Tweco 300Pi Transtig Welding Inverter - Manual (Page 21)

TRANSTIG 300Pi
Manual 0-5309 3-3 INSTALLATION, OPERATION AND SETUP
5. Earthing of the Workpiece
Where the workpiece is not bonded to earth for electrical safety, nor connected to earth because of it’s
size and position, e.g. 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 direct connection to the
workpiece, but in some countries where direct connection is not permitted, the bonding should be
achieved by suitable capacitance, selected according to national regulations.
6. Screening and Shielding
Selective screening and shielding of other cables and equipment in the surrounding area may alleviate
problems of interference. Screening the entire welding installation may be considered for special
applications.
3.06 Transtig 300Pi Power Source Controls, Indicators and Features
(Pulse)
A-12098
Art # A-12099_AB
Figure 3-1: Front Panel Figure 3-2: Rear Panel
1. VRD ON/OFF Indicator Lights
A VRD (voltage reduction device) is a hazard reducing device designed to reduce electric shock hazards
present on the output of welding power source when operating in MMAW (stick) mode. Note that the
presence of VRD should not be used as a substitute for the use of appropriate safety practices as indicated
in section one of this manual.
Both the green and red indicator lights only operate in MMAW (stick) mode.
The green VRD ON light illuminates (red light is off) when the VRD is active. Under this condition the open
circuit voltage of the unit is limited to below 10V DC, thus reducing the potential of serious electric shock
(such as when changing electrodes).
The red VRD OFF light illuminates (green light is off) when the VRD is inactive. Under this condition the
output voltage of the unit will be at welding potential which in some cases may exceed 25V DC.