Sorensen DCS Series 3kW Supplies
Theory of Operation
Local OVP Set Point Control
Potentiometer R29 (or R29A depending on the production part used) is a 20-turn trimpot which
provides a 0-5V reference signal to the OVP circuit on the A2 PCB via pin 17 of connector P1.
Voltage and Current (V & I) Control Setting Check Switch SW3
The momentary switch SW3 allows the front panel voltage and current controls settings to be
previewed on the voltmeter and ammeter displays. When depressed, the switch disconnects the
normal meter inputs from the A2 PCB and connects a calibrated signal from the front panel
controls to the meter inputs. The resistive divider formed by R24, R25, and R26 scales and
calibrates the signal from the voltage control potentiometer R27. Resistors R21-R23 are used to
scale and calibrate the signal from the current limit potentiometer R20.
OVP Set Point Check Switch SW4
Similarly to the V & I CHECK switch, momentary switch SW4 allows the front panel OVP
potentiometer setting to be displayed on the voltmeter. When depressed, the switch disconnects
the normal A2 PCB voltmeter input line and connects a calibrated signal from the OVP
potentiometer to the voltmeter. Resistors R30-R32 are used to scale and calibrate the OVP
control signal.
Remote/Local Switch SW1
This press ON/press OFF switch activates both the voltage and current remote programming
selector circuits on the A2 PCB via P1 connector pin 19. See
for a description of
the programming mode selector circuit.
Output Standby Switch SW2
This press ON/press OFF switch shuts off the power supply output so that load and/or
programming changes can be made without shutting off the AC input to the supply. The switch
activates the A2 PCB internal shutdown circuit through pin 14 of connector P1. See
for a description of the internal shutdown circuit operation.
Indicator LEDs
The indicator LEDs for voltage mode operation, current mode operation, over-temperature
shutdown, remote programming operation, shutdown, and OVP circuit activation are located on
the A1 PCB. See
for a description of how the related circuits operate.
IEEE-488 Option P2 Connector Signals and Indicator LEDs
Connector P2 provides the connection to the optional IEEE-488 digital programming, readback,
and monitoring PCB. Eight LED indicators for
ADDRESSED
,
SERVICE REQUEST
,
SYSTEM FAULT
,
FOLD
,
ERROR
,
FAULT
,
POLARITY
, and
ISOLATION
conditions with their common ground are
connected to pins 1-9. Pin 10 provides the option board with a signal to indicate the status of
the Remote/Local switch SW1 on the front panel. Pin 11 provides a signal to the option board
whenever either the front panel standby switch or the A2 remote shutdown circuit are activated.
Operation Manual
5-15
