doing these tests are you checking the voltage at the lamps to make sure they are correct? How long is the wire run between the transformer and the 1200 watt load? Are you simply taking 35 35watt lamps to get 1200 watts?

Thanks for the help guys. As soon as I get the info I will perform the tests. I have a number of other brand transformers on my training wall I could test them all the same way using the same power source.

We make a transformer test stand (http://www.cast-lighting.com/products/tools/testing-tools/139/) that is basically an aluminum bench with (20) MR-16 sockets attached. They are grouped in 4's to provide (5) wire runs with various loads. We supply these to our distributors so they can troubleshoot transformers under full load.

I'm not suggesting you purchase this item, but you could improvise, buy (16) cheap MR-16 sockets and an equal number of cheap 75W lamps. Gang them 4to a 10/2 wire.

You're right to ask about voltage at the socket. When testing the higher taps, you're liable to blow out the lamps. In our published study, lamps were not used, but rather a resistive load that delivered 1200W equivalent for each tap (measured with an ampmeter). You can add long coils of thin gauge wire to bring socket voltage down (just don't burn down the house - that wire will burn up eventually). Also keep in mind the higher taps will require less lamp wattage since you'll be adding wire resistance. You can estimate the lamp wattage/wire length required to produce the 1200W equivalent with our system calculator (http://www.cast-lighting.com/support-installers/system-calculator-installers/).

For example, 300 lamp watts on 20 ft. of 16/2 has a 4 volt loss. It's total watts (lamps and wire) = 400W. It will need to be connected to the 16-volt tap to bring 12V to the sockets. Three of the above configurations would simulate a total 1,200W load.

Sounds complicated and expensive, good luck.