Service Manual
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ELECTROMAGNETIC COMPATIBILITY
EMC INTRODUCTION
The 400V CE power supply has been built
in compliance with standard EN50199. To
ensure that the equipment works in a
compatible manner with other radio and
electronic systems, the equipment should
be installed and used in accordance with
the information below to achieve
electromagnetic compatibility.
The limits required by EN50199 may not
be adequate to completely eliminate
interference when the affected equipment
is in close proximity or has a high degree
of sensitivity. In such cases it may be
necessary to use other measures to
further reduce interference.
This plasma equipment should be used
only in an industrial environment. It may
be difficult to ensure electromagnetic
compatibility in a domestic environment.
INSTALLATION AND USE
The user is responsible for installing and
using the plasma equipment according to
the manufacturer's instructions. If
electromagnetic disturbances are
detected then it shall be the responsibility
of the user to resolve the situation with the
technical assistance of the manufacturer.
In some cases this remedial action may be
as simple as earthing the cutting circuit,
see
Earthing of Workpiece
. In other cases
it could involve constructing an
electromagnetic screen enclosing the
power source and the work complete with
associated input filters. In all cases
electromagnetic disturbances must be
reduced to the point where they are no
longer troublesome.
ASSESSMENT OF AREA
Before installing the equipment the user
shall make an assessment of potential
electromagnetic problems in the
surrounding area. The following shall be
taken into account:
a. Other supply cables, control cables,
signalling and telephone cables; above,
below and adjacent to the cutting
equipment.
b. Radio and television transmitters and
receivers.
c. Computer and other control equipment.
d. Safety critical equipment, for example
guarding of industrial equipment.
e. Health of the people around, for
example the use of pacemakers and
hearing aids.
f. Equipment used for calibration or
measurement.
g. Immunity of other equipment in the
environment. User shall ensure that other
equipment being used in the environment
is compatible. This may require additional
protection measures.
h. Time of day that cutting or other
activities are to be carried out.
The size of the surrounding area to be
considered will depend on the structure of
the building and other activities that are
taking place. The surrounding area may
extend beyond the boundaries of the
premises.
METHODS OF REDUCING
EMISSIONS
Mains Supply
Cutting equipment should be connected
to the mains supply according to the
manufacturer's recommendations. If
interference occurs, it may be necessary
to take additional precautions such as
filtering of the mains supply.
Consideration should be given to
shielding the supply cable of permanently
installed cutting equipment, in metallic
conduit or equivalent. Shielding should be
electrically continuous throughout its
length. The shielding should be
connected to the cutting mains supply so
that good electrical contact is maintained
between the conduit and the cutting power
source enclosure
Maintenance of Cutting Equipment
The cutting equipment should be routinely
maintained according to the
manufacturer's recommendations. All
access and service doors and covers
should be closed and properly fastened
when the cutting equipment is in
operation. The cutting equipment should
not be modified in any way except for
those changes and adjustments covered
in the manufacturer's instructions. In
particular, the spark gaps of arc striking
and stabilizing devices should be adjusted
and maintained according to the
manufacturer's recommendations.
Cutting Cables
The cutting cables should be kept as short
as possible and should be positioned
close together, running at or close to the
floor level.
Equipotential Bonding
Bonding of all metallic components in the
cutting installation and adjacent to it
should be considered. However, metallic
components bonded to the workpiece will
increase the risk that the operator could
receive a shock by touching these metallic
components and the electrode at the
same time. The operator should be
insulated from all such bonded metallic
components.
Earthing of Workpiece
Where the workpiece is not bonded to
earth for electrical safety, nor connected
to earth because of its size and position,
for example, ship's hull or building
steelwork, a connection bonding the
workpiece to earth may reduce emissions
in some, but not all instances. Care should
be taken to prevent the earthing of the
workpiece increasing the risk of injury to
users, or damage to other electrical
equipment. Where necessary, the
connection of the workpiece to earth
should be made by a direct connection to
the workpiece, but in some countries
where direct connection is not permitted,
the bonding should be achieved by
suitable capacitances selected according
to national regulations.
Note. The cutting circuit may or may not be
earthed for safety reasons. Changing the
earthing arrangements should only be
authorized by a person who is competent
to assess whether the changes will
increase the risk of injury, for example, by
allowing parallel cutting current return
paths which may damage the earth
circuits of other equipment. Further
guidance is given in IEC TC26 (sec)94
and IEC TC26/108A/CD Arc Welding
Equipment Installation and Use.
Screening and Shielding
Selective screening and shielding of other
cables and equipment in the surrounding
area may alleviate problems of
interference. Screening of the entire
plasma cutting installation may be
considered for special applications.
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