[Amps] Re Direct rectification of AC mains to derive the amp, VDD, supply

[peter chadwick]

It depends how the earthing is done. The neutral is earthed at the transformer and several places along its route. If  you earth the neutral when it enters the property, a ruptured neutral then means that the load of the property flows through the earth lead, and depending on where or if the RCD (GFI in US) is wired, it may trip - or may not. If the load is large, that can be a problem. The real nasty is that if the earth pins in the house are connected to the neutral at the entry to the property, and the case of the transceiver is connected to good external earth, a ruptured neutral external to the property means that the path to earth is down the power cable of transceiver. That current can, in some circumstances be the current for several properties and  be far in excess of the transceiver power cable rating.

Depends on how the mains supply is configured: it differs from country to country, and there are generally several different systems depending on what the application is - for example, milking parlours for cows are especially sensitive.

The 240 volt EU supply is a very different animal to the US 120-0-120.


73

Peter G3RZP

========================================
 Message Received: Sep 19 2013, 09:47 AM
 From: "Peter Voelpel" <dj7ww at t-online.de>
 To: amps at contesting.com
 Cc: 
 Subject: Re: [Amps] Re Direct rectification of AC mains to derive the amp,	VDD, supply
 
 With the neutral lost on a direct fed power supply nothing will happen as
 long the neutral connection of the p/s is connected to ground locally.
 At least not in Germany where is not possible to get 115V out of the grid.
 
 I used many transformer less amps in the past without any problem.
 The power supplies built were single phase as well as three phase up to
 10KVA.
 
 73
 Peter
 
 -----Original Message-----
 From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of peter chadwick
 Sent: Donnerstag, 19. September 2013 09:28
 To: Mark Bitterlich; Manfred Mornhinweg; amps at contesting.com
 Subject: Re: [Amps] Re Direct rectification of AC mains to derive the
 amp,VDD, supply
 
 
 >So if I built my next amplifier that is directly rectified by the mains, it
 
  will cause a train wreck?<
 
 If you ground the neutral to an external ground and get a ruptured neutral
 on your feed, who knows? We nearly had a small shopping mall catch fire when
 the 3 phase feed lost its neutral because of a backhoe driver 'skinning' the
 aluminium sheath (which was the neutral) on the feed cable!
 
 73
 
 Peter G3RZP
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