From Handbook of Electric Power Calculations, Third Edition


Determine the inductance of a transmission line having six identical round conductors (Fig. 9.2) arranged so that the currents on each side occupy the conductors equally with uniform current density.

Figure 9.2: Stranded-conductor transmission line.

Calculation Procedure

1. Calculate Flux of One Conductor

The flux linkages of conductor 1, which carries one-third of the current, can be deduced from the method established for the two-conductor line by: ? 1=( /2 ?) ( i/3) [1/4+ln( D 11'/ a)+ln( D 12 '/ a)+ln( D 13 '/ a) ln( D 12/ a) ln( D 13/ a)], where D 11? is the distance between conductors 1 and 1 ? and so on. When terms are collected, the equation becomes: ? 1=( i/2 ?) {ln[( D 11' D 12' D 13') 1/3/( r ?D 12 D 13) 1/3]} Wb turns/m. The flux linkages of the other two conductors carrying current in the same direction are found in a similar manner.

2. Calculate the Inductances

The inductances of conductors one, two, and three then become: L 1= ? 1/( i/3)=(3 2 10 7)[ln( D 11 ' D l2 ' D 13 ') 1/3/( r ?D l2 D 13) 1/3] H/m, L 2= ? 2/( i/3)=(3 2 10 7) [ln ( D 2l ' D 22' D 23') l/3/(

Products & Services
Bare Conductor Wire and Cable
Bare conductor wire and cable is made of conducting materials to carry electric current.
Flat Cables
Flat cables are used in computers for internal connections to peripherals. They consist of highly stranded, individually-insulated conductors that are laid parallel and then fused in a flat, flexible ribbon form. Flat cables are also referred to as ribbon cables.
Electrical Feedthroughs
Electrical feedthroughs transmit electrical current through the walls of a pressurized or vacuum system through a hermetic seal.
Single Phase Transformers
Single-phase transformers output single-phase AC power, typically while stepping-up or stepping-down the voltage between two circuits.
Electrical Power Wires
Electrical power wires are solid or stranded conductors surrounded by insulation, shielding, and a protective jacket. 

Topics of Interest

INDUCTANCE OF THREE-PHASE TRANSMISSION LINES Determine the inductance per phase for a three-phase transmission line consisting of single conductors arranged unsymmetrically (Fig. 9.3). Figure 9.3: A...

INDUCTANCE OF TWO-WIRE TRANSMISSION LINE Consider a transmission line consisting of two straight, round conductors (radius a meters), uniformly spaced D meters apart, where (Fig. 9.1). Calculate the...

INDUCTANCE OF SIX-CONDUCTOR LINE Calculate the per-phase inductance of the transmission line of Fig. 9.5 where the conductors are arranged in a double-circuit configuration. Figure 9.5: Line...

INDUCTANCE OF SINGLE TRANSMISSION LINE Using flux linkages, determine the self-inductance, L, of a single transmission line. Calculation Procedure 1. Select Appropriate Equation Use L= ?/ i, where...

INDUCTIVE REACTANCE OF BUNDLED TRANSMISSION LINE Calculate the inductive reactance per phase at 377 rad/s for the bundled transmission line whose conductors are arranged in a plane shown in Fig. 9.6.