GPD-X303S Series User Manual 
Principle of Operation 
 
Overview 
The power supply consists of the following. 
•  AC input circuit 
•  Transformer 
•  Bias power  supply including rectifier, filter, 
pre-regulator and reference voltage source 
•  Main regulator circuit including the main 
rectifier and filter, series regulator, current 
comparator, voltage comparator, reference 
voltage amplifier, remote device and relay 
control circuit 
The block diagram below shows the circuit 
arrangement. The single phase input power is 
connected to the transformer through the input 
circuit. Details of each part are described in the 
next page. 
Block diagram 
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