Miller Electric KC237900 - Manual (Page 22)

OM-530 Page 18
4-17. PERCENTAGE DOWNSLOPE RATE CON-
TROL (Electroslope Models Only) (Figure 4-1)
t
PERCENTAGE
DOWNSLOPE
RATE
0.25-20 SEC.
0.25-20s
The PERCENTAGE DOWNSLOPE RATE control is
calibrated in percent and can be adjusted for a down-
slope rate of approximately .25 (FAST) to 20 (SLOW)
seconds. The settings of this control are comparable to
the PERCENTAGE UPSLOPE RATE control and deter-
mine the time rate at which weld amperage will de-
crease to the setting of the PERCENTAGE FINAL AM-
PERAGE control.
IMPORTANT: This control may be adjusted while
welding.
4-18. PERCENTAGE FINAL AMPERAGE CONTROL
(Electroslope Models Only) (Figure 4-1)
A
PERCENTAGE
FINAL
AMPERAGE
The PERCENTAGE FINAL AMPERAGE control ad-
justs the welding amperage at the finish of the weld and
operates on the same principle as the PERCENTAGE
INITIAL AMPERAGE control. The final amperage can-
not be higher than the weld amperage provided by TIG-
Unit.
IMPORTANT: This control may be adjusted while
welding.
4-19. PREFLOW TIME CONTROL & SWITCH
(Optional) (Figure 4-1)
t 1
PREFLOW TIME
WARNING: ELECTRIC SHOCK can kill; UN-
EXPECTED HIGH FREQUENCY DURING
PREFLOW can cause serious injury and
equipment damage.
•
Do not allow electroslope switch or other unit
control switch to be maintained closed during
preflow time.
•
Always close and immediately open control
switch to ensure that high frequency will not be
present during preflow.
If the unit is equipped with the optional electro-
slope and preflow timer, it is possible to have
high frequency present during preflow without
machine contactor energized.
An adjustable 0 to 15 second coolant-gas PREFLOW
TIME control can be provided for controlling the period
of time shielding gas and coolant flows before the arc is
initiated. The PREFLOW TIME control governs the op-
eration of a preflow timer within the TIG-Unit.
Rotating the control in a clockwise direction increases
the preflow time. The scale surrounding the PREFLOW
TIME control is calibrated in seconds to aid in the selec-
tion of a preflow time period suited to the individual weld-
ing operation.
As soon as the remote contactor control switch has
been closed, the preflow timer begins to time out the se-
lected period of preflow time. Once the timer has timed
out, the gas and coolant valves remain open and the
contactor closes providing weld power. The timer auto-
matically resets and is ready for another weld cycle
whenever the contactor is opened.
When coolant-gas preflow is desired, the PREFLOW
TIME switch must be placed in the ON position. Con-
versely, by placing the PREFLOW TIME switch in the
OFF position and rotating the PREFLOW TIME control
to minimum, coolant-gas preflow is not available.
WARNING: ELECTRIC SHOCK can kill.
•
Do not touch live electrical parts.
•
Set PREFLOW TIME control (if applicable) to
0 (minimum) when not using the preflow device.
The preflow device (if applicable) is always active even
though the PREFLOW TIME switch is in the OFF posi-
tion.
4-20. SPOT TIME CONTROL AND SWITCH
(Optional) (Figure 4-1)
t
SPOT TIME
An adjustable 0 to 5 second SPOT TIME control can be
provided for controlling the period of time weld power is
available for spot welding. The SPOT TIME control gov-
erns the operation of a spot timer within the TIG-Unit.
Rotating the control in a clockwise direction increases
the spot time. The scale surrounding the SPOT TIME
control is calibrated in seconds to aid the selection of a
spot time period suited to the individual welding opera-
tion.
When spot welding is desired, the SPOT TIME switch
must be placed in the ON position. Conversely, by plac-
ing the SPOT TIME switch in the OFF position, spot
welding is not available, despite the position of the
SPOT TIME control.
The spot weld timer begins to time out as soon as an arc
is initiated. When the time set on the SPOT TIME control
has elapsed, weld output is cut off and the postflow timer
starts.
Upon closure of the remote contactor control switch, the
operator may proceed with establishing an arc provided
that the preflow timer, if applicable, has timed out. As