Automatic, Shutdown, Topic – Lincoln Electric LN-9 SVM127-A User Manual

Page 28: Automatic shutdown, Operation

If such a grounding lead fault occurs, the meter will still
be on and will be reading. The trigger circuit will not
operate, however. To release the circuit, press the
"GLP Reset" button. See

Figure B.1 or B.2 for the

location of this button.

The following precautions are recommended to avoid
GLP shutdown:

• Do not allow the electrode to contact the case of the

wire feeder or uninsulated part of its wire reel stand
when the gun trigger is activated.

• Be sure that all work lead connections to the work

make tight metal-to-metal electrical contact.

• Do not allow excess input cable or work cable to be

placed closer than 3 feet to the wire feeder.

• Do not coil excess input cable assembly or use an

uncoiled assembly as shipped from the factory.
Instead, loop excess length back and forth in 3 to 6
foot straight lengths. Coiling the input cable results in
a transformer action between the electrode conductor
cable and ground lead in the multiconductor cable
and the ground lead in the multiconductor control
cable. This can cause current to flow in the ground
lead, which will falsely activate the GLP.

AUTOMATIC SHUTDOWN

If the LN-9 voltage control is unable to supply the SET
value of arc voltage while welding, the automatic shut-
down circuit will activate. This protection circuit imme-
diately returns the LN-9 control to idle state within a few
seconds after the arc voltage discrepancy occurs.

Typical causes for the activation of this protective shut-
down circuit are as follows:

a) SET value of arc voltage is outside the power

source range.

b) Power source voltage control not set for REMOTE.

Misconnection of LN-9 control cable leads to
power source.

d) Incorrect weld polarity connections, or settings, at

the LN-9 or the power source.

e) Lost connection of LN-9 voltage sensing leads

(#67 and #21) between the arc and voltage control,
or a blown 1/8 amp fuse on the Voltage PC board.

Although out of range shutdown can occur with all
power sources when working with very low or very high
arc voltages, it is most likely to occur when using the
R3S models with somewhat limited voltage range of

the various taps. For instance, if the R3S-400 triangle
tap setting is for 31 volts, the range of control from the
remote circuit is approximately 7 volts, i.e., 27-1/2 to
34-1/2 volts at nominal input voltage. If the LN-9 con-
trols are set for 29 volts and the input voltage to the
R3S goes up, it may not be possible for the LN-9 con-
trol circuit to hold the 29 volts. The welding will shut
down. By changing to the 27 volt triangle setting, the
range will be approximately 23-1/2 to 30-1/2 volts, and
at high input voltage there will be sufficient control to
hold the SET arc voltage. On these machines, if the
LN-9 stops welding, follow this procedure:

a) Move the LN-9 voltage set point 2 volts lower than

the desired procedure and make a test weld.

If the LN-9 still shuts down, go to Step b. below.

If the LN-9 keeps welding, change the R3S tri-
angle setting to the next higher voltage and
reset the LN-9 set point to the desired proce-
dure. R3S is now set properly unless there is
a significant change in input voltage. Skip the
following step.

b) Move the LN-9 voltage set point 2 volts higher than

the desired procedure and make a test weld.

If the LN-9 now keeps welding, change the
R3S triangle setting to the next lower voltage
and reset the LN-9 set point to the desired pro-
cedure. R3S is now set properly unless there
is a significant change in input voltage.

If the LN-9 still shuts down, refer to the para-
graph below and the other possible causes
previously listed.

In some cases, it is also possible to hold the ACTUAL
button pressed while starting the arc. Before the LN-9
shuts down, the actual arc voltage can be read on the
digital meter. Comparing this reading to the SET read-
ing will tell what change in the range controls of the
power source is required to supply the desired voltage.
Should the meter read zero, check the connections of
LN-9 sensing leads #21 and #67. Should the meter
read a minus (-) voltage, the polarity connections or
settings at the LN-9 or power source are wrong.

The same general procedure can be used on other
power sources. For example, if the LN-9 keeps shut-
ting down and the other possible causes have been
checked, adjust the SET voltage higher and/or lower
than the desired voltage. Then you can determine
what change in the range controls of the power source
is required to supply the desired voltage.

OPERATION

B-8

LN-9 Wire Feeder