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.
c)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.
1.If the LN-9 still shuts down, go to Step b. below.
2.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.
1.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.
2.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.
