Igbt Board (31) 5602556; Diodes Board (32) 5602553 - Cebora 337 Manual De Servicio

CEBORA S.p.A.
After the control board (48) has determined the value of the mains voltage, the
control board (48) sends to the services board connector J5 the commands for
commutating relays K1 and K2 on the services board (6). Relays K1 and K2 are
commanded to optimally adapt the primary coil of the service transformer (5) to the
mains voltage value present at the machine inlet. From connector J5 the control board
(48) sends the commands to relays RL1 and RL2 located on the IGBT board (31) for the
correct commutation of the primary coils of the power transformer (52) depending on
the mains voltage value present at the machine inlet.
The services board (6) is equipped with a voltage regulator for stabilising the voltage
applied to the two DC fans used to cool semiconductors and magnets. The control
board (48) can, using optoisolator U10, reduce the voltage of the voltage regulator that
powers the fans to reduce their speed. The control board (48) can, using optoisolator
U9, enable or disable the voltage regulator that powers fans.
Connectors F4 and F5 of the services board (6) receive the START signal coming
from the manual welding torch through the central adapter. The signal is isolated from
the machine output potential by relay RL6.
The continuous solenoid valve that manages air is controlled by the services board
(6) through connector J9.

2.6 IGBT board (31) 5602556

The primary coils of the power transformer (52) are commutated by relays RL1 and
RL2 present on the IGBT board (31). Coils RL1 and RL2 are commanded by the
services board (6) depending on the value of the mains voltage. When the mains
voltage is 220 VAC, the two primary coils are parallel connected (RL1 = energised, RL2
= de-energised). When the mains voltage is 400 VAC, the two primary coils are series
connected (RL1 = de-energised, RL2 = de-energised).
The resistor (45) connected to connector CN1 of the IGBT board (31) together with
the two electrolytic capacitors, also present on the board, create an RC network
(snubber) used to reduce possible voltage oscillations on both ends of the direct
voltage. Said oscillations are linked to the power converter IGBTs commutation and to
the mains line inductance.
In the IGBT board (31) there is amperometric transformer SH1 used to read the
current circulating in the power transformer primary coil (52). The signal exiting SH1 is
used by the control board (48) to regulate both pilot arc and cutting current.

2.7 Diodes board (32) 5602553

The diodes board (32) features two Hall-effect current sensors labelled SA1 and
SA2. Sensor SA1 is for measuring the cutting current on the power source ground
conductor, whereas sensor SA2 is for measuring the transfer arc. Connected under the
diodes board (32) and fixed to the dissipater (39) is IGBT Q1 (40). When activated, the
purpose of Q1 is to allow current to circulate through the nozzle at the start of the
cutting process.
When IGBT Q1 is activated, terminal M1 will have the same voltage that is present
on terminal J3, i.e. the positive voltage exiting the inverter after the output choke.
3302336-B
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20/12/2019