Message-ID: <003101c3ca7f$42d94b20$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <6.0.1.1.2.20031224113817.0381be40@POP3.freeler.nl> <004101c3ca6c$58838980$5ace28c3@erica>
Date: Thu, 25 Dec 2003 00:34:25 -0000
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Subject: LF: Re: Re: Rope
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Hi both, could I ask if the said insulator is fitted with an "anti-corona"
ring. Severe changes in direction of the wire can produce quite high voltage
gradients, even when not at the end of the run. Another thought is to series
connect....ie put a "egg" in the short rope length. This will be effective
if it is a "leakage" current but not if it is corona, which can act rather
like a small blow-torch. This is why it pits the surface of the insulators.

Cheers and Happy Christmas de Alan G3NYK
alan.melia@btinternet.com

----- Original Message -----
From: "g3ldo" <g3ldo@ukonline.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: 24 December 2003 22:17
Subject: LF: Re: Rope


> Dick Rollema said
> -----------------------
> Starting transmitting the aerial ammeter swayed wildly and I heard a
> disturbing noise outside. It appeared that one half of the aerial had come
> down.
> It turned out that one hoisting  rope had been burned through where it had
> passed the pulley.  Between the pulley and the "pyrex"  insulator had been
> some 15cm of rope. But it had been raining for several days and the rope
> bust have been soaking wet. See the attachments; the top end of the rope
was
> on the pulley
>
> I intend to replace the rope and to insert extra ceramic insulators of the
> dog bone type as I have supplied to several British amateurs (they come
from
> the closed down  "Radio Kootwijk" commercial  PTT-station).
>
> -----------------------
>
> I have had this trouble even when using Dick's "Radio Kootwijk"
insulators.
> It only seems to happen where there is a short length of insulated rope
> between the insulator and the support. What seems to happen is that the
> insulator eventually becomes dirty (in my case covered with a thin film of
> salt). This, together with wet weather conditions, produces a conduction
> path that can carbonise the short rope support. The fix is to use copper
> wire between the insulator and the support fixing point.
> After a storm at sea I have seen blue spark tracts running along the salt
> coated insulator but this arrangement has not failed. However the
insulator
> should be cleaned because such sparking causes minor damage to the surface
> of the insulator.
>
> The problem reported by Dick doesn't seem to happen where there is a long
> rope from the insulator to the support structure.
>
>
> Peter, G3LDO
>
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