Cebora SYNSTAR 270 T Manual De Reparaciones página 28

Refer to the "wiring diagram and parts list annex" provided with the machine, to identify the main blocks that make
up the power source.
Main switch (14) powers power board (56), which contains all the power source power elements.
More specifically, in the power board (56) it is possible to identify (fig. 2.3.1):
− mains voltage filter for reducing reflected conductive interference on the mains network;
− input bridge rectifier, which converts the mains voltage into direct current voltage for inverter operation;
− the IGBT inverter, which generates square wave alternating voltage for power transformer T4, also fitted to power
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board (56);
− AT, T3, for detecting the current flowing towards the primary winding of power transformer T4;
− bridge rectifier for the current flowing in the secondary winding of power transformer T4;
A board with the inverter control circuits is fitted in non-removable manner to power board (56) (this is referred to
below as the INV board).
Given the particular type of installation, i.e. welded directly to the J7-8-9 connector of power board (56), the INV board
is considered an integral part of power board (56).
The INV board contains a microprocessor which manages the operation of the inverter independently.
It receives information on mains voltage status via optocoupler OP1 on power board (56), the primary and secondary
current reaction signals, the power source output voltage signal and temperature signals from the NTC sensors on
power board (56).
It communicates with panel board (47), which acts as the main power source control via a CAN-BUS line: it receives start
and reference commands for inverter management and sends information on the operating status of the inverter.
The mains voltage present at the input of the incoming bridge rectifier is also sent to the primary winding of service
transformer (54), which is responsible for supplying voltages to all welding system circuits.
The secondary voltages of the service transformer are:
− see Fig. 2.3.1 and connectors map, Section 5.7:
− 30 VAC for the power supply to power source control circuits;
− 27 VAC for the power supply of SRS module (15)
− 18 VAC for the isolated supply to interface circuits with the cooling unit (optional);
− 220 VAC, supplied by an intermediate socket of the primary winding of service transformer (54), for supplying the
cooling unit, through socket (15) on the power source rear panel.
The inverter consists of four IGBTs connected in H-bridge configuration, driven by driver circuits near the IGBT modules,
controlled in turn by the INV board.
The purpose of the inverter is to generate a square wave alternating voltage for power transformer T4.
The welding current is adjusted by modulating this voltage accordingly.
The AT, T3, fitted to the primary winding circuit of power transformer T4, provides the current reaction signal used to
verify that the inverter is operating correctly. This signal does not normally influence welding current regulation.
Power transformer T4 provides the secondary winding with appropriate welding voltage and current values.
Its power secondary consists of 2 windings connected to a common point on inductor terminal L3, necessary for
welding current levelling.
The other ends of the secondary windings are connected to secondary diode assembly on power board (56), which
rectifies the alternating current generated by the inverter making it available at the power source output.
The secondary diode assembly is made up of 10 diodes connected to a common cathode. The output voltage is
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Fig. 2.3.1 (Item no 564)
NOTE
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