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[Towertalk] Motor Start Capacitors

To: <>
Subject: [Towertalk] Motor Start Capacitors
From: (Joe)
Date: Wed, 14 Aug 2002 23:22:36 -0500
----- Original Message -----
From: "Joe" <>
To: <>
Sent: Thursday, August 08, 2002 3:22 PM
Subject: Motor Start Capacitors

> While this is nothing new to many of you, there are a number of real
> advantages in putting the motor start capacator on the tower at the
> First of all, that's where it ought to be.  Check most any industrial
> electric motor installation and you will find the motor start capacitor on
> or near the motor itself.  Putting it several hundred feet away is hard to
> justifiy in so far as good engineering practice goes.
> Second, many users think that the "black and white" wires (Terminals 1 &
> are the primary motor current carrying wires ... otherwise why  would they
> be of a heavier gage.  Wrong ... these two wires simply provide currrent
> the brake solenoid.  The current to the motor windings uses only one of
> these wires along with two of the other smaller gage wires.  By freeing up
> two of the wires in the normal 8-conduction rotor cable by putting the
> start capacitor on the tower, it allows the two extra wires to be
> with the "return" leads from the two motor windings, which reduces power
> loss and assists the motor in turning more reliably.
> Finally, capacitors designed for use with industrial motors are very
> The ones that  come from a source like Gainger are expected to live in the
> cruel, harsh external world.  (Go look at you outside A/C unit's fan motor
> cap.) If properly installed, they will outlast most amateur antennas.
> had them on towers for over 15 years with no failures.
> We took care to use quality stranded electrical wire and to ":pot" the
> connections with electrical quality RTV. They are mounted with the
> connections down and placed just beneath the rotor plate.  It's worked for
> us.
> Joe, W5ASP

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