Bending of Straight Copper
Terminals
Brazed
joint
Position of
tongue before
bending
NBAA Conference 2003
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Terminal Strips
4 Barriers to prevent adjacent studs
from contacting each other
4 Current should be carried by terminal
contact surface and not by stud
4 Studs anchored against rotation
4 Replace defective studs with studs
of same size and material, mount
securely, tighten terminal securing nut
NBAA Conference 2003
2
Terminal Strips, cont.
4 Mount strips so loose metallic objects
cannot fall across terminal
„
Provide spare stud for breaks and
future expansion
„
Inspect terminal periodically for loose
connections, metallic objects, dirt, and
grease accumulation
4
Can cause arcing, resulting in fire
or systems failure
NBAA Conference 2003
3
Terminals on circuit breakers
NBAA Conference 2003
4
Power feeder terminals
NBAA Conference 2003
5
Terminal Lugs
4Connect wiring to terminal block studs
4No more than 4 lugs, or 3 lugs and
a bus bar, per stud
4Lug hole size should match stud
diameter
Greatest diameter on bottom,
smallest on top
„ Tightening terminal connections
should not deform lugs
„
NBAA Conference 2003
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Terminal Lugs, cont.
4Aluminum lugs
„
Crimped to aluminum wire only
4
Special attention needed to guard
against excessive voltage drop at
terminal junction
• Inadequate terminal contact area
• Stacking errors
• Improper torquing
„
Use calibrated crimp tools
NBAA Conference 2003
7
Terminal
Stacking
(like materials)
Nut
Lock washer
Flat washer
Copper
terminal lugs
Terminal stud
NBAA Conference 2003
8
Terminal Stacking
(unlike materials)
Nut
Lock washer
Flat washer
Copper terminal
Flat
washers
Aluminum
terminals
Terminal stud
NBAA Conference 2003
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Terminal
Stacking
Methods
Crimp barrel
(belly up)
Nut
Lock
washer
Flat
washer
Crimp barrel
(belly down)
One-Sided Entry With Two Terminals
NBAA Conference 2003
10
Terminal
Stacking
Methods, cont.
Crimp barrel
(belly down)
in “V” split
Nut
Lock
washer
Flat washer
Crimp barrel
(belly up) in
center of “V”
One-Sided Entry With 3 Terminals
NBAA Conference 2003
11
Terminal
Stacking
Methods, cont.
Nut Lock washer
Flat washer
Crimp barrel
(belly up) in
“V” split
Crimp barrel
(belly down)
in “V” split
One-Sided Entry With 4 Terminals
NBAA Conference 2003
12
Terminal Tightening Hardware
Incorrect
Space
Correct
Nut
Lock
washer
Flat
washer
Lock washer
not compressed
Lock washer compressed
NBAA Conference 2003
13
Washer Size Selection
Improperly-sized washer
Raised portion of
terminal
Split lock
washer
Non-self locking nut
Steel washers
Correct
NBAA Conference 2003
Aluminum
terminal
14
Example: Terminal Stacking
A
NBAA Conference 2003
To prevent corrosion
from dissimilar metals,
put a cadmium washer
between aluminum and
copper terminals.
WF4
15