Exothermic welding cannot be used on copper wire-to-steel connections because these are two different metals.
True or False?
Reference: Type of Ground Connectors, “Exothermic Weld Connectors,” Paragraph 1, Sentence 2
False
After igniting the powder in an exothermic mold, one should wait approximately ____ for the weld to cool and solidify before opening the mold.
a. 10 seconds
b. 15 seconds
c. 20 seconds
d. 30 seconds
Substation Construction Guidelines Textbook, Chap. 9, Pg. 307, Step 11
d. 30 seconds
The recommended ignition source for exothermic welding is a ____.
a. disposable cigarette lighter
b. flint-type spark generator
c. propane torch
d. wooden match
Reference: Type of Ground Connectors, “Safety,” Bullet 5
b. flint-type spark generator
The extreme temperatures of exothermic reactions produce temperatures of ____ in the crucible of the mold.
a. 2,500 °F
b. 3,000 °F
c. 3,500 °F
d. 4,000 °F
Substation Construction Guidelines Textbook, Chap. 9, Pg. 311, “Safety,” Paragraph 4, Bullet 1
d. 4,000 °F
Of the most commonly used connections, the ____ type presents the greatest hazards to the substation worker during installation.
a. bolted
b. exothermic weld
c. squeeze
d. wedge
Reference: Type of Ground Connectors, “Exothermic Weld Connectors,” Paragraph 1, Last Sentence
b. exothermic weld
When making connections in an existing substation, a person can be subject to electric shock when bridging across a point in the grid. Which of the following is the proper safety procedure?
a. Avoid putting oneself across the open point.
b. Use a temporary jumper before making the permanent connection.
c. Wear Class 2 rubber gloves to make the permanent connection.
d. Work from an insulated mat.
Substation Construction Guidelines Textbook, Chap. 9, Pg. 311, “Safety,” Paragraph 3
b. Use a temporary jumper before making the permanent connection.
Which of these statements regarding wedge type connections is true?
a. It is not necessary to clean the connection area.
b. The connection forms a molecular bond of the conductors being joined.
c. The connectors can be removed and re-used.
d. There are no temperature or weather restrictions.
Reference: Type of Ground Connectors, Figure 2, Caption
d. There are no temperature or weather restrictions.
IEEE 80 rates the maximum allowable temperature limits for welded connections on ground grids only.
True or False?
Reference: Type of Ground Connectors, “Introduction,” Paragraph 1, Sentence 4
False
A bonding of the conductors at a molecular level is the result of a(n) ____ type connection.
a. exothermic
b. hydaulic compression
c. parallel groove
d. wedge
Reference: Type of Ground Connectors, “Introduction,” Paragraph 2, Sentence 3
a. exothermic
After the area to be connected is cleaned, the application of conductive grease is necessary if ____ connectors are used. This type of connector is normally shipped dry.
a. C-clamp
b. fired wedge
c. mechanical wedge
d. thermoweld
Reference: Type of Ground Connectors, “Squeeze Connectors,” Paragraph 1, Sentence 2
a. C-clamp
When engineers select the type of connectors to be used, they take into account the maximum fault current that will be imposed on the connectors and the ____ of the connectors.
a. contact surface area
b. mechanical breaking strength
c. temperature limits
d. voltage rise during a fault event
Reference: Type of Ground Connectors, “Introduction,” Paragraph 1, Sentence 2
c. temperature limits
Over tightening of a mechanical wedge type connector is avoided by the ____.
a. bolt bottoming out in the casting well
b. bolt head that shears off when fully tightened
c. bolt head that stops flush with the casting
d. use of a torque wrench set at 40 psi
Reference: Type of Ground Connectors, “Wedge Connectors,” Paragraph 1, Sentence 4
b. bolt head that shears off when fully tightened
The presence of ____ in an exothermic mold will result in an explosion when the metal powder is ignited.
a. aluminum oxide
b. dirt
c. iron oxide
d. water
Reference: Type of Ground Connectors, “Safety,” Bullet 4, Sentence 1
d. water
The trademark name of a manufacturing company specializing in exothermic connections is ____.
a. Ampact
b. Cadweld
c. General Electri
d. Thermoweld
Reference: Type of Ground Connectors, “Exothermic Weld Connectors,” Paragraph 1, Sentence 2
b. Cadweld
The exothermic welding process uses powdered metals such as copper oxide and ____ to produce the chemical reactions necessary.
a. aluminum
b. magnesium
c. palladium
d. silver
Reference: Type of Ground Connectors, “Exothermic Weld Connectors,” Paragraph 2, Sentence 2
a. aluminum
A wedge connector produces a molecular bond with a current-carrying capability equal to or greater than that of the conductors being joined.
True or False?
Reference: Type of Ground Connectors, “Wedge Connectors”
False
A substation ground grid is typically constructed ____ below the finish grade.
a. 6” to 12”
b. 12” to 18”
c. 18” to 24”
d. 24” to 30”
Substation Construction Guidelines Textbook, Chap. 9, Pg. 303, “Below-Grade Connections,” Paragraph 1, Sentence 1
b. 12” to 18”
Graphite is used to make an exothermic mold.
True or False?
Substation Construction Guidelines Textbook, Chap. 9, Pg. 310, Picture D
True
Carbon traces found when inspecting exothermic connections is evidence of ____.
a. dirt in the mold cavity
b. oil on the cable strands
c. outdated chemicals
d. water in the cable strands
Source:
Substation Construction Guidelines Textbook, Chap. 9, Pg. 310, Picture D
b. oil on the cable strands
Cotton gloves should always be worn when making exothermic welds.
True or False?
Substation Construction Guidelines Textbook, Chap. 9, Pg. 305, “Tools Required,” Bullet 5
False
