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machine, the highest voltage, with which it is possible to come into
contact, is the open-circuit voltage between the clamps.
•
The maximum open-circuit voltage of the plasma machines is
established by national and international standards (EN 60974-1)
depending on the type of current to be used, on its waveform and on the
hazards arising from the work place. These values are not applicable to
the strike currents and those for stabilisation of the arc that could be
above it.
•
The open-circuit voltage, for as many adjustments as possible, must
never exceed the values relating to the various cases shown in the
following table:
Case Working conditions
Open-circuit voltage
1
Places with increased
risk of electric shock
DC current: 113V
peak value
AC current: 68V
peak value and 48V
effective
2
Places without increased
risk of electric shock
DC current: 113V
peak value
AC current: 113V
peak value and 80V
effective
3
Torches held
mechanically with
increased protection for
the operator
DC current: 141V
peak value
AC current: 141V
peak value and
100V effective
4
Plasma cutting
DC current: 500V
peak value
•
In case 1, the dc machines with rectifier must be built in such a way that,
in case of a fault developing in the rectifier (for example open circuit,
short circuit or lack of power), the permitted values cannot be exceeded.
The welding machines of this type can be marked with the symbol:
S
•
Before opening the machine switch off the machine and disconnect it
from the power socket.
•
Only personnel authorised by this company can carry out maintenance
on the machine.
2.1 ELECTROMAGNETIC COMPATIBILITY (EMC)
This machine conforms to EN 60974-10 standard. However, the
electromagnetic emissions generated could prove not be compatible with
the maximum permitted levels for some classes of electrical equipment, such
as the following:
•
Domestic electronic appliances (radios, TVs, videos, telephones,
burglar alarms, etc.).
