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Re: [TowerTalk] CAT 5 as Rotator cable, sprinkler wire

To: "Jim Brown" <>,"Tower Talk List" <>
Subject: Re: [TowerTalk] CAT 5 as Rotator cable, sprinkler wire
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Sat, 19 Jun 2004 10:17:11 -0400
List-post: <>
> wire sizes, use your VOM to measure the current with a
short cable connecting
> the rotor to the controller (or look at the manufacturer's
specs for current), and
> use Ohm's law.

If you are going to measure voltage and current, use a
storage scope. Measure under the worse-case load conditions
when the motor is at maximum torque. Also be SURE the
manufacturer did that also!!!!

MANY manufacturers rate for typical currents while running
and not starting currents, they often don't publish peak and
worse-case currents, and sometimes they even miss entirely
on electrical specs.

While we often get away with very small conductors in a
short run with light rotor loads, I'd be a little reluctant
to get down near the edge. There always is some possibility
a light gauge conductor may not be good for the rotor or
control equipment, and it might be frustrating if you need
to move the antenna in a windstorm.

A good manual would describe minimum conductor gauges, but I
suppose they are not all good. In any event, picking
absolute conductor size in a motor system based on just
measuring run voltage or current without measuring MAXIMUM
current and knowing the minimum allowable voltage in worse
case conditions is a pretty sorry way to do things.

73 Tom


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