LN-15
.THEORY OF OPERATION
E-4 E-4
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FIGURE E.4 – WIRE FEED SPEED CONTROL & FEEDBACK
WIRE FEED SPEED CONTROL AND
FEEDBACK
The combination of the Procedure Switch and the Wire
Feed Speed control provide a command voltage for
the Feed Head Control Board. The Hall Effect module
(Tach) monitors the motor RPM and outputs a digital
voltage frequency “feed back” that is delivered to the
Feed Head Board.
When operating in the constant voltage (CV) mode the
Feed Head Board monitors the feedback signal and
compares it to the command voltage and delivers the
appropriate armature voltage to the wire feed motor.
In this manner a constant wire feed speed is main-
tained.
When the LN-15 is connected to a constant current
(CC) power source a variable wire feed speed is desir-
able to compensate for the varying arc voltages asso-
ciated with the constant current process. To accom-
plish this the Feed Head Board monitors the command
voltage, the feed back signal from the Hall Effect mod-
ule and the arc voltage. These three factors are com-
pared and the appropriate armature voltage is applied
to the wire feed motor to compensate for the varying
arc lengths and associated arc voltages.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
