Ametek Sorensen DCS-E Series, Руководство по эксплуатации

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Theory of Operation Sorensen DCS Series 1kW and 1.2kW Supplies
3-8 M362500-01 Rev K
During remote voltage programming of the OVP trip level the internal 1mA current source is
disconnected by removing the jumper that connects pin 3 and 16 of J3. The reference voltage at
pin 6 of U3-2 is then provided directly by the external voltage source. Switch SW1-4 is used to
select the programming range; 0-5V (with the switch closed) or 0-10V (with the switch open) by
utilizing R1 as a voltage divider. For current programming the internal 1mA current source is
replaced with a 0-1mA external source to provide the required 0-5V reference signal. For
resistive programming switch SW1-8 is opened to disconnect the front panel adjusting
potentiometer and the internal 1mA current source is connected to the external 0-5k ohm
potentiometer to provide a 0-5V reference.
O
VER
T
EMPERATURE
C
IRCUIT
U8-3 and associated circuitry consisting of R57-59 and thermister RT1 provide overtemperature
protection by monitoring the main FET heatsink temperature. When negative temperature
coefficient device RT1 is heated, the value of resistance decreases until the voltage on U8 pin 9
equals the voltage on U8 pin 10 at which time U8 pin 8 will provide a high signal to the U6 PWM
shutdown input through CR27.
R
EMOTE
ON/OFF C
IRCUIT
A TTL high signal applied between pins 14 (positive) and 2 (negative) of connector J3 activates
optocoupler U1 which turns on transistor switch Q3 by pulling its base low. This applies 12V
through diode CR11 to the shutdown pin of the PWM thereby shutting down the power supply
output. A 12-250Vac or 12-130Vdc signal applied between pins 1 (positive) and 2 (negative) of
connector J3 will also activate U1 and disable the power supply output. Diode CR14 rectifies ac
inputs while resistors R37 and R38 limit the current through the optocoupler. Diode CR13
provides protection against reverse polarity signals.
R
EMOTE
P
ROGRAMMING OF THE
O
UTPUT
V
OLTAGE
During remote programming of the output voltage with an external voltage source (0-5V or
0-10V) the local operation jumpers connecting J3 pins 8 to 9 and 20 to 21 are removed and the
external source is connected between pins 9 (positive) and 12 (negative) of connector J3. The
input signal at J3 pin 9 is clamped by CR7 and CR8 and filtered by R409 and C104 to protect
the input buffer amplifier U14-2 which provides the 0-5V programming signal for the output
voltage. When using a 0-10V programming source, switch SW1-3 is closed to provide the
necessary voltage divider to scale the reference voltage back to 0-5V.
For remote programming with an external 5k resistance the jumpers connecting J3 pins 8 to 9
and 20 to 21 are removed, pins 9 and 21 are connected to the counterclockwise end of the
external 5k ohm potentiometer and the tap and clockwise end are connected to pin 12. The
internal 1mA current source at pin 21 develops a 0-5V potential across the potentiometer,
depending on the potentiometer setting, which is fed to pin 2 of U5 through buffer amp U14-2.
During remote programming of the output voltage with an external 0-1mA current source, the
jumper connecting J3 pins 20 and 21 is removed, the front panel voltage control is set fully
clockwise and the external current source is connected between pins 8 (positive) and 12
(return). Varying the current source from 0-1mA causes 0-5V to be developed at the reference
pin of the voltage control circuit.