Cebora PLASMA SOUND PC 70/T Manual De Servicio página 39

CEBORA S.p.A.
The two central sockets of the two windings, terminals 2 and 5, are connected to the
screw terminal of secondary winding board (32) identified as S2-S5.
Terminals 1 and 6 are connected to the anodes of the rectifier diodes in the ISOTOP
D10 module. Terminals 3 and 4 are connected to the anode of rectifier diodes in the
ISOTOP D6 module. The rectifier diodes in the ISOTOP modules are used to rectify the
alternating current generated by the inverter. Inductor (53) for levelling the power
source output current is connected between the + output of the diodes (terminal L1 of
secondary winding board (32)) and the + terminal of secondary winding board (32)
(terminal L2).
Each ISOTOP diode module contains two diodes. These two diodes are connected
in parallel to one another outside the module.
A direct output voltage to be sent to the power source is available at the (+) and (-)
terminals on secondary winding board (32).
The cutting current is adjusted by an inverter made up of IGBT board (31) and IGBT
boards (30), which are controlled as appropriate by control board (48) and display
board (57).
The heatsinks and magnetic circuit are cooled by fan (28) supplied directly at 24V
through power source (6) connected to service filter board (7).
The power source power outputs, to which the welding torch is connected, are
contained within the central adapter on the front panel. This multiple connector
incorporates a power socket for the welding torch electrode, two contacts for the
welding torch nozzle, two contacts for the start pushbutton and four contacts for torch
type recognition and an air fitting for the plasma gas. This centralised attachment is
equipped with a protective sleeve. A reed switch connected to connector J9 of display
board (57) detects the presence of the protective sleeve and prevents the power
source from operating if it is not present.
Service filter board (7) 5602595
The three mains phases leading from switch (10) are carried to points U2, V2 and
W2 of service board (6).
The board detects the zero crossing sequence of the three phase-to-phase voltages
through optocouplers IC1, IC2 and IC3. The output signals to the optocouplers are
sent to microcontroller IC4 which in turn sends an enabling signal to control board (48).
If the zero crossing sequence is not correct, the control board (48) disables the inverter
and sends error message ERR 67 to the LCD display.
An incorrect zero crossing sequence of the phase-to-phase voltage can occur when
a mains phase is missing or, for example, when the mains neutral is accidentally
connected instead of a mains phase. A capacity drop in capacitors C17, C18 and C19
could determine an incorrect phase sequence.
The two phases leading from input points V2 and W2 are carried to the TF1 service
transformer primary winding connections.
Service transformer TF1 contains a primary winding fitted with sockets that allow it
to adapt to 208, 230, 400 and 440 V mains voltages.
At machine power-on, the two phases are applied between points 0 V and 440 V of
service transformer TF1 because the control has not yet determined the mains voltage
level. A rectified, smoothed, non-stabilized DC voltage obtained from the secondary
winding of service transformer TF1 is supplied from pin 1 of connector CN1 to pin 1 of
connector CN9 of control board (48). This voltage is directly proportional to the mains
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10/07/2019