RE: [CAD_CAM_EDM_DRO] Series I followup

The current rating of a transformer is a function of the wire size used to
wind it, not the voltage at which it is run. Let's assume the easiest
example first: A transformer consisting of two windings. A primary rated at
240 Volts Input and a secondary rated at 120 Volts. The secondary is rated
for 10 amps. If you run this transformer at 240 volts input, you have a 2.4
KVA transformer (240 volts multiplied by 10 amps) If you choose to run this
transformer at only 120 volts input, you have a 1.2 KVA transformer (120
volts multiplied by 10 amps).

In the next example, we will take a transformer with two primary windings
and two secondary windings. This is typical of many industrial transformers.
Assume that each of the four windings is rated at 120 volts and 10 amps.

You can connect the two primary windings (generally labeled H1 and H2) in
series to use an input voltage of 240 volts. You can connect the secondaries
(generally labeled X1 and X2) in parallel to get an output voltage of 120
volts at 20 amps. You could also connect them in series to get an output
voltage of 240 volts at 20 amps. You can also connect the two primary
windings in parallel for an input voltage of 120 volts. With this
configuration, connect the two output windings in parallel for 120 volts at
20 amps or in series for 240 volts at 10 amps. Connect the two primary
windings in series and use an input voltage of 120 volts and you can connect
the two output windings in parallel for an output voltage of 60 volts at 20
amps.

The only thing you can't do is connect the two primary windings in parallel
and use an input voltage of 240 volts. Doing this would most likely saturate
the transformer core and cause a high current to flow in the primary until
either a fuse blew or the transformer overheated and started burning itself
up.

-- Carol & Jerry Jankura
Strongsville, Ohio
So many toys, so little time



-----Original Message-----
From: Vlocci [mailto:VLOCCI@...]
Sent: Sunday, May 06, 2001 5:46 PM
To: cadcam
Subject: [CAD_CAM_EDM_DRO] Series I followup

With a 240 volt input it is good for 15 amps. I
could always run it on 120 volts input, but I'm not sure if 7.5 amps will be
enough output. (which leads to my next question) I'm assuming the benefit
of these 160 volt drives comes from increased speed?