Operation Manual

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A7 MIG Welder© Kemppi Oy 2018 1824
OPERATING MANUAL
4.5.1 Voltage source, levels and safety
The touch sensor provides eight software selectable DC voltage levels (see Table 4.19,
“Voltage levels”). The voltage level can be congured in the web user interface or the
setup panel. See Subsection 4.5.5, “Selecting output voltage” for more information on
the voltage level setup.
All levels have limited continuous power supply to ensure human safety. The 200 V
supply drops down under the 113 V level when loaded by a 5.6 kΩ resistor which is the
nominal DC resistance of the human body. In some cases, voltage levels above 113 V can
still cause minor harm, such as pain, to a person. Use the gate door safety switch with
touch sensor levels above 110 V.
The welder system features an arc measurement function which is performed between
the welding plus and minus poles near the welding arc using specic cabling and a
measurement circuitry. The measurement system inuences touch sensing when
the welding wire is used as a touch tool and when the arc measurement cables are
connected. The measurement system does not inuence touch sensing when the gas
nozzle is used as the touch tool.
The touch sensing is inuenced when
• the arc measurement cable between the power source and the wire feeder
(included in the cable set) is connected, but the arc measurement clamp from
the wire feeder to the workpiece is disconnected.
• the clamp is also connected. This situation is more harmful because it causes
false touch detection at certain voltage levels.
The Table 4.19, “Voltage levels” describes all setups and their relative voltage levels. The
accuracy of all values in the table except the nominal voltage is ±5 %.
Table 4.19 Voltage levels
Nominal
voltage
Voltage
(gas nozzle)
Voltage
(welding wire)
Voltage
(welding wire +
arc cable on)
Voltage
(welding wire +
arc clamp on)
50 V 55 V 54 V 54 V 50 V
80 V 80 V 80 V 77 V 74 V
110 V 110 V 110 V 105 V 87 V
150 V 150 V 150 V 130 V 89 V*
160 V 160 V 160 V 130 V 89 V*
170 V 170 V 170 V 130 V 89 V*
180 V 180 V 180 V 130 V 89 V*
200 V 200 V 200 V 130 V 89 V*
*Values cause false detection on touch sensor.
The power source and the touch sensing circuitry are galvanically isolated from the
other systems in the robot interface unit.