Electric Power Generation, Transmission, and Distribution

Provision for conductor splicing during stringing must be made at tension site or midspan sites to avoid
pulling splices through the travelers.
During the stringing operation, it is necessary to use proper tools to grip the strands of the conductor
evenly to avoid damaging the outer layer of wires. Two basic types or categories of grips are normally
used in transmission construction. The first is a type of grip referred to as a pocketbook, suitcase, bolted,
etc., that hinges to completely surround the conductor and incorporates a bail for attaching to the
pulling line. The second type is similar to a Chinese finger grip and is often referred to as a basket or
‘‘Kellem’’ grip. Such a grip, shown in Fig. 14.11, is often used because of its flexibility and small size,
making it easily pulled through sheaves during the stringing operation. Whatever type of gripping device
is used, a swivel should be installed between the pulling grip and pulling line or running board to allow
free rotation of both the conductor and the pulling line.
A traveler consists of a sheave or pulley wheel enclosed in a frame to allow it to be suspended from
structures or insulator strings. The frame must have some type of latching mechanism to allow insertion
and removal of the conductor during the stringing operation. Travelers are designed for a maximum safe
working load. Always ensure that this safe working load will not be exceeded during the stringing
operation. Sheaves are often lined with neoprene or urethane materials to prevent scratching of conduct-
ors in high-voltage applications; however, unlined sheaves are also available for special applications.

FIGURE 14.11 Basket grip pulling device.

100 40

75 30 1.4 3.5

1.2 3

1.0 2.5

0.8 2

0.6 1.5

0.4 1

50 20

25 10

15

1.0

2.5

1.5

3.75

Conductor Diameter (Dc)

2.0

Sheave Diameter

Groove Radius

5

2.5 (inches)

(cm)

(inches)(cm)

(cm)(inches)

Minimum Sheave Diameter (D

) at Base of Grooves

Minimum Radius (R

) at Base of Grooveg

6.25

25

35

Rg, 1 or 2 Layer

Rg, 3 Layer

Min. Rg

Rg, 4 Layer

FIGURE 14.12 Recommended minimum sheave dimensions.