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SECTION 11:
VOLTAGE REDUCTION DEVICE (VRD)
11.01 VRD Specifications
Description
ARC MASTER
400 MST
Notes
VRD Open Circuit Voltage
15.3 to 19.8V
Open circuit voltage between welding terminals.
VRD Resistance
148 to 193 ohms The required resistance between welding terminals
to turn ON the welding power.
VRD Turn OFF Time
0.2 to 0.3 seconds The time taken to turn OFF the welding power once
the welding current has stopped.
11.02 VRD Maintenance
Routine inspection and testing (power source)
An inspection of the power source, an insulation resistance test and an earth resistance test shall be
carried out.
a)
For transportable equipment, at least once every 3 months.
b)
For fixed equipment, at least once every 12 months.
The owners of the equipment shall keep a suitable record of the periodic tests.
Note
A transportable power source is any equipment that is not permanently connected and
fixed in the position in which it is operated.
In addition to the above tests and specifically in relation to the VRD fitted to this machine, the
following periodic tests should also be conducted by an accredited Thermal Arc service agent.
Description
IEC 60974-1 Requirements
VRD Open Circuit Voltage
Less than 20V; at Vin=400V
VRD Turn ON Resistance
Less than 200 ohms
VRD Turn OFF Time
Less than 0.3 seconds
If this equipment is used in a hazardous location or environments with a high risk of
electrocution then the above tests should be carried out prior to entering this location.
