User Manual

Unit 6 – +32V power supply
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4. Temperature control:
4.1. Function:
Its function is to protect against the power supply temperature increasing.
4.2. Technical Description:
Through a NTC (VR1) thermistor that is set up over the SCR’s heat sink of the three-phase
rectifier bridge, a sample voltage is compared to a reference voltage that is obtained by R4 and trimpot
R1. If the power temperature overcome the value determined trimpot R1, the integrated circuit IC1
output passes to the high level by resistor R5 and diode D1and acts in the control pins from the phase
controller circuits from the three-phase control power board (FTE012), decreasing the SCR’s conducting
angle and consequently reducing the output voltage.
4.3. Circuit Diagram CTT002: