JPS5920257B2 - power cable line - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electric cable line.

Metal sheathed single electrocardiogram cable lines generally use a cross-bond method to reduce the circulating current flowing through the sheath.

As shown in Figure 1, each phase cable IA, 1B, I
Two or more insulating connection foils 3 are provided for each section sandwiched between two grounded ordinary connection foils 2a and 2b provided for each metal sheath IAS, IBS, and IC8 of C, and insulating connection foils 3a, Before and after 3b, bonding wire 4
By connecting the metal sheath IAS, I
BS, cancels the circulating voltage induced in IC8, metal sheath IAS, IBS.

The current flowing through IC8 is suppressed.

However, in actual power transmission lines, it is difficult to make the spacing between each connecting foil and each cable the same due to topography and other reasons, and because the spacing between connecting foils is different, it is difficult to completely control the voltage induced in each metal sheath. I can't cancel it.

Therefore, the reality is that in some cases a fairly large current flows through the metal sheath, and the sheath losses are still quite large.

In order to suppress this sheath current, there is an idea of inserting a reactor in the middle of the cross bond wire, but when high frequency waves such as lightning surges and switching surges come, abnormally high voltage is generated in this part. Therefore, in order to suppress this, a new anti-corrosion layer protection device must be installed on both sides of the reactor, which is quite expensive.

The present invention has been made in view of such circumstances, and its purpose is to provide an electric cable that can significantly reduce the circulating current flowing through the metal sheath and that does not generate abnormal voltage even in the event of lightning surges. The purpose is to provide a railway line.

That is, the gist of the present invention is to use a paired cable for a metal sheathed cross bond wire, and to attach a reactor to the outer periphery of the cable for suppressing the sheath current.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be specifically described below with reference to the drawings showing one embodiment.

FIG. 2 shows an example of a cross bond, and the cross bond is one core wire (hereinafter referred to as 5 in this specification) of a pair of cables 5.5', 5//51.51'.

51〃 and the other core wire (referred to as B in this specification) 52.
This is done by connecting wires 52' and 52// as shown in FIG.

That is, one end of one cable sheath IAS is connected to the colored wire 52' of another paired cable 5' via the 9 wire 51 of the paired cable 5, and one end of the cable sheath IAS is connected via the colored wire 52 of the previous paired cable 5. The other end of the sheath IAS is connected to the 9th wire 51 of another third pair cable 5.

Each pair of cables 5, 5', 5// are connected to each other as described above, and each pair of cables 5, 5', 5// is connected to each other as described above.
A beam actuator is provided on the outer periphery of //, and an arrester 6 is connected to each of the nine wires.

Now, let's consider a case where a lightning surge hits a cable (for example, an IAS).

The equivalent circuit at this time is shown in FIG.

At this time, an induced voltage e is generated in the insulating connection foil, and currents are generated in the 9th wire 51 and the colored wire 52 of the paired cable 5 as surges in opposite directions.

This surge voltage is the sum of the voltage between the terminals of the arrester 6 and the voltage drop across the paired cable, but since the voltage between the arrester terminals is suppressed to the limited voltage and the surge impedance of the paired cable is small, it becomes a low value. The voltage induced in can be suppressed to a predetermined value or less.

Note that surge current flows through the paired cable, but since the direction of the surge current is opposite between the 9th wire and the colored wire, no magnetic flux is generated outside the paired cable, and the reactor 7 installed outside the paired cable.
will not work against such surges.

Next, consider the metal sheath current at commercial frequencies.

The metal sheath current can be expressed as the sum of the zero-sequence current and the circulating current, most of which is the latter, and in order to suppress the metal sheath current, it is sufficient to reduce this circulating current component.

The reason why a circulating current flows in an actual line even if a cross bond is provided is that the length of the section of the cross bond and the distance between the phases are different in each section, and an induced voltage Δe due to this deviation is generated in each cross bond circuit.

The induced voltage due to the shift of A, B, and C phases is △ea.

If △eb, △eb, the sum of these (△e
a+Δeb+Δec) becomes zero.

Here, the impedance of the cross bond circuit Zo,
If the inductor 2 of the reactor is L1 cross bond current Ia, Ib, Ic, then △ea=Zo-Ia+jwL(2Ia-Ib-Ic)△
e b=Zo −I b+jwL(2I b−I c−
Ia) Δe c=Zo −I c+jwL(2I c
-Ia-1b), and when these sums are taken, it is found that the sum of each current (Ia+Ib+Ic) is zero.

Considering this, the voltage drop △e in each phase is △e
= (Zo j 3wL) I, and the sheath electric current is the inductance L of the reactor.
It can be seen that it is limited by

In this embodiment, reactors 1 are provided for all three phases, but
The same effect can be obtained even if it is provided in only two of the three phases.

The reactor 7 may have one or more primary winding elements.

In this specification, the core wires of the paired cable are referred to as 9 wires and colored wires, but these names are given for convenience in order to explain the connection relationship, and do not have any special properties.

According to the present invention, the following effects are achieved.

(1) Since the sheath current can be suppressed by the reactor, sheath loss can be significantly reduced.

(2) Since the paired cable is used for the cross bond wire, the reactor (installed on the outer periphery of the paired cable) will not operate in response to a surge, so there is no need to install an arrester on the reactor.

(3) Since a pair cable is used for the cross bond wire, the voltage drop in this part can be ignored, and the surge voltage of the anticorrosion layer can be suppressed to about the arrester limit voltage.

(4) Generally, when the sheath current is suppressed using a reactor, etc., when a large current such as a ground current flows, a high voltage is generated between the reactors, so the reactor must be an expensive saturable type. In the circuit configuration, since the ground current is a zero-phase component, the reactor does not operate and no voltage is generated between the reactors, as in the case of a surge voltage.

Therefore, it is not necessary to make the reactor a saturable type, and it is inexpensive.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a conventional cross bond method, and FIG. 2 is an explanatory diagram showing an example of the present invention.
FIG. 3 is an explanatory diagram showing a portion of the equivalent circuit of the embodiment for surge voltage. 1 person: cable human phase, 1B two cable B phase, 1C: cable C phase, IAS: metal sheath A phase, 1BS: metal sheath B phase, 1cs: metal sheath C phase, 2a, 2b two-way connection foil, 3 : Insulating connection foil, 4 Nicross bond wire, 5.
5', 5'/: Against Kane. 9 wires of pair cable, 52
゜52', 52//: Pair cable color wire, 6: Arrester, 1: Reactor.

Claims (1)

[Claims] Two insulating connection foils are provided in each section sandwiched between two ordinary connection foils to be grounded in a 13-line metal sheath single electrocardiogram cable, and these metal sheaths are cross-bonded. In this electric cable line, the metal sheath on one side of the insulating connection foil 3 is connected to the colored wire 52' of the other paired cable 5' via the 9 wire 51 of the paired cable 5, and the metal sheath on the other side is connected to the colored wire 52' of the other paired cable 5'. The metal sheath is connected to the 9 wires 51 of the other pair cables 5 through the colored wires 52 of the former pair cable 5, and the 9 wires 51 of the three pair cables 5, 5', 5// ，
51'. 51 is connected to an arrester 6, and a reactor 1 is provided on the outer periphery of the paired cables 5, 5', 5//.