Electric Power Generation, Transmission, and Distribution

Travelers used in tension stringing must be free rolling and capable of withstanding high running or
static loads without damage. Proper maintenance is essential. Very high longitudinal tension loads can
develop on transmission structures if a traveler should ‘‘freeze’’ during tension stringing, possibly
causing conductor and=or structure damage. Significant levels of rotation resistance will also yield
tension differences between spans, resulting in incorrect sag.
Proper selection of travelers is important to assure that travelers operate correctly during tension
stringing and sagging. The sheave diameter and the groove radius must be matched to the conductor.
Figure 14.12 illustrates the minimum sheave diameter for typical stringing and sagging operations.
Larger diameter sheaves may be required where particularly severe installation conditions exist.

14.6.3 Sagging Procedure

It is important that the conductors be properly sagged at the correct stringing tension for the design
ruling span. A series of several spans, a line section, is usually sagged in one operation. To obtain the
correct sags and to insure the suspension insulators hang vertically, the horizontal tension in all spans
must be equal. Figures 14.13 through 14.18 depict typical parabolic methods and computations required

Conductor in Travelers

Sag Correction

(Typ.)

See Detail A For Vector Diagram

Of Conductor Tension At Traveler

See Detail B For Vector Diagram

Of Conductor Tension At

Suspension Clamp

Conductor in

Suspension Clamps

“Deadend”
Snub Structure
(“Zero” Clipping Offset)

“Suspension”

Snub Structure

(“Zero” Clipping Offset)

Suspension

Suspension

Plump

Mark

Plump

Mark

Clipping

Offset

Clipping

Offset

Suspension

Suspension

Detail A Detail B Guys

H 3 H 0 H 0

H 5

H 0

H 0

H 4

Y 2

Y 1

H 1

H 0

H 2

H 3

H 0

(Y 2 −Y 1 )

H 0

V^1 V^1 V

1

V

T

T^1

V^1

V

T

VV

H 4

H 3 = H 4 + W (Y 2 − Y 1 )

Stringing Tensions T Are Equal

Horizontal Tensions H 0 Are Equal

Sagging Tensions T & T^1 Are Unequal

NOTE:

W = Conductor Wt

Per Unit Length

VECTOR DIAGRAM

FIGURE 14.13 Clipping offset illustration.