Tweco 1000 Merlin(Sept1999) - Manual (Page 42)

SERVICE 38 Manual 0-2731
D. Direction of Cut
In the torches, the plasma gas stream swirls as it leaves
the torch to maintain a smooth column of gas. This swirl
effect results in one side of a cut being more square than
the other. Viewed along the direction of travel, the right
side of the cut is more square than the left (Refer to Fig-
ure 5-4). To make a square-edged cut along an inside
diameter of a circle, the torch should move counterclock-
wise around the circle. To keep the square edge along an
outside diameter cut, the torch should travel in a clock-
wise direction.
Right Side
Cut Angle
Left Side
Cut Angle
A-00512
Figure 5-4 Side Characteristics Of Cut
E. Dross
Generally when dross is present on carbon steel, it is re-
ferred to as either "high speed or slow speed dross".
"High speed dross" usually forms a narrow bead along
the bottom of the cut edge and is very difficult to remove.
"Slow speed dross" will be in larger quantities but does
not adhere tightly to the cut edge and can be easily re-
moved.
When cutting a troublesome steel, it is suggested that the
torch travel speed be reduced to produce "slow speed
dross". Any required cleanup can then be done by scrap-
ping, not grinding.
Dross present on top of the plate (top spatter), is normally
caused by a slow torch travel speed or too high of a torch
standoff distance.
5.05 Troubleshooting Guide
General
Troubleshooting and repairing this unit is a process which
should be undertaken only by those familiar with high
voltage high power electronic equipment.
WARNING
There are extremely dangerous voltage and power
levels present inside this unit. Do not attempt to
diagnose or repair unless you have had training in
power electronics measurement and troubleshoot-
ing techniques.
Basic Troubleshooting
This manual covers a basic level of troubleshooting that
requires limited dissasembly and measurements. If ma-
jor complex subassemblies are faulty, the unit must be
returned to an authorized service center for repair.
Follow all instructions as listed and complete each sec-
tion in the order presented. For major troubleshooting
and parts replacement procedures refer to Merlin 1000
Power Supply Service Manual 0-2732.
How to Use This Guide
The following information is a guide to help the Cus-
tomer/Operator determine the most likely causes for
various symptoms.
This guide is set up in the following manner:
X. Symptom (Bold Type)
Any Special Instructions (Text Type)
1. Cause (Italic Type)
a. Check/Remedy (Text Type)
Locate your symptom, check the causes (easiest listed first)
then remedies. Repair as needed being sure to verify that
unit is fully operational after any repairs.
A. AC Power LED OFF
1. Switch at customer's main power panel in OFF posi-
tion.
a. Close main power panel switch
2. Input power not properly connected to customer's main
power panel
a. Check that input power is present and unit is
properly connected (refer to Section 3.04, Input
Power Connections)
3. Customer's main power line fuse(s) blown
a. Check main power panel fuse(s) and replace as
required.