Smaw Module LHT-8 and 9
Smaw Module LHT-8 and 9
Smaw Module LHT-8 and 9
Department of Education
Region VII, Central Visayas
Division of Cebu Province
DISTRICT OF BALAMBAN II
V. Procedure
A. Readings
WELDING POWER SOURCE
The function of a power source is to provide the voltage necessary to maintain an arc
between the electrode and the workpiece and a sufficient supply of electric to melt the surface of
the workpiece and the end of the electrode.
Power sources may supply direct current (DC) or alternating current (AC) to the electrode.
AC is the most common power supply due to the lower cost and simplicity of the welding machine,
however, DC has some advantages. The DC arc is noticeably more stable when using certain
types of electrodes DC is better for sheet metal.
ALTERNATING CURRENT WELDING CIRCUIT
An AC only SMAW power source is the most economical type of welding power source
available. Because of the alternating characteristic of the current, however, the resulting arc and
weld will tend to have more spatter, less penetration, and more arc outages than a weld made with
direct current. One situation when alternating current would work better than direct current is if the
operator is encountering magnetic arc blow.
DIRECT CURRENT WELDING CIRCUIT
DIRECT CURRENT is the most common current choice for stick welding. The current flows
in one direction only and has many advantages over alternating current for the stick process.
These
advantages include: fewer arc outages, less spatter, easier arc starting, less sticking, and better
control in out-of-position welds.
The polarity of the direct current welding arc or the direction of electrical current flow is very
important. When the electrode cable is connected to the power sources positive output connection
and the work cable is connected to the negative output connection this is a DCEP (Direct Current
Electrode Positive) or Direct Current Reverse Polarity connection. When the electrode cable is
connected to the negative and the work cable is connected to the positive this is a DCEN ( Direct
Current Electrode Negative) or Direct Current Straight Polarity connection.
For SMAW, the DCEP connection is used most often. It provides for the best penetration
and bead profile. For this reason most electrodes are made to weld with DCEP.
Using a DCEN connection for SMAW will result in a narrow bead with little penetration. This
connection works well when welding on sheet metal or for hard surfacing electrodes.
BASIC PARTS OF WELDING POWER SOURCE
The basic parts of a power source are shown in Fig. 1.1 the function of these parts.
Lever Switch
TRANSFORMER RECTIFIER
DC INVERTER TYPE
WELDING CABLES
ELECTRODE HOLDER
Exercise 2
Directions: Answer the questions below. Give the BEST answer.
1. In Direct Current Reverse Polarity, The electrode cable is connected to the __________?
2. a welding current that will result in a narrow bead with little penetration
3. a portable welding machine that is handy, quiet in operation, convenient and lower cost
4. welding machines that are less complex and expensive than other types
5. its function is to provide the voltage necessary to maintain an arc between the electrode and the
workpiece and a sufficient supply of electric to melt the surface of the workpiece and the end of
the electrode
C. Assessment/Application
I. Directions: Read the following carefully and choose the BEST answer.
1. What is the most economical type of welding power source available?
A) AC B) DC C) DCEN D) DCEP
2. it provides the current output reading of the welding machine
A) Current adjusting wheel B) Current range indicator
C) Lever Switch D) Power supply
3. A situation when alternating current would work better than direct current is?
A) Adjusting current B) Encountering magnetic arc blows
C) Fewer arc outages D) Less Spatter
4. a welding machine that has an internal combustion engine.
A) DC Generators B) DC Inverters C) Rectifiers D) Transformers
5. What polarity is used if the electrode cable is in the positive outlet?
A) AC B) DC C) DCEP D) DCSP
6. it provides/switches the machine ON/OFF whenever the machine needed for operation
A) Current adjusting wheel B) Current range indicator
C) Lever Switch D) Secondary winding terminals
7. it is a machine designed to provide either DC or AC outputs
A) DC Generators B) DC Inverters C) DC Rectifiers D) AC Transformers
8. Which of the following is NOT an advantage of a DC welding circuit?
A) easier arc starting B) fewer arc outages
C) less spatter D) more arc striking
9. In order to increase the current, the current adjusting wheel should be turned _______.
A) clockwise B) counter clockwise C) downward D) upward
10. What polarity is used if the electrode cable is in the negative outlet?
A) AC B) DC C) DCEP D) DCSP
11. welding machines that are less complex and expensive than other types
A) DC Generators B) DC Inverters C) DC Rectifiers D) AC Transformers
12. it is a machine designed to provide either DC or AC outputs
A) DC Generators B) DC Inverters C) DC Rectifiers D) AC Transformers
13. What is the polarity if the work cable is connected to the positive outlet?
A) AC B) DC C) DCEP D) DCSP
14. _____ provides electrode holder cable and return cable connections to the welding machine
A) Current adjusting wheel B) Current range indicator
C) Lever Switch D) Secondary winding terminals
15. What polarity provides the best penetration and bead profile?
A) AC B) DC C) DCEP D) DCSP
16. It connects to the welding cable then connects the welding current to the electrode.
A) clamp B) electrode C) electrode cable D) electrode holder
17. ________ is an external device that can be added to main equipment generating multiple
functions in order to make it more useful, versatile, or attractive
A) electrode B) electrode holder C) machine parts D) welding accessories
18. It connects the Grounding/Earthing Cable from the welding machine to the base metal.
A) electrode B) electrode cable C) electrode holder D) ground cable
19. Its function is to hold the electrode at desired angle.
A) electrode B) electrode cable C) electrode holder D) ground cable
20. _____ should be relatively light, fully insulated and sturdy enough to withstand continual
handling.
A) electrode B) electrode cable C) electrode holder D) ground cable
II. Directions: Draw a welding machine with its accessories and label each parts. Use the space
below.
Prepared by:
FELIX BERNAR R. MILAN Verified by:
Teacher I
SUSAN C. TRIBUNALO
Checked by: School Principal I
ROMMEL C. MELGAR
Subject Coordinator