CEBORA S.p.A. 6
3.302.002 03/08/00
The fixed fitting of the torch (50) is a multiple connector with a built-in power start for the
torch electrode, two contacts for the torch gas nozzle, two contacts for the start button, four
contacts to recognize the type of torch, and a pneumatic actuator for the plasma gas. The torch is
connected to this fitting; depending on the model, it may use all or only part of these contacts
and actuators.
A second reed is positioned to detect the presence of the fitting safety hood (50), to prevent
the power source from operating without the hood.
The connector (P) on the rear panel (see fig. 3.2.1) is set up to connect to the cooling unit art.
1339.
On the rear panel is mounted the pressure regulator (35) complete with filter, pressure gauge
and pneumatic fitting to connect the plasma gas. The regulator makes it possible to adapt the gas
pressure to the type of torch being used.
The fuse board (8) contains the fuses for the following circuits:
− Electronic boards power supply;
− Pre-charging of the DC capacitor (40);
− Alternating current devices (solenoid valves (29) and remote switches (5) and (18).
The pre-charge board (7), controlled by the Control board (62), performs:
– Pre-charges the DC capacitor (40), and sends the information regarding the voltage
reached by the capacitor during this phase to the control board;
– Pre-magnetizes the power transformer (79);
– Supplies power to the socket (21) for the cooling unit.
Based on the signals to its inputs, the control board (62) prepares the power source to run by
controlling the service devices (solenoid valves (29) and remote switches (5) and (18), processes
the reference signal of the cutting current to send to the driver board (9), and makes sure that
proper operating conditions are always present.
These functions are governed by the control board microprocessor (62), which also manages
all of the information displayed by the operator panel (64), including the system diagnostics
messages.
The operator panel (64) includes:
− Two displays to show error codes, the cutting current and nozzle hole diameter;
− A set of LEDs to indicate the operating status;
− A potentiometer to adjust the cutting current.
For more detailed information, see the Instruction Manual.
The driver board (9) forms the actual system regulator. It generates the IGBT pilot signal,
calculating the waveform (duty cycle) by comparing the current reference signal from the control
board (62) to the current reaction signal from the transducer (71).
The HF board (15), combined with the HF transformer (69), generates the high voltage and
high frequency pulses needed to start the pilot arc. Its operation is conditioned by the value of
the power source output voltage, measured between the positive output pole of the power source
and the terminal downstream from the choke (43). With a voltage greater than 200 VDC, the
circuit generates the high voltage and frequency pulses; at lower voltages the circuit stops.
This system takes relies on the principle according to which the output voltage is greatest,
approximately 260 VDC, under no-load, while with the pilot arc or transfer arc this voltage is
determined by the cutting conditions (level of current, material to be cut, type of gas, etc.), thus
significantly below 200 VDC.
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