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Phase/AMP Series DPA1/DCPA1
4-5.
Thus far, only the Power SCR circuits of the DPA-1 PHASE/AMP have been discussed. The
PHASE/AMP also contains Power Supply, Summing Amplifier, Soft Start, Soft Start Reset, SCR Firing, Pulse
Shaper, Voltage Feedback, Current Limit, and Bias/Manual circuits. A simplified block diagram showing the
functional relationship of these circuits is shown in Figure 4-5. A functional description of each of the blocks in
the diagram is provided in paragraphs 4-6 through 4-23.
4-6.
POWER SUPPLY CIRCUIT.
4-7.
The function of the Power Supply circuitry is to supply the proper regulated DC and pulsating DC
Voltages to the various circuits in the DPA-1 PHASE/AMP. Voltage outputs are supplied to the
Summing Amplifier, BIAS/MANUAL control, Soft Start Reset, and SCR Firing circuits.
Figure 4-5 Simplified Functional Block Diagram of DPA-1 PHASE/AMP
4-8.
SUMMING AMPLIFIER CIRCUIT.
4-9.
Inputs are supplied to the Summing Amplifier circuit from the Power Supply circuitry and the summing
point. The amplifier is powered by the regulated +12 V dc and the regulated –12 V dc supplied by the Power
Supply. The function of the amplified is to amplify the resultant value of the signals applied to the summing
point by the process controller, BIAS/MANUAL control, Voltage Feedback circuit, and optional Current Limit
circuit when used. The amplifier produces a resultant DC output signal which is proportional to the algebraic
sum of the signals applied to the summing point. The output of the Summing Amplifier circuit is applied to the
Soft Start Circuit.
4-10.
SOFT START CIRCUIT.
4-11.
Inputs are supplied to the Soft Start circuit from the Summing Amplifier circuit and the Soft Start Reset
circuit. The function of the circuit is to allow the power delivered to the load from the PHASE/AMP to be
brought up slowly when the unit is turned on. This feature prevents the possible clearing of fuses when the
unit is turned on. The output of the Soft Start circuit is supplied to the SCR Firing circuit.
Document 9100030
AMETEK HDR Power Systems
Theory of Operation
23
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