Voltage Reduction Device (Vrd); Vrd Specification; Vrd Maintenance - Thermal Arc ARCMASTER 300 AC/DC Service Manual

9

VOLTAGE REDUCTION DEVICE (VRD)

1

VRD Specification

ARC
Description MASTER
300ACDC
VRD Open 15.3 to
Circuit Voltage 19.8V
VRD 148 to 193
Resistance ohms
VRD Turn OFF 0.2 to 0.3
Time seconds
Table 9-1: VRD Specification
2

VRD Maintenance

Routine inspection and testing (power source):
An inspection of the power source should be car-
ried out.
a. For transportable equipment, at least once
every 3 months; and
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 fol-
lowing periodic tests should also be conducted by
an accredited Thermal Arc service agent.
Description IEC 60974-1 Requirements
VRD Open
Less than 20V; at Vin=400V
Circuit Voltage
VRD Turn ON
Less than 200 ohms
Resistanc
VRD Turn OFF
Less than 0.3 seconds
Time
Table 9-2: Periodic Tests
VOLTAGE REDUCTION DEVICE (VRD)
Notes
Open circuit voltage
between welding
terminals.
The required resistance
between welding
terminals to turn ON the
welding power.
The time taken to turn
OFF the welding power
once the welding current
has stopped.
9 – 1
If this equipment is used in a location or an envi-
ronment with a high risk of electrocution then the
above tests should be carried out prior to entering
this location.
The test of VRD is shown below:
1) In STICK welding mode, mark and then turn
potentiometer VR1 on PCB6 (WK-5549) all the
way to the left and turn on the electric shock
protector function (Voltage-Reduction-Device,
VRD).
2) Contactor function is put into the state of "ON"
by pushing Function button. Refer to section 6.
3) Verify the no-load voltage (OCV) using a DC
voltmeter. (The capability of the voltmeter
should be more than 100VDC.)
4) The normal no-load voltage is approximately
18V.
5) In STICK welding mode, mark and then turn
potentiometer VR1 on PCB6 (WK-5549) all the
way to the right and turn off the VRD.
6) Contactor function is put into the state of "ON"
by pushing Function button. Refer to section 6.
WARNING
Electric shock hazard. The unit will generate OCV
(Open Circuit Voltage) immediately when contactor
function is put into the state of on pushing Function
button at STICK mode.
7) Verify the no-load voltage (OCV) using a DC
voltmeter. (The capability of the voltmeter
should be more than 100VDC.)
8) The normal no-load voltage is approximately
65V.