I'm looking for some MR16 recessed swivel lamps. For installation in an
existing ceiling a shallow remodel housing for remote transformer makes for
the easiest install. But do I want a magnetic or electronic transformer? I
don't plan to dim.

Don www.donwiss.com (e-mail link at home page bottom).

"Don Wiss" wrote in message
news
I'm looking for some MR16 recessed swivel lamps. For installation in an
existing ceiling a shallow remodel housing for remote transformer makes
for
the easiest install. But do I want a magnetic or electronic transformer? I
don't plan to dim.

Don www.donwiss.com (e-mail link at home page bottom).

As long as you don't plan to dim, I'd get whatever is cheaper. Magnetic is
going to be heavier

On Sun, 06 Apr 2008 17:19:30 -0400, I wrote:

do I want a magnetic or electronic transformer?

I found this:

MAGNETIC TRANSFORMERS operate at standard low frequencies (5O/6O Hz). They
offer very reliable operation and are very durable, Since magnetic
transformers operate at low frequencies, they experience much less vo1tage
drop over a long distance compared to high frequency electronic
transformers. For optimum performance, all our magnetic transformers must
be loaded to a minimum of 80% of the transformers maximum output wattage.
For example, a 300W transformer must be loaded to a minimum of 240W in
order for the output voltage to be equal to or less than 12VAC. Otherwise
the output voltage will be greater than 12VAC and cause lamps to burn out
prematurely. All Fusion magnetic transformers are designed to carry a full
load.

ELECTRONIC TRANSFORMERS are very compact and much smaller than their
magnetic counterparts. They provide built in protection against electrical
shorts applied at the outputs and to the lighting system, In order for
electronic transformers to operate properly, the output must be loaded to a
minimum of 50% of the rated wattage of the transformer. Any output load
below 50% may result in lamps flickering and premature lamps burning out.
Since electronic transformers operate at much higher frequencies, most
standard volt and amp meters intended for 6Ohz type measurements cannot be
used to accurately measure the outputs of these transformers. To measure
the output, we recommend using a Fluke digital multimeter model number 189.

Electronic transformers may cause interference with appliances such as TVs
and radios. If interference is a problem, a line filter may be installed
either at the transformer or at the appliance input, Another option is to
use a magnetic transformer, which operates at a lower frequency and will
not cause any interference.

Don www.donwiss.com (e-mail link at home page bottom).

On Sun, 6 Apr 2008 17:34:49 -0400, RBM wrote:

Don Wiss wrote:
I'm looking for some MR16 recessed swivel lamps. For installation in an
existing ceiling a shallow remodel housing for remote transformer makes for
the easiest install. But do I want a magnetic or electronic transformer? I
don't plan to dim.

As long as you don't plan to dim, I'd get whatever is cheaper. Magnetic is
going to be heavier

As the transformer will be in a nearby closet the weight isn't of concern.
What is of concern is the load. I figure I will have five MR16s 32" apart.
I don't know just what wattage. My ceilings are 11 1/2'. I plan to wall
wash. I find 150w and 300w transformers. As you can see from my other post
each type has a different minimum load. If I go for 42w bulbs, the 210w
total is too low for a 300w magnetic transformer. But the electronic has
interference issues and at 15' for the furthest I would have to use really
heavy wire to not have a voltage drop.

Don www.donwiss.com (e-mail link at home page bottom).

"Don Wiss" wrote in message
news
I'm looking for some MR16 recessed swivel lamps. For installation in an
existing ceiling a shallow remodel housing for remote transformer makes
for
the easiest install. But do I want a magnetic or electronic transformer? I
don't plan to dim.

Don www.donwiss.com (e-mail link at home page bottom).



If these things are the same as ballasts for flourescent lights, go with
electronic bought from an electrical supply place, not Home Cheapo. They
don't buzz or hum and they run cool.

Don Wiss writes:

MAGNETIC TRANSFORMERS operate at standard low frequencies (5O/6O Hz). They
offer very reliable operation and are very durable, Since magnetic
transformers operate at low frequencies, they experience much less vo1tage
drop over a long distance compared to high frequency electronic
transformers. For optimum performance, all our magnetic transformers must
be loaded to a minimum of 80% of the transformers maximum output wattage.
For example, a 300W transformer must be loaded to a minimum of 240W in
order for the output voltage to be equal to or less than 12VAC. Otherwise
the output voltage will be greater than 12VAC and cause lamps to burn out
prematurely. All Fusion magnetic transformers are designed to carry a full
load.

Hmm. This says that the transformers have relatively poor regulation
due to high internal resistance, so output voltage drops with load, and
that they have compensated for this by making the open-circuit output
voltage higher. This probably does give the smallest, least expensive
transformer for a specific load that the transformer is matched to.
But the transformer is likely to run hot at that load.

I wonder if there are other suppliers that sell lighting transformers
whose open circuit voltage is just 12 V, with better regulation so the
output voltage falls less with increasing load. Such a transformer
could be used for any load, from a single lamp up to full rated output.
It would run cooler too, with lower losses at full load. But it will be
larger (larger diameter copper, or fewer turns of copper which requires
more iron) than the transformer with poorer regulation.

Dave

On 4/7/2008 1:02 PM Dave Martindale spake thus:

Don Wiss writes:

MAGNETIC TRANSFORMERS operate at standard low frequencies (5O/6O Hz). They
offer very reliable operation and are very durable, Since magnetic
transformers operate at low frequencies, they experience much less vo1tage
drop over a long distance compared to high frequency electronic
transformers.

[...]

Hmm. This says that the transformers have relatively poor regulation
due to high internal resistance, so output voltage drops with load, and
that they have compensated for this by making the open-circuit output
voltage higher. This probably does give the smallest, least expensive
transformer for a specific load that the transformer is matched to.
But the transformer is likely to run hot at that load.

I wonder if there are other suppliers that sell lighting transformers
whose open circuit voltage is just 12 V, with better regulation so the
output voltage falls less with increasing load. Such a transformer
could be used for any load, from a single lamp up to full rated output.
It would run cooler too, with lower losses at full load. But it will be
larger (larger diameter copper, or fewer turns of copper which requires
more iron) than the transformer with poorer regulation.

Regulation, schmegulation.

I wouldn't sweat that part of the equation; this is far from a
high-precision system, and a little variation, or even fluctuation, of
voltage isn't going to make any perceptible difference. The load, after
all, will be fixed, once the O.P. gets all the lamps installed, so a
common ordinary transformer will work just fine here.


--
The best argument against democracy is a five-minute
conversation with the average voter.

- Attributed to Winston Churchill