[Mgs] Positive ground = more rust?
Hans Duinhoven
h.duinhoven at planet.nl
Fri May 23 13:46:14 MDT 2008
You gain, that the coils of solenoids and relais do not <wear> and will
generate a higher resistence in time.
When this happens, these devices will operate unreliable in time and
faultfinding to such a failure is a nightmare I can tell!
Modern electronic solutions are protected by a constant DC voltage / current
protection.
I have seen such devices connected to f.i. an electronic fuel pump
installation at a car fuel station.
It was called kathode protection.
Cheers,
Hans
----- Original Message -----
From: Paul Hunt
To: Hans Duinhoven ; mgs at autox.team.net
Sent: Thursday, May 22, 2008 5:59 PM
Subject: Re: [Mgs] Positive ground = more rust?
I did 32 years in telecoms and that never came up, although the 'sacrificial
anode' thing did. As I recall all the switching equipment used a +50v supply
and hence a negative ground. I can't see how a length of copper wire would
lose material with the current flowing in one direction but not the other.
Even with contacts one gets a pit and the other a spike, reverse the direction
and the pits and spike change places, but what do you gain?
PaulH.
----- Original Message -----
... I have been tought,
that phone switching equipment like coils and solenoids should be operated
with the ground connected to the positve power.
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