Tweco 170 HF Weldskill - Manual (Page 18)

WELDSKILL 170 HF INVERTER
3-2 April 23, 2008
3.05 High Frequency Introduction
The importance of correct installation of high
frequency welding equipment cannot be
overemphasized. Interference due to high frequency
initiated or stabilized arc is almost invariably traced
to improper installation. The following information is
intended as a guide for personnel installing high
frequency welding machines.
!
WARNING: EXPLOSIVES
The high frequency section of this machine
has an output similar to a radio transmitter.
The machine should NOT be used in the
vicinity of blasting operations due to the
danger of premature firing.
!
WARNING: COMPUTERS
It is also possible that operation close to
computer installations may cause
computer malfunction.
3.06 High Frequency Interference
Interference may be transmitted by a high frequency
initiated or stabilized arc welding machine in the
following ways:
1. Direct Radiation: Radiation from the machine can
occur if the case is metal and is not properly
grounded. It can occur through apertures such
as open access panels. The shielding of the high
frequency unit in the Power Source will prevent
direct radiation if the equipment is properly
grounded.
2. Transmission via the Supply Lead: Without
adequate shielding and filtering, high frequency
energy may be fed to the wiring within the
installation (mains) by direct coupling. The energy
is then transmitted by both radiation and
conduction. Adequate shielding and filtering is
provided in the Power Source.
3. Radiation from Welding Leads: Radiated
interference from welding leads, although
pronounced in the vicinity of the leads, diminishes
rapidly with distance. Keeping leads as short as
possible will minimize this type of interference.
Looping and suspending of leads should be
avoided where possible.
4. Re-radiation from Unearthed Metallic Objects:
A major factor contributing to interference is re-
radiation from unearthed metallic objects close
to the welding leads. Effective grounding of such
objects will prevent re-radiation in most cases.
3.07 Electromagnetic Compatibility
!
WARNING
Extra precautions for Electromagnetic
Compatibility may be required when this
Welding Power Source is used in a
domestic situation.
A. Installation and Use - Users Responsibility
The user is responsible for installing and using the
welding equipment according to the manufacturer’s
instructions. If electromagnetic disturbances are
detected then it shall be the responsibility of the user
of the welding equipment to resolve the situation with
the technical assistance of the manufacturer. In some
cases this remedial action may be as simple as
earthing the welding circuit, see NOTE below. In other
cases it could involve constructing an electromagnetic
screen enclosing the Welding Power Source and the
work, complete with associated input filters. In all
cases, electromagnetic disturbances shall be reduced
to the point where they are no longer troublesome.
NOTE
The welding circuit may or may nor be
earthed for safety reasons. Changing the
earthing arrangements should only be
authorised by a person who is competent
to assess whether the changes will
increase the risk of injury, e.g. by allowing
parallel welding current return paths which
may damage the earth circuits of other
equipment. Further guidance is given in
IEC 974-13 Arc Welding Equipment -
Installation and use (under preparation).
B. Assessment of Area
Before installing welding equipment, the user shall
make an assessment of potential electromagnetic
problems in the surrounding area. The following shall
be taken into account
1. Other supply cables, control cables, signalling
and telephone cables; above, below and
adjacent to the welding equipment.
2. Radio and television transmitters and
receivers.