Bias/Manual Control; Summing Amplified Circuit - Ametek DPA1 Series Installation, Operation And Troubleshooting Instructions

Theory of Operation
4-30.

BIAS/MANUAL CONTROL

4-31. The BIAS/MANUAL control is a potentiometer. A regulated +12 V dc from the Power Supply circuit is
supplied to one end of the potentiometer and a regulated –12 V dc is supplied to the other end. The control
provides an adjustable bias/manual signal to the summing point feeding the Summing Amplifier circuit. The
bias/manual signal may be positive, negative, or zero.
4-32.

SUMMING AMPLIFIED CIRCUIT.

The Summing Amplifier (AMP-1) circuit amplifies the resultant value of the signals applied to the summing
point (pin 4, the inverting input on AMP-1). The control signal from the process controller is applied across
resistor R1 and is applied to the summing point through the GAIN control. At the summing point, the control
signal is algebraically summed with the Voltage feedback signal through resistor R4, the bias/manual signal
through resistor R3, and the compensation signal form the output of AMP-1 through resistor R6 and capacitor
C1. When the optional Current Limit is used, its output is also summed with other signals at the summing
point. The control signal from the process controller is negative, and the feedback signals are positive. The
bias/manual signal may be positive, negative, or zero.
26 AMETEK HDR Power Systems
Phase/AMP Series DPA1/DCPA1
Document 9100030