Lincoln Electric IM703-A manual Pulse Background Current Control

B-6 OPERATION B-6

•In 4-Step position allows welding without continu- ously holding the start switch trigger. The arc start switch functions in the following manner:

1.Closing switch starts preflow, then arc starts at Minimum (Start) setting level (See Item 7). If the trigger is maintained closed after preflow time the output remains at the Start level until it is released.

2.Opening switch initiates fixed (0.5 sec.) ramp time from Start setting level to Weld setting.

3.Reclosing switch initiates Downslope ramp time setting (See item 17) from Weld setting down to the Crater-fill level (See Item 7) of the machine.

4.Reopening switch after Downslope time holds Crater-fill level until switch opens, then stops the arc and initiates the Postflow Time (See Item 9). Or, reopening switch during Downslope time immediately stops the arc and initiates the Postflow.

Note: See Section B-7 for 4-Step operation during Downslope with Restart feature selected to be enabled, instead of disabled (as shipped).

13.PULSE MODE SWITCH – Turns on the Pulse Mode as indicated by the Green panel light turning on.

•Pulsing provides a Peak current level set by REMOTE and/or LOCAL control of the output cur- rent (See Item5), for a time determined by the Pulse Frequency Control setting (See Item 14) and the % ON Time (See Item 15). The balance of the cycle time is at the Background Current level (See Item 16).

•Pulsing begins after upslope when the output cur- rent rises above the Background Current level and ends when the output current drops below this level.

14.PULSE FREQUENCY CONTROL – This knob is used to set the Pulse Frequency over the peak pulse range of about 0.1 pps to 20 pps. (One pulse cycle time = 1/pps = 10 to .05 sec. range.)

15.PULSE % ON TIME CONTROL – This knob con- trols the duration of the peak current as a percent- age (5% to 95%) of one pulse cycle. The balance of the cycle time will be at the Background Current setting. (See Item 16)

16.PULSE BACKGROUND CURRENT CONTROL –

This knob controls the level of the Background Current as a percentage (MIN.-100%) of the Peak (REMOTE and/or LOCAL) output level (See Item

6)down to the Minimum Output setting (See Item

17.DOWNSLOPE TIME– This knob is used to set the time, over the range of zero to about 10 seconds, to ramp down from weld setting to Crater-fill level (See Item 7).

•If the arc goes out after the Downslope time is initi- ated, the Downslope time is interrupted and the Postflow time is initiated. This prevents Hi-Freq re- initiation during ramp down crater fill

•When using an Amptrol remote control, where the downslope is controlled by the operator down to the crater-fill level, the Downslope time should be set to zero so as not to have the Downslope time delay when the arc start switch is opened.

18.HIGH FREQUENCY INTENSITY CONTROL (NOT SHOWN)– Allows setting the lowest intensity which still gives good TIG arc starting with minimized Radio Frequency Interference (RFI). Control knob is located on a recessed panel near the easy acces- sible spark gap side panel. As shipped, the control is set to minimum.

PRECISION TIG 375