Theory of operation – Hypertherm Powermax125 Service Manua User Manual
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Powermax125 Service Manual 808070
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8 – Troubleshooting and System Tests
Theory of operation
480 V and 600 V CSA 3-phase power supply functional description
AC power enters the system through the power switch (S1) to the input diode bridge (D38). The voltage from the bridge
provides a nominal 650 VDC bus voltage for the 480 V power supply and 810 VDC bus voltage for the 600 V power
supply. The bus supplies voltage and current to the inverter and the flyback circuit (DC to DC converter) on the power
board (PCB3). The power board provides noise suppression and spike protection. A “soft start” is implemented by the
power board resistors (RT4, RT5) and relays (K2, K3).
The inverter consists of a dual IGBT (insulated gate bipolar transistor) package (Q12), the power transformer, an output
current sensor, and the control circuit. The inverter operates as a pulse-width modulated half-bridge circuit driving an
isolation transformer. The output of the isolation transformer is rectified by the output bridge (D36 and D37).
The output circuitry consists of 2 current sensors located on the power board, the pilot arc IGBT (Q13), and the output
choke.
The digital signal processor (PCB2) monitors and regulates the system’s operation and safety circuits. The amperage
adjustment knob on the control board (PCB1) sets the output current to the desired value: 30 – 125 A. The system
compares this set-point to the output current by monitoring the current sensors and adjusting the output of the inverter
IGBT module (Q12).
400 V CE, 380 V CCC 3-phase power supply functional description
AC power enters the system through the power switch (S1) to the input diode bridge (D38). The voltage from the bridge
provides a nominal 510 to 540 VDC bus voltage. The bus supplies voltage and current to the inverter and the flyback
circuit (DC to DC converter) on the power board (PCB3). The power board provides noise suppression and spike
protection. A “soft start” is implemented by the power board resistors (RT4, RT5) and relay (K2).
The inverter consists of a dual IGBT package (Q12), the power transformer, a current sensor, and the control circuit. The
inverter operates as a pulse-width modulated half-bridge circuit driving an isolation transformer. The output of the
isolation transformer is rectified by the output bridge (D36 and D37).
The output circuitry consists of 2 current sensors located on the power board, the pilot arc IGBT (Q13), and the output
choke.
The digital signal processor (PCB2) monitors and regulates the system’s operation and safety circuits. The amperage
adjustment knob on the control board (PCB1) sets the output current to the desired value: 30 – 125 A. The system
compares this set-point to the output current by monitoring the current sensors and adjusting the output of the inverter
IGBT module (Q12).