AMETEK DCS-E 1KW Series - Manual (Page 55)

Sorensen DCS Series 1kW and 1.2kW Supplies Theory of Operation
M362500-01 Rev H 3-9
The front panel remote programming indicator is controlled by op amp U8-4. Resistors R55
and R56 form a voltage divider with the 6.2V reference which develops a nominal 0.3V at pin 12
(the non-inverting input) of the op amp. During local operation, current flow through diode
CR15 and the front panel voltage control provides a higher voltage at pin 13 (the inverting input)
keeping U8-4 output low. During remote programming there is no current flow through diode
CR15 and the output of U8-4 goes high illuminating the remote programming indicator through
diode CR4, resistor R13 and pin 13 of connector J1. The high signal is also provided at pin 4 of
connector J3 for remote monitoring purposes.
R EMOTE P ROGRAMMING OF THE O UTPUT C URRENT L IMIT
During remote programming of the output current limit with an external voltage source the local
operation jumpers connecting J3 pins 10 to 11 and 22 to 23 are removed and the external
source (0-5V or 0-10V) is connected between pins 10 (positive) and 12 (negative). The input
signal at J3 pin 10 is clamped by CR5 and CR6 and filtered by R411 and C103 to protect the
input buffer amplifier U14-1 which provides a 0-5V programming signal for the output current.
This signal is further reduced to a 0-2V signal with a voltage divider consisting of R20 and
R146. When using a 0-10V programming source, switch SW1-1 is closed to provide the
necessary voltage divider to scale the reference voltage back to appropriate 0-5V level.
For remote programming with an external 5k resistance the jumpers connecting J3 pins 10 to
11 and 22 to 23 are removed, pins 10 and 22 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 22 develops a 0-5V potential across the potentiometer,
depending on the potentiometer setting, which is fed to pin 3 of U4-1.
During remote programming of the output current with an external 0-1mA current source, the
jumper connecting J3 pins 22 and 23 is removed, the front panel voltage control is set fully
clockwise and the external current source is connected between pins 11 (positive) and 12
(return). Varying the current source from 0-1mA causes 0-5V to be developed at the reference
pin of the current control circuit.
The front panel remote programming indicator is controlled by op amp U8-1. Resistors R55
and R56 form a voltage divider with the 6.2V reference which develops a nominal 0.3V at pin 3
(the non-inverting input) of the op amp. During local operation, current flow through diode
CR16 and the front panel voltage control provides a higher voltage at pin 2 (the inverting input)
keeping U8-1 output low. During remote programming there is no current flow through diode
CR16 and the output of U8-1 goes high illuminating the remote programming indicator through
diode CR2, resistor R13 and pin 13 of connector J1. The high signal is also provided at pin 4 of
connector J3 for remote monitoring purposes.
3.2 Meter Circuit (A1 Assembly)
The A1 assembly is comprised of the voltmeter and ammeter displays, the output voltage and
current limit controls, the local operation OVP adjusting potentiometer and the indicator LEDs.
The operation of the voltage and current controls, the OVP potentiometer and the indicator
LEDs is covered in the A2 description in Section 3.1. Refer to the schematic diagram in Section
6 for the following discussion.