I'll tell you!
Back in the nineties at Tadiran we designed for the Navy a switching power
supply based on a PFC IC the rationale was that in order to correct the power
factor, it had first to make it sinusoidal, so as to resemble the voltage
waveform. In this format, the input is inductive, not capacitive and the damned
thing was so quiet that we had trouble convincing the inspector that the supply
was working. The Navy had very stringent requirements on second harmonic
generation of the mains (120 Hz), because it interferes with sonar operation.
Alex 4Z5KS
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of peter Chadwick
Alex 4Z5KS
Sent: Friday, September 27, 2013 11:36 PM
To: Bill Turner; Amps
Subject: Re: [Amps] Direct rectification of AC mains to drive the amp,
Bill,
As I understand it - and quite likely I' m wrong - with a normal rectifier and
input C, the rectifiers draw current only when the transformer volts exceed the
reservoir capacitor volts. This puts a large harmonic component on the input
which isn't in phase. Using a switching 'boost inverter' allows the supply
current to effectively see a resistive load.
I know the people at Alpha were telling me that meeting EU requirements was
difficult with a usual transformer/ rectifier/capacitor supply, but I don't
know how they got over that.
With some years of professional experience regarding EU requirements and their
development, I personally feel that the Commission people have all demonstrated
that they are a useless load of idiotic incompetents, busily trying to
legislate things they do not understand.......
thank heavens I've retired.....
========================================
Message Received: Sep 27 2013, 05:04 PM
From: "Bill Turner" <dezrat1242@yahoo.com>
To: "Amps" <amps@contesting.com>
Cc:
Subject: Re: [Amps] Direct rectification of AC mains to drive the amp,
ORIGINAL MESSAGE: (may be snipped)
On Wed, 25 Sep 2013 10:10:06 +0930, you wrote:
>
>Yes all that you mention below is correct Jim. That's why I commented in an
>>earlier post that an individual QRO amp builder would get away with doing
>>this questionable 3 kW power supply realization technique, but no commercial
> >SS amp manufacture would be able to do this due to the electrical codes in
>>respect of EU power factor rules and product compliance certification.
REPLY:
Power factor correction is an area I am a bit hazy on. Could someone explain
why the power factor would be different between a direct-rectified PS and a
transformer-isolated one? Either one charges the capacitors with a series of
pulses. What's the difference in power factor?
73, Bill W6WRT
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