Hypertherm HT4001 Plasma Arc Cutting System - Manual (Page 237)

APPENDIX C
c-2
HT4001
Instruction Manual
EMC INTRODUCTION
This plasma cutting equipment 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 equip-
ment 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 manufacturers instructions.
If electromagnetic disturbances are
detected then it shall be the respon-
sibility 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 sur-
rounding 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
manufacturers recommendations. If
interference occurs, it may be necessary
to take additional precautions such as
filtering of the mains supply. Considera-
tion 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
manufacturers 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 manufacturers 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