System Description; Introduction; Technical Specifications; Power Source Art. 956 - Cebora PLASMA PROF 123 ACC Service Manual

CEBORA S.p.A.

2 - SYSTEM DESCRIPTION.

2.1 - Introduction.

The PLASMA PROF 123 ACC is a cutting system, designed for plasma arc cutting of electro-
conducting materials. It consists of an electronic Power Source art. 956 and a set of torches and
accessories, to be used in manual applications (see list in the Sales Catalogue).
The Power Source is controlled by microprocessor-based circuits, which manage the
operative functions of the cutting system and the operator interface.

2.2 - Technical specifications.

To check the technical specifications, see the plates affixed to the equipment, the Instruction
Manual and the Sales Catalogue.

2.3 - Power Source art. 956.

Art. 956 is a direct voltage, current controlled Power Source consisting in a three phase bridge
rectifier and a igbt DC/DC converter.
With reference to the electrical diagram of par. 5.1, drawing 4.1 and table 4.2, you can
identify the main blocks that make up the Power Source.
The switch (49) works on the service transformer (53) which feeds the electronic boards and
the internal services through the fuse board (53).
The power transformer (37) primary circuit consists of six windings. When switched
appropriately by the voltage changer, these allow the Power Source to operate at 230, 400 or 440
Vac 50/60 Hz. The service transformer (53) voltage changer is set in the vicinity of the main
voltage changer.
The transformer (37) is powered through contactor (2), which is controlled, in closing, by the
control board (47), once the DC-capacitor (20) pre-charge and transformer (37) pre-
magnetization phases are completed.
From one of the windings of the transformer (37) primary circuit, the 230 Vac voltage is
drawn to power the fan (23) for cooling the Power Source power elements. Since this is directly
connected to the transformer (37) primary circuit, the closing of contactor (2) is sufficient to
power the fan (23).
From the secondary circuit of transformer (37) the mains voltage signal is picked-up and
analyzed by the measure board (57). In particular, the presence and the amplitude of the supply
voltage three phases of the Power Source is checked; any incorrect value causes an error signal
which is sent to the control board (47).
The rectifier bridge (34), connected to the transformer (37) secondary circuit, feeds the
capacitor (20) and the power board (56), which contains the igbt module and the two Hall effect
current transducers to draw the Power Source and the pilot arc output currents.
The igbt module contains the switching item, the igbt, and the freewheeling diode connected
in "chopper" layout.
At the negative output (1) of igbt module on the power board (56) the choke (35), to level the
arc current, is connected; then the HF transformer (50) is connected as well at the output for the
electrode potential, on the central adapter (41) for the cutting torch.
The terminal TP1 of the power board (56) corresponds to the positive output (3) of the igbt
module and represents the output of the ground potential ready for workpiece connection.
On this connection, inside the power board (56), the Hall effect current transducer is
connected, which sends to the control board (47) the Power Source output current signal.
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