Snap-On TIG 250 AC-DC, Руководство по обслуживанию

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CEBORA S.p.A.
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3.4 - Alarm signals.
3.4.1 - Led (Y) off. Power source output voltage greater than 48 Vac.
Alarm active only in AC operation.
For safety reasons the power source is blocked if the voltage at its output exceeds 48 Vac, in
AC operation.
In open circuit AC operation, the power source has an output voltage of approximately 28
Vdc, since only SCR1 is controlled, while SCR2 is controlled only when the welding current is
already present at the power source output.
Control of hazardous AC voltage at the power source output is activated to make sure that any
breakdown in the control circuits or short-circuited thyristor generates alternating voltage with
the open circuit power source.
To analyze the problem, see “open circuit operation” par. 3.3.7, “loaded operation” par. 3.3.8
and “AC operation” par. 3.3.9.
3.4.2 - Led (F) on. Temperature of the transformer (46) or inductor (50) too high, or low
pressure of the coolant fluid.
With this alarm the power source does not deliver current but the fan (45) continues operating
for rapid cooling. Normal operation is automatically restored when the temperature returns
within the allowed limits.
If the alarm is due to the pressure of the coolant fluid, check operation of the cooling unit (see
Cooling Unit Service Manual).
To identify the origin of the blockage, it is possible to cut out the cooling unit by connecting
together terminals 1 and 3 of the connector (13) on the rear panel of the power source, or insert
the special connector provided with the power source.
In case of overtemperature:
−
Make sure the fan (45) is working properly (see par. 3.3.2).
−
Check for proper air flow, and make sure there is no dust or blockage to cooling of the
internal components.
−
Make sure that operating conditions meet specifications; in particular, observe the “duty
cycle”.
−
Check the wiring connections between terminals 3 and 4 of J8 on control board (40)
thermostat in the transformer (46), thermostat in the inductor (50) and connector (13) on the
rear panel of the power source.
−
Make sure voltage = 0 Vac (short-circuit) on J8 of control board (40), terminals 3 and 4. If
incorrect, with the power source off temporarily disconnect the thermostats and the connector
(13) and check the resistance of each: at ambient temperature the thermostat contacts must be
closed, and with the appropriate fluid pressure the pressure switch contact must also be
closed. If incorrect replace control board (40).
3.302.221 15/01/07