Paul Furman wrote:
Mmmm there must be some distinction. Can you clarify? All I get is that
my info was wrong but I don't know anything further.
What is the significance of a hertz?
Hertz, a proper noun, is the SI (International System of Units) unit for
frequency named for Heinrich Rudolf Hertz.
http://www.ideafinder.com/history/inventors/hertz.htm
What is the difference between the large and small transformers?
Solid state?
The difference is the size, and possibly the amount of power that can be
handled by one vs. the other. There is no such thing as a sold state
transformer. Look at a dictionary for the definition of the word
"transformer."
How closely should the wattage match?
The "wattage" specified on a transformer is the maximum that can be
handled. Lower loads are no problem.
I may have several fixtures on one
transformer and switch them separately. Is it necessary to have a bunch
of 60w transformers switched on the 120v side?
No.
EL wrote:
Paul Furman wrote:
EL wrote:
Paul Furman wrote:
...transformer for my low volt garden lighting. Here's what I learned:
The small (size of a pack of cigarretes) $25 12v transformer is an
ELECTRIC transformer that must be
mounted indoors and is easily damaged by moisture, the large (size
of a shoebox) $100 12v transformer is a MAGNETIC transformer
suitable for mounting outdoors and
more weather resistant.
All 60 Hz transformers are magnetic.
What does 60 Hz mean? Both types are 60 Hz.
60 Hz is the abbreviation for 60 Hertz (formerly 60 cycles per second)
the frequency at which the voltage alternates polarity. Magnetics are
electric.
I got my info from chatting with the manufacturer's tech support guy
on the phone. (small electronic transformer) American-De Rosa Lamparts.
The reason the small one blew my breaker is because the small wires
go to the 120v
wall plug & the fat wires go to the 12v lighting. The smaller
voltage is
more sensitive to voltage drop thus the larger wires. The 120v
leads were really skimpy, less than most electric appliances.
The lower voltage (12 volt) wires are larger diameter because they
have higher current in them than the 120 volt wires. Almost 10
times as much current.
They said the power usage when the transformer is plugged in is
trivial so it's not really necessary to switch the 12v side.
Not necessarily true for inexpensive transformers. Feel the case
when it has been plugged in for a while with no load and see if it's
warm. If it is the current isn't trivial. Most inexpensive
transformers will have fairly high magnetizing currents. This is
largely reactive current, but it's still current and is still going
to result in core losses and resistive losses in the winding...all
these losses are real and cause heating.
Maybe he exaggerated. Its running with a load and just slightly warm
now. The magnetic one gets more warm with no load. So is the electric
one a poorer quality? Wastes energy, dies younger?
Both are electric. Nothing you've said indicates the quality of the
unit. The distinction between "magnetic" and "electric" is not there.
By definition a transformer is magnetic. It is also electric. Energy
from one port is coupled to the other by means of a magnetic field.
The heating of the larger transformer under no-load conditions is
because of the magnetizing current. This heating is frequently
significant in a cheap, not necessarily inexpensive, transformer.
Having a too-small transformer isn't a big problem, no loss of
efficiency
Not true.
?
but if you only have say 10 watts of lights on a 150w
transformer it might provide irregular supply
No.
?