CZ149699A3 - Inductor - Google Patents

Abstract

This invention provides an inductor including an elongate conductor bar (10) of rectangular cross section, at least part of the bar being surrounded by a sleeve (20) which provides substantially no electrical conduction path through the sleeve in a direction away from the conductor bar. Such a sleeve (20) concentrates the lines of magnetic flux in the sleeve. The advantage of such an inductor is that at higher frequencies (e.g. above 100 Hz) the effect of the "skin effect" is reduced whilst at lower frequencies but high currents the stress on the inductor is also reduced.

Description

Title of the invention:

Inductor

Annotation:

The inductor comprises an elongated conductive rod (10) of rectangular cross section, at least a portion of the conductive rod (10) being surrounded by a sleeve (20) that provides substantially no electrically conductive path through the sleeve (20) away from the conductive rod (10). The sleeve (20) concentrates the magnetic flux lines in the sleeve (20). The advantage of this inductor is that at higher frequencies (e.g., above 100 Hz) the effect of the skin effect is limited /, while at lower frequencies but at high currents, the mechanical voltage of the inductor is also reduced.

(13) Type of document: A3 (51) Int. Cl. ⁶ :

H 01 F 17/06 H 01 F 37/00

And ^{of the} W Inductor

Technical field

The present invention relates to an inductor and to a process for its manufacture. More specifically, the present invention relates to an inductor that is suitable for transmitting relatively large currents (e.g., tens, hundreds or even thousands of amperes).

BACKGROUND OF THE INVENTION

Such inductors may be required for use with power distribution and / or transmission networks (generally referred to herein as power networks). In particular, such inductors are needed in the filter unit (transfer property maintenance unit) described in co-pending published international patent applications of the same applicant: PCT / GB95 / 00893, PCT / GB95 / 00894 and PCT / GB95 / 02023. The descriptions and explanations given in these three patent applications are to be mentioned in connection with the present invention and are hereby incorporated by reference into this description.

Previously, conventional spiral wound inductors (i.e., inductors including wire wound around a core) were manufactured. However, in the manufacture of high-frequency filter elements using an inductor of this type, which elements are required to transmit relatively large currents at very low frequencies (e.g., 50 to Hz, such as in electrical power networks), conventional spiral wound inductors are limited by their physical dimensions . The greater the required inductance and / or the higher the load current, the greater the physical size of the inductor.

♦ Β

In addition, inductive elements of the type required in transmission condition maintenance units may have to withstand hundreds or even thousands of load and / or fault current amperes. These elements should also maintain a relatively low impedance at very low frequencies (i.e. below

100 Hz), while at high frequencies they should still maintain the ideal inductor property, i.e. the reactance is directly proportional to the applied frequency for a fixed inductor value.

Spiral wound inductors suffer from extremely high mechanical stresses when transmitting relatively large load and / or fault currents. In addition, conventional spiral wound inductors are limited in their high frequency power due to capacitance between threads, i.e. 15 capacitance of each thread relative to the following. Heat loss and power losses (commonly referred to as I ² R losses) are also a major problem with this type of component. For this reason, spiral wound inductors are not desirable for this purpose.

It is an object of the present invention to provide an inductor that reduces some or all of the above-mentioned problems.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention provides an inductor comprising an elongated conductive rod of rectangular cross section, at least a portion of which is surrounded by a sleeve that provides substantially no electrically conductive path through the sleeve in (or in any or all) direction from the conductive rod.

• · · · · ** φ · ··

By virtually no electrically conductive path, it is meant that for practical purposes there is minimal electrical conductivity, i.e., insufficient (and preferably none) to be practically significant. Such a sleeve concentrates the magnetic flux lines in the sleeve. The advantage of such an inductor is that at higher frequencies (e.g., above 100 Hz) the skin effect is reduced, and at lower frequencies but high currents the conductor stress is also reduced. These advantages will be explained in more detail below.

Preferably, the sleeve is elongate and preferably has a hollow rectangular cross-section, although it may have other cross-sectional shapes, for example circular, square, multifaceted, and the like.

Preferably, the sleeve closes the conductor and preferably lies close to or touches all sides of the conductive bar.

Alternatively or additionally, the sleeve may surround more than one conductive rod, for example two, three or optionally more conductive rods, each conductive rod being isolated from the other. The conductive rod may comprise one or more conductive elements, for example it may be made of fixed conductors.

Preferably, the conductive rod has a minimum cross-sectional area

4.5 mm, particularly preferably 10 mm ² . Advantageously, the inductor can transmit a current of at least 10 A without undue thermal effects.

Preferably, the sleeve is made of, for example, a ferromagnetic material or the like, such as a sintered or layered material, which is either a semiconductor conductor or an insulator, so that there is no low impedance path inside the sleeve. For example, laminated iron, laminated brass or nickel, or sintered ferrite could be used.

There should be minimal or substantially no electrical conductivity between the conductive rod and the sleeve. If the sleeve is of insulating material, then nothing else may be required. However, if the sleeve is of a conductive material or a semiconductor material, an insulating layer may be incorporated between the sleeve and the conductive rod, although this may not be necessary depending on the materials used.

If the sleeve is made of a laminated conductor, then the layering may be such as to provide high impedance inside the sleeve.

Preferably, the inductor comprises means for connecting it to other electrical components. Such means may be, for example, connecting plates, couplings or terminals connected to the conductive rod.

In another aspect, the present invention provides a method of manufacturing an inductor, comprising the step of closing a rectangular conductive bar with a sleeve that provides substantially no electrically conductive path through the sleeve in a direction away from the conductive bar.

In another aspect, suitable high-frequency inductive reactance values for certain parts of electrical equipment, such as cables, meters, substations or transformer outlets, can be achieved according to the present invention by fitting a suitable sleeve over existing wire sections. Such conductor sections may have any cross-section or shape, for example circular, square or triangular. However, as in the foregoing, a preferred solution will be for a rectangular section of the conductive element to be closed by a suitable sleeve, for example rectangular.

Thus, suitable sockets around the minor network cable may also be incorporated into the electrical network, for example, at the point where the minor cable connects to the main cable. This prevents the high-frequency signals from moving along the side cable from the main cable and thus can change the network response characteristics of the network when needed.

The present invention also provides a communication apparatus (referred to herein as a transmission condition maintenance unit) for use with a power grid that is used for both high-frequency telecommunications signals and low-frequency power signals.

The transmission condition maintenance unit includes a low pass filter portion or portions to filter out a high amplitude low frequency power signal, i.e., to separate it from the telecommunications signals and to allow it to pass through the transmission condition maintenance unit. The unit also includes a high-pass coupler for inputting and receiving telecommunication signals from the network, and, preferably, a termination element with a similar impedance to that of the network at that location. The low-pass portion comprises an inductor according to any of the preceding aspects of the present invention.

The use of such a unit (as described in the three previously published PCT patent applications of the same applicant as mentioned above) ensures that (e.g., high frequency) telecommunications signals do not carry internal low voltage lines present inside buildings and / or noise sources from low voltage lines inside buildings, they shall not clog or damage radio frequency telecommunications signals that are transmitted to the external power network.

The filter element (filter) according to the present invention, which aims to reduce telecommunications signals entering the internal network of user buildings, preferably has no more than 1 volt gradient on top of it even though it transmits a 100 amp θ load current from, for example, a 240 V single phase source.

Hz.

Preferably, the network condition maintenance unit provides impedance matching between the receiving and transmitting devices and the power network. Additionally, the network condition maintenance unit can transmit full load current at power frequencies (e.g., 50 Hz or 60 Hz) while still transmitting telecommunications signals (e.g., voice and data signals), and can also safely transmit an error current to the power frequency. : 0 size and duration will be determined by the design parameters of the network.

The network transmission unit maintenance unit preferably comprises a low-pass filter comprising a main inductor 5 according to one aspect of the present invention, arranged between the input of the mains and the output of the mains and connected at each end to an input / output signal line arranged parallel to the input. The two connections include a first capacitor and a second capacitor, each of a predetermined capacitance depending on the portion of the frequency spectrum to be used for communication purposes.

In this arrangement, the main inductor operates to prevent communication signals from the I / O signal line 5 from entering industrial buildings or common houses. The inductor has a value that will present a relatively high impedance at the respective frequencies. Therefore, this inductor has a high inductance, such as 10 μΗ to 200 μΗ, for frequencies of 1 MHz and above.

¹⁰

The first capacitor that connects the power input and the signal input / output line acts as a coupling capacitor to allow communication signals to pass from the signal input / output line while attenuating all low frequency components to or around frequency 15 of the power grid (i.e., 50 or 60 Hz) ).

A second capacitor, arranged between the power outlet and the ground, provides further attenuation of the communication signals.

To treat a possible failure of either of the first and second capacitors, each such capacitor is preferably provided with a corresponding fuse arranged between the first and second capacitors and the signal input / output line. In addition, additional safety measures may be incorporated by providing an additional inductor (s) (which may be formed according to the present invention) arranged between the connections between the signal input / output line and the first and second capacitors. This inductor has no effect on communication frequency signals _and IE will provide a path to ground if the first capacitor • · creates error, thereby allowing the first fuse to break without allowing the power frequency signal onto the signal input / output line.

The inductance of the main inductor depends on its design. The 10 pH inductance mentioned above is preferably minimal (although an inductance of even low to 1 or 2 μΗ may be assumed), and with a suitable inductor a higher inductance can be achieved, for example of the order of 200 μ dosaženo. Alternatively, a plurality of ^1-0 inductors coupled in series could be used.

The coupling capacitor preferably has a capacity ranging from

0.01 to 0.50 pF and the second capacitor, connecting the power outlet to the signal input / output line and ground, preferably has a capacity ranging from 0.001 to 0.50 pF.

The second inductor disposed on the signal input / output line preferably has a minimum inductance of about 250 pH. This inductor therefore has minimal or no effect on high frequency communication signals,

2q which are present on the signal input / output line.

The conductor used to construct an inductor with an inductance of 250 pH should have a sufficient cross-sectional area to transmit the fault current, as determined by the series breaker connection, should the decoupling capacitor fail to short-circuit in the event of failure.

Preferably, the occurrence of parasitic or intrinsic resonances in the inductive or capacitive elements is avoided. Since the lower cut-off frequency of the transmission condition maintenance unit is increased, the minimum values of inductance and capacitance can be reduced proportionally.

...

* *

In a preferred embodiment of the invention, the filter is assembled in a shielded box so as to provide good ground and to prevent the emission of communication signals.

In a further aspect, the present invention proposes an electrical distribution and / or power transmission network (which may be a long distance and branched multipoint), at least a portion of which may be outside the building, the network comprising input means for inputting telecommunication signals, e.g. more than about 1 MHz, per ¹⁰ phase conductor of the network and output means for extracting said telecommunications signals from the network, said signals are preferably portable along said outer part of the network, the network including as part of either the input or output means (or both) the communication apparatus includes a low-pass section to allow low-frequency mains electrical power signals of high amplitude to pass through the network (e.g., into a building) and preferably to prevent (e.g., high-frequency) electrical noise (e.g., from a building) at the entrance to the network (and preferably to a section)

And a coupling element for input and / or removal of telecommunications signals from the network, said low-pass filter comprising a main inductor or inductors according to one aspect of the present invention, arranged between the mains input and the mains output.

--2 5

Preferably, the network connects a plurality of separate buildings and said signals are portable between these buildings. Preferably, the signal is propagated between the line conductor (s) of the network and ground or zero, although this signal propagation can be realized between the phase conductors.

and

Preferably, the network comprises more than one (for example, three) phase conductor, said input means being for input of telecommunication signals to one or more of said phase conductors and said output means being for receiving telecommunication signals from at least one other phase conductor. Preferably, the input means is for inputting a signal to only one of the phase conductors. Preferably, the carrier frequency is between about 1 to 60 MHz.

Preferably, the coupler is suitable for use with a θ telecommunications signal having a carrier frequency greater than

MHz. Preferably, the communication apparatus comprises a termination element for terminating the apparatus with a similar impedance to that of the network at that location.

Preferably, the inductor is coupled at the input end of the electrical network to the first capacitor and at the output end of the electrical network to the second capacitor, wherein said first capacitor connects the electrical input to the signal input / output line and said second capacitor connects the electrical output to ground.

In another aspect, the present invention provides a signal transmission method comprising inputting telecommunication signals, e.g. having a carrier frequency greater than about 1 MHz, to a phase conductor (e.g., long-distance and branched multipoint) electrical power distribution and / or transmission network of which at least a part may be outside. building, and subsequently receiving said signals, said signals being transmitted over said outer portion of the network, said signals being fed to and / or received from the network using _; q of a communication apparatus, the communication apparatus comprising a low-pass portion comprising an inductor according to one

An aspect of the present invention to allow low-frequency mains electrical power signals of high amplitude to pass through a communication apparatus (e.g., from the network to the consumer building and to prevent electrical noise from the building at the 5 input to the network), and a coupler for input and / or removal of the telecommunications signal from the network.

Preferably, the communication device conducts telecommunications signals to the network from the consumer building.

In another aspect, the present invention provides an LO inductor comprising an elongate conductive rod, at least a portion of said rod being surrounded by a sleeve that provides substantially no electrically conductive path through the sleeve in a direction away from the conductive rod, the inductor having an inductance of at least 1 μΗ, preferably 5 μΗ more preferably 10 μΗ, particularly preferably 15 μΗ or 100 μΗ and optionally at least 250 μΗ or 500 μΗ or 1 mH. The present invention also contemplates a corresponding method of manufacturing such an inductor.

Exemplary embodiments of the present invention will be described in more detail in the following description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 schematically illustrates an inductor according to the first aspect of the present invention;

Fig. 2 schematically shows a conductor of circular cross-section;

Fig. 3 schematically shows a ribbon conductor with a rectangular cross-section;

• »

Giant. 4 schematically illustrates a connection of two cables according to one aspect of the present invention;

Fig. 5 shows a spare electrical diagram 5 of a coupler according to one aspect of the present invention;

Fig. 6 schematically illustrates an inductor according to another aspect of the present invention;

Fig. 7 shows a replacement electrical diagram of a first embodiment of a network transmission unit maintenance unit for use with the present invention;

Giant. 8 is a plan view of the network condition maintenance unit of FIG. 12;

Fig. 9 is a view of a circuit board for the network condition maintenance unit of Fig. 8;

Fig. 10 shows a block diagram of a network traffic condition maintenance unit according to an aspect of the present invention;

Fig. 11a shows a block diagram of a network condition maintenance unit in use with the present invention;

Fig. 11b shows a block diagram of a network condition maintenance unit in use with the present invention;

Fig. 12 shows a block diagram of a second embodiment of a network condition maintenance unit for use with the present invention;

Fig. 13 shows another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Giant. 1 depicts one embodiment of an inductor according to an aspect of the present invention. The inductor comprises a conductive rod 10 surrounded by a housing 20. The conductive rod 10 has a width

W and thickness T.

The advantages provided by the inductor geometry of FIG. 1 will be better understood in conjunction with the analysis given below for the conductors shown in FIGS. 2 and 3. FIG. 2 shows a cylindrical conductor of length L and diameter D, while FIG. 3 shows a generally rectangular conductor of length L with width W and thickness T.

For round conductor with length L and diameter D:

Cross sectional area (CSA) = mD conductors ^2/4

Wire circuit = tcD

Wire surface area (SA) = πϋ x L where: π = 3,142

D = conductor diameter 25 ^y

L ~ conductor length

For D = 1 unit is: CSA = π / 4 square units or (7π / 4) ² units perimeter = π

SA = 7 µL

·. *

For a rectangular ribbon wire with a width W, a thickness T and a length L:

Conductor cross-sectional area (CSA) = W x T

Wire Circuit = 2 [W + T]. 5

Wire Surface Area (SA) = 2L [W + T]

For a rectangular ribbon wire with CSA = π / 4 square units, W x T = π / 4 and 2 [W + T] = rod circumference.

The perimeter is minimal when W = T, ie the bar has a square cross section and the perimeter - 4W = 4T and W ^: = π / 4

Thus, the circumference of the bar = 4 x (^ π) / 2 = 2 (7π) which is greater than π.

Thus, the perimeter of the square bar is larger than the perimeter of the circular bar for a fixed CSA.

Then generally for a constant CSA, when W -> oo, T -> 0 or when T -> <x>, ty} -> 0. Therefore, 2 [W + T] is always greater than π.

This implies that the circumference of the rectangular bar is always 5 greater than the circumference of the circular bar for the same CSA.

Accordingly, it further follows that for a given CSA round conductor, a rectangular conductor with the same CSA will have a larger circumference that approaches infinity when its thickness becomes very small.

• «

Still further, it follows that when the aforementioned conductors have a length of L units, the surface area of the rectangular strip conductor will also approach infinity when its thickness becomes very small.

These dimensional relationships between round and rectangular conductors are of great importance in conductor structures since the following properties apply:

At extremely low frequencies (DC (0 Hz) to approximately 100 Hz), electrical currents spread almost evenly over CSA conductors.

At higher frequencies (above 100 Hz), electrical currents tend to shift toward the outer surfaces of the conductor. This phenomenon is known as wire skin effect. The changes caused by the skin effect will be smaller in the rectangular wire type when compared to a circular wire with the same CSA. Thus, a rectangular conductor made of the same material and with the same CSA will have a much increased transmission capability for high-frequency currents.

3.

As electrical currents are routed through the conductor, the resistance of the conductor causes heat to build up inside the conductor, which in fact limits the maximum current the conductor can carry. For any given CSA conductor, a rectangular conductor can be constructed such that the thickness-to-width ratio provides a much larger surface area and therefore a greater cooling ability than a circular conductor with the same

CSA.

ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft

For all these reasons, using a rectangular conductor is a significant improvement over using a circular conductor.

The inductance of the wire coil can be increased by forming a coil around the core of a suitable material with which the magnetic flux lines concentrate. For example, iron, brass and various types of ferrite can be used as core material. The conductor may also be provided with a sleeve of these types of materials, i.e. completely or

LO partially surrounded by a sleeve.

If a rectangular conductor type is provided with a ferrite, say, ferrite as shown in Fig. 1, its inductive reactance will be greatly increased at high frequencies and yet will have little or no change at 15 extremely low frequencies, i.e., at DC current. (0 Hz) up to about 100 Hz.

Therefore, when such rectangular inductors fitted with a sleeve are incorporated into high, low and band pass filter structures (such as those used in the design of HFCPN routing couplers) of high-pass tuned networks, loss-related problems can be reduced or even eliminated

I ² R (heat loss of conductor) and problems associated with relatively large physical dimensions of inductors.

At extremely low frequencies, that is to say say 100 Hz (electricity grids usually have a frequency of 50 or 60 Hz and can also be direct current, i.e. 4 944 94 44 44 44 94

Hz), the ferrite sleeve has only a negligible effect on the performance of the rectangular wire. However, at frequencies above 1 MHz, this sleeve has the aforementioned effect, providing a relatively high value of inductive reactance, and generates high attenuation of high frequency signals when coupled to a suitable decoupling capacitance.

Conventional inductors suffer from a problem at high frequencies due to their inter-threaded capacitance, i.e., the capacitance of each thread relative to the next thread. By utilizing the inductive reactance of the rectangular type inductor provided with the sleeve, this effect of the inter-threaded capacitive impedance is minimized. The inductive material of the sleeve may be coated on the conductor through an insulating membrane, if desired, or it may be embedded in a suitable adhesive resin compound and formed over the conductor.

Heat dissipation can also be improved in this way, and the sleeve-fitting technique can be incorporated into power cable connections to form high-frequency directional couplers within the junction box 400, as illustrated in Fig. 4, for connecting two multi-phase cables 40, 410. . 5 illustrates a substitute electrical circuit diagram having a directional coupling effect at high frequencies.

The optimum coupling is from the multi-phase cable 402 to / from the single-phase cable 404 via the coupling 406 with minimal coupling to the cable 40 due to a series of inductors L ₁₀ , L ₂₀ , L ₃₀ formed by ferrite sleeves 408 as shown in Fig. 4 The phase conductors of the cables may have any cross-section, for example circular, wedge-shaped, square or rectangular, and are provided with ferrite sleeves either on each conductor or formed over the conductors in a cluster. These conductors may have rectangular cross-sections formed in the sleeves to provide optimum performance as previously described.

The inductive components so provided with the sleeves may be incorporated into the mains connections as shown in Figure 4 (and as schematically shown in Figure 5), or may be mounted inside equipment such as transformers and junction boxes in enclosures. electricity meters or electrical equipment. In fact, the current meters of the meters can be provided with sleeves so that their reactance increases with frequency, and can form part of an integral filter or a high-frequency directional coupler or HFCPN unit for maintaining transmission conditions.

Similarly, the fuse elements may be provided with sleeves and have elements formed from rectangular cross-section wires so that their inductive reactance can increase with frequency and form part of a directional coupler or HFCPN unit for the maintenance of transmission conditions.

It could happen that sufficient inductive reactance values could be obtained at high frequencies in certain elements of electrical equipment, such as meter cables, substations and transformer terminals, by fitting appropriate ferrite sleeves over existing wire sections (cross-sectional, e.g. , circular, elliptical, multilateral, rectangular, square, triangular, etc.). This is illustrated in FIG. 6. A preferred solution is for a rectangular cross-section with a similar surface area to be suitably provided with a ferrite sleeve or other similar material.

Giant. 13 depicts a three-core cable 1300 around which the sleeve 1320 of the present invention is mounted

5 of the invention to form an inductive element. The sleeves could, of course, be retrofitted to an already installed conductor cable and not all of the wires must be fitted with sleeves. Moreover, the cable could of course contain more or less conductors.

¹⁰

The cable 1300 includes an outer cable sheath 1330 within which there is a zero ground sheath 1340. Three conductors 1310 are surrounded by a layer of insulating filler 1350 that separates the wires 1310 from the zero ground sheath 1340. Each of the wires

1310 is coated with a respective separate insulating sheath 1360 15 and all three conductors are surrounded by one sleeve 1320 according to the present invention.

The sleeve 1320 contains an amount of ferromagnetic material that is selected to be proportional to the vector

20 of the sum of 50 or 60 Hz current in the multi-phase wires 1310. The material properties affect the amounts used or required. The sleeve 1320 may be split to allow for ease of insertion (i.e., to avoid wiring breaks) and may be held in place by a non-metallic clamp or P-clip 1370. The value of the inductances generated through this arrangement will depend on the type or quality of the used ferromagnetic material, its overall length and its proximity to the conductors. The greater the thickness of the ferromagnetic sleeve, the less likely it will be saturated as a result of the vector sum of the multiphase current in the conductors at a frequency of 50 or 60 Hz.

A suitable sheath material could be Neosid MMG ferritite class F9C. For a sleeve having dimensions, for example, an outer diameter of 63 mm, an inner diameter of 38 mm and a thickness of 25 mm, the magnitude of the vector sum of the current flowing in one direction through the ferrite is approximately 25 amps when saturation begins to occur. The saturation current can be increased by fitting a thicker sleeve with the same inner diameter. In this example, this arrangement produces an inductance of 11 μΗ per 25 mm length. The inductance can be increased by increasing the length of the ferrite sleeve and this increase is linear, i.e., 50 mm in length providing an inductance of 22 μΗ and the like.

The basic elements of the network condition maintenance unit 1104 according to one aspect of the present invention are illustrated in Figures 11a and 11b. Giant. 11a shows a transmission condition maintenance unit 1104 (also shown in FIG. 10 as a transmission condition maintenance unit 1000). The transmission condition maintenance unit may be considered equivalent to the low pass filter 1100 and the coupling capacitance element 1102 (which may be considered the high pass filter element).

The low-pass element 1100 allows the network power to be supplied from the distribution network to the consumer, while preventing the high-frequency communication signals from entering the consumer's building. The coupling capacitance element 1102, or the high pass filter element, is configured to connect the high-frequency communication signals to the utility network while preventing network power from entering the communication apparatus.

• a • *

0 «• 0 0 · 0 ·

0,000 «00

The components of the transmission condition maintenance unit may be mounted in, for example, an electricity meter housing located in a consumer building, or alternatively may be incorporated into a compartment at the rear of such a meter.

.5 Alternatively, the necessary components may be placed in, for example, a high breaking capacity fuse (HRC) or a fuse unit in the consumer building.

In Fig. 12, one embodiment of a transmission condition maintenance unit (which is essentially a filter or a filter) according to one aspect of the present invention is generally referred to as a transmission condition maintenance filter 120 and is connected between the power input 1202 and the power output 1204. The signal input / output line 1206 is also connected to the filter. The power line is a standard line

5 a 50 Hz or 60 Hz power supply that provides a 110 V or 240 V household power supply at a maximum current of 100 amps for normal use.

Filter 1200 may be placed in a shielded box that prevents the transmission of communication signals to external devices and which provides a 1208 ground connection for the signal input / output line 1206. Filter 1200 includes a first or main inductor 1210 according to one aspect of the present invention. This provides an inductance of approximately

5 μΗ. This may be the minimum value to use the signal characteristic, or an inductor with an inductance of 10 μΗ or less may be sufficient. The use of different materials or a number of inductors connected in series can increase the inductor's inductance up to, for example, approximately 200 μΗ.

ΦΦ · φ φ · · φ β β φ φ φ φ φ φ φ • · · · • • • φ φ φ · · · · · · · φ φ φ φ φ φ φ Φ φφ · Φ φφ

The end of the main inductor 1210 is provided with a signal input / output line 1206. The first connection 1212 between the power input 1202 and the signal input / output line 1206 comprises a first or coupling capacitor 1214 having a capacity of between 0.01 and

0.50 pF and preferably about 0.1 pF. This coupling capacitor 1214 is coupled to the first fuse 1216, which is arranged here to burn in the event of a failure or error that would occur in the capacitor 1214.

The second connection 1218 includes a second capacitor 1220 having a capacity of between 0.01 and 0.50 pF and preferably about 0.1 pF. This capacitor 1220 provides further attenuation of the communication signals by dropping them to ground 1208. The second fuse 1222 is used here for blowing when an error occurs in this Ί 5 of the second capacitor 1220, thereby preventing further damage to the unit.

The signal input / output line 1206 is coupled to a second inductor 1224, which may be constructed according to the present invention, and having an inductance of about 250 pH at least. This second inductor 1224 is designed to reduce damage in the event of a coupling capacitor 1204. In the event of such a failure, the second inductor 1224 provides a path to ground 1208 for a 50 Hz mains power, thus blowing fuse 1216. This second inductor 1224 has no effect the communication frequency signals that occur on the signal input / output line 1206.

Giant. 7 illustrates a replacement electrical circuit diagram 30 of a second filter embodiment according to an aspect of the present invention. The filter 700 comprises a pair of inductors L1, L2.

4

4 4 4 4 4 4 444 4 44 44 4 4 4 444 44

4 * «· 3 · ·

4444 44 44 · 4 44 44 (which can be constructed according to the present invention), which are arranged in series between the power inlet 720 and the power outlet 740. The preferred value of inductance for inductors L1 and L2 is approximately 16 μΗ. The inductors L1 and L2 may have different values to limit the harmonic response relationships.

A first fuse F1 and a capacitor C1 are connected between the high-frequency input line 760 and the power input 720, and a third inductor L3 (which can also be constructed according to the present invention), which acts as a high-frequency choke and has usually an inductance value of 250 μΗ.

Similarly, a second fuse F2 and a second capacitor C'2 are connected between the coupling point of the inductors L1 and L2 and the ground. A third fuse F3 and a third capacitor C3 are connected between the power outlet 740 and the ground. A typical value for capacitors is around 0.1 pF and for fuses approximately 5 amperes HRC (high breaking capacity).

The values given for these components are exemplary only, and other preferred values will be appropriate for other designs with different frequency and power network parameters.

FIG. 8 shows a typical housing arrangement for a network transmission unit maintenance unit according to an embodiment of the present invention. The main inductors L1 and L2 are placed in a shielded box 820. The inductors L1 and L2 are shown as coil inductors, but could be replaced by inductors according to the present invention. The illustration shows the various connections, including the communication interface port 800, to which the user's communication device should normally be connected. However, as shown in FIG. 8, this communication interface port 800 may be terminated by a terminal 810 for impedance matching of this port.

- c

Giant. 9 shows a circuit board 96 that fits inside the shielded box 82Q of FIG. 8 and on which the remaining circuit components for the network condition maintenance unit of FIG. 7 are located. Connections A, B, C, D and E are shown. connecting the appropriate points of the shield box 820 shown in FIG. 8.

Giant. 10 is a schematic block diagram of a network transmission condition maintenance unit 100 illustrating various building blocks 1005, 1010, 1020, 1030, 1040, 1050, and 1060 of a network transmission condition maintenance unit 1000. To design a suitable unit for maintaining network transmission conditions, the circuits represented by blocks 1010 and 1060 should be high impedance elements in the spectrum of desired communication frequencies (e.g., 1 MHz and above) and low impedance elements at mains frequency (i.e., 50 or 60). Hz), that is, these elements are inductors. Similarly, blocks 1005 and 1020 should be low impedance coupling elements in the spectrum of desired communication frequencies and separating high impedance elements at the mains power supply frequency, i.e., these elements are capacitors.

Interruptible safety couplings 1040 and 1050 with high tripping power for limiting the fault current are connected in series with blocks 1005 and 1020. For connection to the communication tq port, an additional impedance matching circuit 1030 may be included. This element may be external to the unit 100 to adapt the network transmission conditions.

The optimal values of blocks 1010, 1005, 1020 and 1060 will depend on factors including:

(a) the required frequency range over which the network is to be adapted.

(b) the unit length of the net to be adapted accordingly.

(c) the number and types of loads that can be expected on this network.

d) the characteristic impedance of the line phase conductors relative to each other and / or to the ground (as appropriate), i.e., the outer electrical sheath of the conductors.

(e) the impedance of communication interconnectors.

Similarly, blocks 1010 and 1060 may include a plurality of individual inductors connected in series and, if no wiring is required, for example, on street light lamps, blocks 1040, 1005, 1030, and 1060 may be omitted.

The blocks 1005 and 1020 may include a plurality of capacitors in series and / or parallel configuration depending on the respective operating voltages, i.e., 240 V, 415 V, 11 kV, 33 kV, and the like.

Alternatively, or additionally, items 80 and 82 may include two or more capacitors connected in parallel to overcome, for example, deviations in the capacitor design when adapting the network over a relatively wide frequency range, for example from 50 MHz to 500 MHz.

In addition, blocks 1010, 1050 and 10QQ of the network condition maintenance unit 1000 may be connected to the network

E.

cascades, if desired. In a typical design, the greater the number of cascade elements involved, the sharper the instantaneous response of the filter, and the greater its attenuation due to resonance prevention and the like.

The above embodiments of the present invention have been described by way of example only, and various alternative features and modifications with respect to what has been specifically described and illustrated can be made entirely within the scope of the present invention, as will be readily appreciated by those skilled in the art.

Claims (26)

PATENT CLAIMS An inductor comprising a plurality of elongate conductive bars, at least a portion of which is surrounded by a single ferromagnetic sleeve that provides substantially no electrically conductive path through the sleeve in the direction of the conductive bars, each of the conductive bars being insulated from others. Inductor according to claim 1, characterized in that it has an inductance of at least 1 μΗ. An inductor according to claim 1 or 2, characterized in that the sleeve is elongated and has a hollow rectangular cross section. Inductor according to any one of the preceding claims, characterized in that the sleeve closes the conductor and lies in close proximity to or touches all sides of the conductive rod. An inductor according to any one of the preceding claims, characterized in that each of the conductive bars is a different phase conductor with respect to the other bars. Inductor according to any one of the preceding claims, characterized in that the conductive rod has a minimum cross-sectional area of 4.5 mmu Inductor according to any one of the preceding claims, characterized in that it can conduct a current of at least 10 A. K% - « ^c ·· * · ·· · * * · An inductor according to any one of claims 1 to 11 7, characterized in that the conductive bars are all of rectangular cross-section. Inductor according to any one of the preceding claims, characterized in that the sleeve is made of conductive or semiconductive material. An inductor according to any one of the preceding claims, characterized in that an insulating layer is incorporated between the sleeve and the conductive rod (s). A communication apparatus for use with a power supply network that is used to transmit both high-frequency telecommunications signals and low-frequency network power signals, the apparatus comprising a low-pass portion for filtering out high-frequency signals and allowing high-frequency low-frequency network power signals to pass through through the apparatus, and wherein the apparatus also includes a high-pass coupler for inputting or withdrawing telecommunications signals from the network, characterized in that the bottom portion the leakage comprises an inductor according to any one of of the preceding claims. 25 12. Communication device according to claim 11 s e by the inductor is arranged between the power input and the power output and at one end thereof is connected to the signal input / output line. * 000 · · · · 0 · 0 * 0 0 0 * 00 · 0 0 «0 0 0 0 0 0 0 0 0 0 0 13. A power distribution and / or power transmission network, said network comprising input means for inputting telecommunication signals onto a phase conductor of said network and output means for removing said telecommunication signals from said network, characterized in that said network comprises as part either input means, or output means, or both, a communication apparatus according to claim 10 or claim 11 for enabling a low frequency mains electrical power 10 of a large amplitude signal to pass along the network and to input and / or remove telecommunications signals from the network. 14. The network of claim 13, which connects a plurality of separate buildings and said signals are transferable between the buildings. 15. A network as claimed in claim 13 or 14, characterized in that it comprises more than one phase conductor, said input means being for input of telecommunication signals to one or more of said phase conductors. 20o of the phase conductors and said output means are for taking these telecommunication signals from at least one other phase conductor. The network of claim 13, 14 or 15, wherein the communication device is suitable for use 25 _{having a} telecommunications signal having a carrier frequency greater than 1 MHz. TV Mc fG 17. A signal transmission method comprising inputting telecommunication signals onto a phase conductor of an electric power distribution and / or transmission network and subsequently receiving said signals, characterized in that said The 5 signals are supplied to and / or received from the network using a communication apparatus according to claim 11 or claim 12. 18. A method of manufacturing an inductor, comprising the step of closing a plurality of rectangular conductive bars with one ferromagnetic sleeve that provides substantially no electrically conductive path through the sleeve in a direction away from the conductive bar, each conductive bar being insulated from the others. 5 The method of manufacturing an inductor according to claim 18, characterized in that the inductor has an inductance of at least 1 μΗ. 20. The method according to claim 18 or 19, characterized in t in that the sleeve is elongate and has a cross section in the shape of a hollow rectangle ¹ Ω. A method according to any one of claims 18 to 21 20, characterized in that the sleeve encloses the conductor and lies close to or contacts, all sides _π conducting rod. A method according to any one of claims 18 to 22 21, characterized in that each of the conductive bars is a different phase conductor with respect to the other bars. Ju 0 (5 30 • · * A * The method of any one of claims 18 to 22, characterized in that the conductive rod has a minimum cross-sectional area of 4.5 mm. A method according to any one of claims 18 to 24 5. , 23, characterized in that the inductor can conduct a current of at least 10 A. A method according to any one of claims 18 to 25 24, characterized in that the sleeve is made of ferrite. A method according to any one of claims 18 to 25, characterized in that the sleeve is made of conductive or semiconductive material. A method according to any one of claims 18 to 15 26, characterized in that an insulating layer is provided between the sleeve and the conductive rod (s).