Lincoln Electric IM812-A manual Automatic Protection Shutdown, Overvoltage Shutdown

B-7 OPERATION B-7

CC(formerly VV) power sources, on the other hand, permit the arc voltage to decrease with increases in welding current. The output characteristics of these power sources can range from a “drooping slope,” which provide minor arc voltage changes with weld current variations, to “steep slope” which provide broad voltage changes with only minor current variations. The steeper the slope the more difficult it becomes to maintain arc voltage stability with a constant wire speed open arc process.

To aid in stabilizing the arc voltage when welding on

CCpower sources the LN-35 is provided with a VV (CC) wire feed mode. This arc voltage sensing feed mode decreases (or increases) the wire speed when the arc voltage decreases (or increases). However, if the electrode shorts to the work, the arc voltage will essentially drop to zero and the short circuit current supplied by the CC power source may not provide enough power to re-establish the arc (especially with steeper slope machines). Under this condition the LN- 35 feeder will stop, as if the trigger was released, and not restart until the short has been opened.

Arc shorting is more difficult to avoid when using a CC power source, and requires a more refined operator technique than when using a CV power source. Improved performance can be obtained o n C C p o w e r s o u r c e a p p l i c a t i o n s w i t h i n t h e following guidelines:

1.Flatter slope power sources with higher arc force (short circuit current) will improve performance over steep slope machines. The steeper the slope, the more critical it is to hold proper electrode stickout to maintain arc stability . Welding techniques, such as weaving, will be more difficult to control. Use the highest output current tap or setting capable of providing the voltage adjustment required for the procedure.

AUTOMATIC PROTECTION SHUTDOWN

The LN-35 control provides automatic electronic protection circuits which shut down the LN-35 for excessively high power source open circuit voltage or excessive motor overload.

OVERVOLTAGE SHUTDOWN

If the power source open circuit voltage exceeds about 110-120 volts, the LN-35 will not operate until the power source voltage drops below about 102-110 volts.

MOTOR OVERLOAD SHUTDOWN

If excessive motor overload occurs (due to prolonged excessive feeding force, jammed drive rolls or shorted motor leads), the LN-35 will shut down within a few seconds after the overload occurs.

The shutdown will reset automatically when the gun trigger is released, but will reoccur if the overload situation is not remedied.

LN-35