ESAB LAB 320, Instruction Manual, Page: 18 / 52

NOTE: In the Power Source LAB 475, the duty cycle is reinforced to 70%.
The duty cycle of 100% means that the unit can supply welding current specified (see table 4.1) non-stop,
that is, without any need of rest.
In a welding machine, the duty cycle allowed increases up to 100% once the welding current used
decreases, inversely, the duty cycle allowed decreases once the welding current increases up to the
maximum current range.
LAB 320
LAB 475
18
3) DUTY CYCLE
The duty cycle refers to the duty factor (F.t.) the reasoning, in percentage, between the period of time in
which the welding machine can supply a certain maximum welding current(loading time) and a reference
time; according to international standards, this reference time is of 10 minutes.
The Power Sources LAB units are characterized by 2 duty cycles: The nominal duty cycle with a value of
60% which corresponds to the duty capacity of the machines in their maximum current range, the duty cycle
and the duty cycle of 100%.
The duty cycle of 60% means that the machine supplies its maximum welding current at periods of 6 min.
(loading), each period is then followed by a resting period (the machine does not supply welding current) of
4 min. (6 + 4 = 10 min.), simultaneously, and not exceeding the internal temperature limit of the components,
according to their design and project.The same reasoning is applied to any value of the duty cycle.
4) TECHNICAL DATA
The table 4.1 indicates the authorized loading for the Sources LAB 320 and LAB 475.
TABLE 4.1
Maximum current (A)
Empty voltage range (V)
ABNT Standard
Nominal current (A)
LAB 320
250
I
17 - 44
LAB 475
I
17 - 52
400
Dimensions (W x D x H –mm)
Duty cycle (%)
Current (A)
Voltage (V)
Electric feeding(V-60 Hz)
Nominal apparent power (KVA)
Thermal class
Weight (kg)
Authorized loadings
60 80 100
320 280 250
220 / 380 / 440
505 x 1065 x 885
F ( 155 C )
o
30.0 28.0 26.0
11.5
153
70 80 100
475 450 400
38.0 36.5 34.0
220 / 380 / 440
17.5
505 x 1065 x 885
F ( 155 C )
o
180
320 475
The fan of the LAB sources guarantees their effective refrigeration; the power rectifier bridge, largely
dimensioned, assures the great performance at industrial regime.
The LAB sources cabinet is sturdy and easy to move around the work place once it has handles, wheels,
castors and lifting eye, a platform to place the shielding gas cylinder with capacity to up to 20 litres, making it
possible to be move together with the source.