Control Board (48) 5602551 - Cebora 337 Manual De Servicio

CEBORA S.p.A.
When the welding torch with an active pilot arc is placed near the workpiece to be
cut, sensor SA2 detects the passage of current on the power source ground conductor.
This signal is sent to the control board through connector J4.
In turn, the control board sends a signal to connector J4 of the diodes board (32)
and, by means of opto IC1, mode commutation from pilot arc to transferred arc is
commanded, thus disabling IGBT Q1 (40).
The output signal of current sensor SA1 is sent to the control board (48) through
connector J4 to read and check the cutting current.
Using a resistive divider, the machine output voltage is taken from the diodes board
(32) and sent to the control board (48) by means of connector J4.

2.8 control board (48) 5602551

The control board (48) oversees all power source functions and is managed by two
microcontrollers.
The main microcontroller manages inverter, LCD display, diagnostics, and torch
recognition; it measures the temperature of the IGBT dissipater and the diodes
dissipater; it measures the pressure of air circuit and of other components such as
cooling fans and solenoid valves.
The secondary microcontroller oversees the inverter safety device.
The power converter uses the full bridge configuration consisting of four switches
made using two IGBT power modules. Each module contains two IGBTs and two
recirculation diodes. The full bridge IGBTs are controlled in isolated mode by two pulse
transformers contained in the control board (48).
Fixed to the aluminium heatsink dissipater (42) is the temperature sensor (NTC
resistor) which measures the temperature of inverter IGBTs. The sensor is connected to
connector J3 of control board (48).
Fixed to the aluminium heatsink dissipater (39) is the temperature sensor (NTC
resistor) which measures the temperature of output rectifier diodes. The sensor is
connected to connector J5 of control board (48).
Cooling fans can run at two speeds: full or reduced. Depending on the measured
temperature, the main microcontroller commands fan speed reduction by varying the
supply voltage. The change in fan speed is obtained by using the voltage regulator that
powers them, located on the services board (6).
The fan management logic is a follows:
1. At machine start-up, fans run for 3 minutes at maximum speed;
2. After 3 minutes, if the temperature measured by at least one thermal probe -
(29) or (38) - exceeds 59°C, fans continue to run at maximum speed.
3. When both thermal probes - (29) or (38) - measure a temperature lower than
59°C, the fan speed will be reduced.
4. When both thermal probes - (29) or (38) - measure a temperature lower than
39°C, fans will stop.
5. At machine start and during machine operation the fans will run at maximum
speed. When the work process is completed, fans go back to being managed
according to previous points 3 and 4.
The air unit (16) features a pressure sensor whose output signal is sent to the control
board (40) by means of connector J1.
The output signal connections to the central adapter of welding torch (61) are
brought to connector J6 of control board (48); using these signals the control board
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20/12/2019