[TowerTalk] Rotator Lightning Protection

[Paul Christensen]

Good advice, Joe.  For now, I'm inclined to isolate circuit ground from 
chassis ground on the secondary side of the controller's power transformer. 
Of course, there's no guarantee during a strike event that a ground path won’t 
be created that would undermine this isolation.

Paul, W9AC

-----Original Message----- 
From: Joe Subich, W4TV
Sent: Friday, May 15, 2015 12:17 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Rotator Lightning Protection


I'd be most tempted to install contactors in both "rotate"
leads that were only closed when turning the antenna.  Consider
making your "common" disconnect a three pole device.

73,

   ... Joe, W4TV


On 2015-05-15 11:15 AM, Paul Christensen wrote:
> Jim,
>
>> "what about mechanical limit switches on the rotator motor?"
>
> A possibility but that's probably best done when these units are back on
> the ground for service.  That shouldn’t be for quite a long time.
>
>> "Since it's a DC motor, you put a diode in series with each of the two
> switches, which are then paralleled."
>
> Maybe I'm just being dense this morning, but I don’t see how a
> series/parallel diode combination helps in this case.  I just drew-out
> the electrical diagram but don't see how the diode would limit current
> during an MOV fault while still allowing rotator current during a normal
> turning operation.
>
> A bit more info:  The prop pitch uses two windings: one for CW and the
> other for CCW.  A common lead connects to the ends of each and
> ultimately, this common lead routes to the controller's MOSFET.  The M2
> controller uses a P&B frame relay that directs +48V to either the CW or
> CCW winding, depending on the called direction.  The relay's NC contacts
> are on one or the other windings.  I forgot which.  But the MOV failure
> would result in current in this NC winding since its connected to +48V
> via the NC relay contact.
>
> Paul, W9AC
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk