Tweco Merlin 6000 Master PS - Manual (Page 35)

Manual 0-2568 3-17 INSTALLATION PROCEDURES
Master and Slave Power Supply pilot resistors are ini-
tially set at the factory and may need to be adjusted to
the customer's input power (see Notes).
NOTES
The instructions in this Sub-Section apply to the
Master Power Supply only.
To adjust the Slave Power Supply pilot resistor,
refer to the Manual supplied with the Slave Power
Supply.
WARNING
Disconnect primary power at the source before as-
sembling or disassembling power supply, torch
parts, or torch and leads assemblies.
The pilot current consists of two parts:
1) Minimum or “background” level
2) Pulse or peak level
The background level has to be high enough that the pi-
lot will not sputter or go out, but not too high to cause
excessive wear of the torch consumables. Adding pulses
of current on top of the background current allows greater
arc transfer distance without increasing the torch part
wear. The amount of pilot current is determined by the
value of the pilot resistors and the open circuit voltage
which varies with the input line voltage. Both the Mas-
ter and the Slave Power Supplies should be adjusted the
same. Wire #99 tap sets the background level and wire
#150 tap sets the pulse level. To set the pilot background
and pulse levels use the following procedure:
1. Remove the left and right side panels of the Mas-
ter 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
Clamp
A-01853
Wire
#150
Pilot Resistor
R21
Pilot Resistor
R22
Wire
#74
Wire #99
Wire
#96
Temp
Switch
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. Locate the transformer voltage range (200-
230V, 380-460V or 500-575V)
b. Find the voltage that is nearest what was mea-
sured above.
c. Note the ohms value for the voltage. Example:
If the transformer range is 380-460, and the
measured voltage is 455, then the pilot resis-
tor value is 6 ohms.
NOTE
Voltages that are from 200 to 210V, 410 to 420V
and 510 to 520V required 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.