Tweco 3000 Merlin - Manual (Page 16)

INTRODUCTION 2-2 Manual 0-2532
4. Output Power
Continuously adjustable by potentiometer from 50
to 150 amps
5. Duty Cycle
100%
6. Pilot Modes
Auto-Restart, Pre-Flow Delay, Recycle
7. CNC Signals
Enable Start/Stop, OK-to-Move, Pilot Sensing Relay
(PSR), Full CNC Available with Remote
8. Coolant Pressure
Internal Service-adjustable
130 psi (8.8 bar) at zero flow
120 - 125 psi (8.2 - 8.5 bar) at 0.6 gpm (2.6 lpm)
9. Coolant Flow Rate
0.5 gpm (2.2 lpm) with 150 feet of total torch and
torch leads at 70°F (21°C)
NOTE
The flow rate varies with lead length, torch
configuration, ambient temperature, amperage
level, etc.
10. Cooling Capacity
4,000 to 10,000 BTU
NOTE
Maximum value based on “free flow” condi-
tion.
11. Coolant Reservoir Capacity
2 gallons
Capable of handling a total of 150 feet of torch lead length
12. Power Supply Dimensions
Enclosure Only -
Width: 24.12 in (0.61 m)
Height: 38.38 in (0.98 m)
Depth: 34.25 in (0.87 m)
Fully Assembled -
Width: 28.50 in (0.72 m)
Height: 43.38 in (1.10 m)
Depth: 43.75 in (1.11 m)
13. Weight of Power Supply Only
678 lbs (308 kg)
2.04 Theory Of Operation
A. Plasma Arc Cutting and Gouging
Plasma is a gas which is heated to an extremely high
temperature and ionized so that it becomes electrically
conductive. The plasma arc cutting process uses this
plasma gas to transfer an electric arc to a workpiece.
The metal to be cut is melted by the intense heat of the
arc and then blown away by the flow of gas. Plasma arc
gouging uses the same process to remove material to a
controlled depth and width.
With a simple change of torch parts, the system can also
be used for plasma arc gouging. Plasma arc gouging is
used to remove material to a controlled depth and width.
B . Input and Output Power
The Power Supply accepts input voltages from 200 to
575V, 50 or 60 Hz, three-phase. Input voltages are set
by an internal changeover in the unit. The unit converts
AC input power to DC power for the main cutting arc.
The negative output is connected to the torch electrode
through the negative torch lead, and the positive output
connects to the workpiece through the work cable.
C. Pilot Arc
When the torch is activated there is a two second gas
pre-flow, followed by a uninterrupted DC pilot arc estab-
lished between the electrode and tip. The pilot arc is
initiated by a momentary high frequency pulse from the
Arc Starter Box. The pilot creates a path for the main arc
to transfer to the work. When the main arc is estab-
lished, the pilot arc shuts off. The pilot automatically
restarts when the main arc stops, as long as the torch
remains activated.
NOTE
For the arc to restart automatically, AUTO RE-
START must be enabled at switch settings
inside the Power Supply.
D. Main Cutting Arc
The Power Supply accepts 50 or 60 Hz three-phase line
input. An internal changeover switches input line volt-
ages in three ranges, for 200/220/230V, 380/415/460V,
or 500/575V operation. The power supply converts AC
input power to DC power for the main cutting arc. The
negative output is connected to the torch electrode
through the negative torch lead. The positive output is
connected to the workpiece via the work cable and clamp
connection.