2. Specifications
WMD078TE0PAA07
11
2.5 Rated duty cycle
The rated duty cycle of this welding machine is
60 %. This means that the machine can weld for
a total of 6 minutes out of any 10 minutes at the
rated current, and then must cool down during
the remaining 4 minutes to prevent overheating.
As shown on the above figure, the allowable duty
cycle varies with the output current. A duty cycle on
the curved line can be calculated using the follow-
ing formula.
Note
•
Observe the lowest allowable duty cycle of
the welding system components (typically
either the welding machine or the torch).
•
Exceeding the allowable duty cycle will cause
the unit to stop automatically (with error
displayed) or burn.
•
If the ambient temperature is higher than 40
°C, limit the duty cycle to a level lower than
the result of the formula.
•
Output current values for pulsed welding are
the average of the base and peak current
values.
2.6 Static characteristics and
thermal protection
Static characteristics
(Constant-voltage characteristics)
Thermal protection
Welding power source is equipped with a ther-
mal protection device near the heat sink of
IGBT and reactor to monitor the temperature.
The thermal protection functions when the
welding power source goes into an abnormal
temperature rise condition and stops the out-
put.
* Do not use the welding power source under
the following conditions.
•
At the output voltage above the rated
value.
•
With the suction opening blocked.
•
Ambient temperature is above 40
°C.
•
If the cooling fan does not rotate.
2.7 Functions of cooling fan
•
The cooling fan starts its rotation in 13
seconds after turning on the power switch.
•
The cooling fan rotates at low speed in the
standby state.
•
The cooling fan stops its rotation to
conserve energy if the standby state
continues for 7 minutes or longer.
•
The cooling fan rotates at high speed once
welding operation starts.
CAUTION
Accumulated dust on the cooling fan(s),
heat sinks, main semiconductor(s), or
windings can reduce allowable duty cycle
or allowable weld current, which can
cause deterioration or burnout of the
welding machine. Clean these sections
periodically.
Output current (A)
100
60
0
400
30
Usable range
Duty cycle (%)
308
(Calculate duty cycle
using formula)
(Rated duty cycle)
60 %
Up to 308 A:100 %
Allowable duty cycle vs. Output current
(10-minute cycle, ambient temp. 40 °C)
Actual Output Current
x
Rated Output Current
Duty Cycle =
(%)
(%)
2
Rated
Duty Cycle
Allowable
80
70
60
50
40
30
20
10
0
0
50
100 150 200 250 300 350
34 V
Current (A)
400
90
Voltage (V)
