CEBORA S.p.A. 5
event the torch is without nozzle or with pilot arc conductor interrupted, and the operator tries to
light the pilot arc.
Once contactors TLP (32) and TLM (32) are opened, solenoid valve EL1 (7) remains opened
for the post-gas time (60 sec. not adjustable).
When the torch approaches the work piece, with the pilot arc on, the arc current begins to
circulate in the work piece, as this is the preferred path due to the voltage drop on resistor (36).
During cutting and pilot arc conditions, control board (4) detects the arc voltage to verify
eventual power source output short-circuit. A voltage lower than 40 Vdc is considered not
corrected to keep the arc light on, and so produces the power source block, with contactors TLP
(32) and TLM (32) opened, and lamp G (39) flashing, indicating the block cause code (1 flash
with 1 sec. pause).
When cutting ends the contactors TLP (32) and TLM (32) are deactivated, and solenoid valve
EL1 (7) remains opened for the post-gas time to complete the torch cooling. Once this time has
elapsed, the solenoid valves EL1 (7) is deactivated, and the power source returns to its initial
resting state (power circuit not powered and no output voltage).
The fan (34) is supplied, through control board (4), at the same power source supply voltage,
without any control from control board (4).
The pressure switch (8) inserted in the plasma gas line sends to the control board (4) the
insufficient gas pressure signal, when the pressure is lower than 3,2 bar (minimum working
pressure). Its normally closed contact also commands the lamp L (39) to signal the gas pressure
error (lamp lit = pressure low).
The thermostat in reality is made by two thermostatic switches connected in series between
them, located on two columns of the transformer (38) (temperature correct = contacts closed).
The intervention of one of the two thermostats is sufficient to produce the power source
block, signaled by lamp G (39).
The signals processed by the electronic boards and present at their connectors are listed in the
tables in chapter five of this manual.
3.302.170 06/07/04
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