3 Oct
2008
3 Oct
'08
3:28 p.m.
On 3 Oct 2008 at 21:29, Tony Duell wrote:
I am suprised that motors objected to too low a
voltage. Wasn't there a
frequency difference too -- I thought that some of Japan was 50Hz. That
might have been more of a problem
Induction motors run on too-low voltage tend to draw too much
current, leading to overheating, particularly in those applications
where a more-or-less constant load that runs the motor near its
nameplate rating is encountered. You can sometimes find under-
voltage protection devices on industrial equipment motors. Many
small motors are impedance-protected, so operating, say, an equipment
cooling fan motor on low voltage is probably safe.
On the other hand, I've run 220v 25Hz induction motors on 120v 60Hz
just fine--or at least they didn't burn up.
I'd seen 45V batteries listed, but I assumed
(incorrectly, I guess) that
they were normally used in pairs to give 90V. I've never seen a radio
that used them, I do have one device, totally off-topic, that should use one.
The 45v batteries were widely used in photoflash units, as well as
some early portable radios. 67.5 and 90v batters were also used here-
-and then for photographic strobe applications, 225, 450 and 510v dry
batteries for very fast recovery times. 510v was the highest-voltage
widely-available primary battery that I'm aware of.
Cheers,
Chuck