Tweco Merlin 6000 Plasma Cutting CE Slave Power Supply - Manual (Page 24)

INSTALLATION PROCEDURES 3-8 Manual 0-2603
NOTES
The instructions in this Sub-Section apply to the
Slave Power Supply only.
To adjust the Master Power Supply pilot resistors,
refer to the Manual supplied with the Master Power
Supply.
The pilot current has to be high enough that the pilot will
not sputter or go out, but not too high to cause excessive
wear of the torch consumables. The amount of pilot cur-
rent is determined by the value of the pilot resistors and
the open circuit voltage which varies with the input line
voltage. Both the Slave and Master Power Supplies
should be adjusted the same. Wire #99 tap sets the pilot
current level. To set the pilot pilot current level use the
following procedure:
1. Remove the left and right side panels of the Mas-
ter Power Supply.
NOTE
The switches located on the Logic PC Board and
the Switching PC Board must be set the same as in
the Master Power Supply.
2. Locate and identify the pilot resistors (R16, R21
and R22) which are on a bracket in front of the
fan.
Wire
#96A
Pilot Resistor
R16
Clamp
A-02597
Pilot Resistor
R21
Pilot Resistor
R22
Wire
#74
Wire #99
Wire
#96
Figure 4-4 Location Of Pilot Resistors (Viewed
From The Front Of Power Supply)
3. Check the busbar configuration on the input ter-
minal board to determine which range the power
transformer is set for.
4. Measure the level of the AC line voltage being
supplied to the Power Supply.
5. To determine the recommended pilot resistor set-
ting use the following table as follows:
a. Find the voltage that is nearest what was mea-
sured above.
b. Note the ohms value for the voltage. Example:
If the measured voltage is 360, then the pilot
resistor value is 6 ohms.
NOTE
Voltages that are from 410 to 420V require values
from 8.5 or 9 to 4.5 ohms. If the voltage is near one
of these points it is best to set for the lower ohms
value.
The reason is because within each range the Power
Supply will automatically select a high or low tap
on the transformer secondary. This is based on
the input AC line voltage at the time the Power
Supply is turned ON. If the line voltage is near
one of these points the voltage might measure, for
example, 410 VAC and the pilot resistor setting
should be 9 ohms to have a good pilot. The next
time the system is turned ON, the input AC line
voltage may have gone up to 420VAC causing the
pilot to sputter because 420VAC requires setting
of 4.5 ohms.