Re: Using SCR's For Regulating Input Current (fwd)

["High Voltage list" <hvlist@xxxxxxxxxx>]

Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Thu, 03 Feb 2005 22:21:50 -0600
From: Shaun Epp <scepp@xxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Using SCR's For Regulating Input Current (fwd)

The application is called "phase control", and you'll need more that a 
potentiometer to control it.  Look up motor speed controls, lamp dimmers and 
phase control on google, you'll probably find the information you need.  The 
current will be pulses timed with the line frequency to turn on the SCR's a 
number of milliseconds after each zero crossing that way limiting the 
average current and voltage to the load.  Two SCR's would be a switched 
bridge configuration.
Your peak current each time the SCR's fire will be high.

Good luck,  that's alot of power your dealing with

Shaun Epp

----- Original Message ----- 
From: "High Voltage list" <hvlist@xxxxxxxxxx>
To: "hvlist" <hvlist@xxxxxxxxxxxxxxxxx>
Sent: Thursday, February 03, 2005 4:28 PM
Subject: Using SCR's For Regulating Input Current (fwd)


> Original poster: <sroys@xxxxxxxxxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Mon, 31 Jan 2005 10:57:56 -0600
> From: Carl Litton <Carl_Litton@xxxxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: Using SCR's For Regulating Input Current
>
>
> Would someone please explain how the brick-like high current 'power
> module' blocks containing 2 SCR's are used to regulate current?  We are
> interested in pursuing this as an alternative to heavy/bulky variable
> inductors.
>
> We have such a module rated at about 250 Amps continuous and 1200 Volts.
> It has the 3 main terminals: 1 for AC in and 2 (+/-) used to connect the
> SCR's and provide output.  It also has four small terminals, 2 to the
> gates of the SCR's and 2 to the cathodes of the SCR's.
>
> We have been given to understand that such a module may be placed in 1
> leg of the AC input line (along with a potentiometer and such) to
> regulate the input current as a sort of pulse width modulator.  Current
> demand on our input line is about 80-120 Amps and we would like to
> restrict it to a variable 25 to 60 Amps with this type of setup.
>
> We would appreciate a brief description of such a control circuit or a
> link to the explanation and/or a schematic.
>
> Thank you,
>
>
> Carl Litton
>
>
>
>