ESAB LHJ 750, Instruction Manual, Page: 18 / 44

18
LHJ 750
All electrical connections must be firmly tightened to avoid sparking risks, overheating or circuit voltage
drop.
The grounding terminal is connected to the RECTIFIER chassis. It must
be connected to an efficient grounding point of the general power
supply system. DO NOT connect the grounding conductor of the input
cable to any of the terminals of the ON/OFF switch, which would put the
machine chassis under electrical tension.
IMPORTANT !
NOTE : DO NOT USE THE NEUTRAL OF THE POWER SUPPLY
SYSTEM FOR GROUNDING .
6.4)Welding circuit
The good functioning of a LHJ 750 also depends on the use of an insulated copper welding cable, which
must be the shortest possible and compatible to the considered application(s), it must also be in good shape
and firmly connected to its terminals; Electrical connections in the to-be-welded piece or in the work station
and in the set "negative" terminal must be firm.
Whatever the length (the shortest possible) and whatever the used welding current, the welding cable must
correspond to the maximum current which the used RECTIFIER can supply at power factor 60%.
Welding circuit electrical strength causes voltage drops which add to Rectifier natural internal drop,
reducing the arc voltage and the maximum available current making the arc unstable.
7) OPERATION
After connecting the LHJ 750 to the power supply system and connecting the electrode holder cable and the
work clamp, proceed to the following operations::
1) Place the ON/OFF switch on the ON position, the pilot lamp is on; the fan engine starts creating an air flow
which is needed for the machine refrigeration.
2) Preset the welding current through the crank. The clockwise rotation increases the current value;
anti clockwise rotation decreases current value.
crank
NOTE : the welding parameters value basically depend on the material and
electrode diameter in use, on the thickness of the to-be-welded piece as well
as on the welding position.
3) Open the arc and, if necessary, readjust current.