GB2364834A - RF isolation between domestic power and lighting circuits - Google Patents

Abstract

In a domestic communication system utilising the power line for data communications, apparatus is disclosed for providing Radio Frequency isolation between the power line ring and the lighting ring. The apparatus comprises an RF isolator 106 between the lightening ring 1,3 and the power ring 2,4, the RF isolator preferably being a filter. The apparatus is typically located in the fuse box 105 for a domestic power and lighting ring.

Description

<Desc/Clms Page number 1>Power Line Communications.

A typical 2 storey domestic Electrical Installation ;S Scheo-AI @g@J @cr c@m5%5 ye: 1. Upstairs Lighting Ring Main. 2. Upstairs Power Ring Main.

3. Downstairs Lighting Ring Main. s 4. Downstairs Power Ring Main. . These are typically isolated from each other by fuses or Circuit Breakers for safety and regionalisation.

The complexity of the impedance of this network at Radio Frequencies is a major obstacle to the adoption of Data Communications over the Mains. Spurs and junctions in the system add additional poles and zeros to the complex impedance shown and make system standardisation and installation difficult.

It becomes necessary to limit bandwidth of communications using the media to lower than a desirable rate.

Much of the noise witnessed on the Mains at Radio Frequencies is identified as Short Wave Radio pickup which is difficult to suppress. Additionally there are stringent limits imposed by governing bodies on the level of allowed modulation of the Mains. This is because of Radiation of the Data Communications signals interfering with the said Short Wave Radio Transmissions.

It is well known that the efficiency of an Aeriel (whether used as a Transmitter or Receiver) is strongly dependent on the Height of the Aeriel. Arguably in the above cited installation the Upstairs Lighting (I) will have a greater Aeriel Efficiency than the Upstairs Power (2) as it is at maybe twice the attitude of the latter.

Likewise the Downstairs Lighting (3) will have considerably higher Aeries Efficiency than the Downstairs Power (4) because of its height of, say 2.5 metres versus the power at typically less than 0.25 metres.

It may be safely concluded that the combined Lighting Rings (1,3) will therefore be much more susceptible to incoming interference than the combined Power Rings (2,4).

Moreover the Radiation of unwanted spurious emission from the Lighting Rings will be more than the Power Rings by the same token It should be noted that these comments are also relevent to many other installations than the 2 storey domestic installation cited for example.

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-observed that the main applications for Power Line Communications do not rely on the ability to communicate over the Lighting Rings. It is proposed that considerable improvements in the transmission and reception characteristics of this . communications medium can be achieved by isolating the Lighting Rings from the power Rings at Radio Frequencies in particular with regard to noise.

It is also proposed that the level of modulation of the medium could be higher with similar levels of Electro-Magnetic compatibility: This has additional benefits in the bandwidth of communications which could be achieved-

w -11 th Isolation at the fuse box is feasible using a simple Low Pass Filter which llow the isolated Power Rings to be used much more efficiently whilst havin A) a ect on the Lighting Rings primary function. Such a Filter apparatus can consist of a single LC (Inductor and Capacitor) since the Radio Frequency will be at a much higher Freauencv than the Mains freouency of,

typically 50 or TieM # h a secondWer Filter with a comer frequency of, gs say 4oq w, - q lk 1#10-91 'tc-_ ' e leieterious effects of the parasitic Lighting in -0 at above 1McgaHem. R

" 5i@7 CRE the Current capacity on the Lighting Rings is usually much less than the capacity of the Power Rings se-hat the Filter aparatus may be small, light and economical.

t_ i/2.ru@o;Q.7'(- c3 n'-o`-Y6p_ "built in" to a circuit ' Breaker installation at man acture or, in the case of a fuse box installatioe j110W a fA retro-fitted component@preferably within the same mechanical form factor as the existing fuse.

In addition to the above there is a significant amount of noise generated by phaseswitched dimmers in Lighting circuits which will ;5Q be CZ C@2.@C1-C:e7 @J2r /G@a, A schematic illustration of a typical fuse box configuration 105 is shown in Figure 2. The mains power supply enters the fuse box at 8, and is fed via fuse 11,12,13 and 14 to upstairs Lighting Ring 1, upstairs Power Ring 2, downstairs Lighting Ring 3 and downstairs Power Ring 4 respectively. Figure 3 illustrates a fuse box 105 modified in accordance with the present invention, and using the same numbering scheme as Figure 2. As illustrated, combined fuse/filters 106 are place in the fed to the Lighting Rings 1 and 3, thereby reducing their influence on, and preferably isolating from, the Power Rings 2 and 4.

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Claims (13)

1. -What is-claimed is that RF isolation of the Power and Lighting Rings in a domestic installation can have the following benefits: 1. Reduced High Frequency impedance complexity of the channel used for Data Communications allowing simpler, more universal and higher bandwidth solutions.
2. 2. Reduced susceptibility of the Power Line to ingress of unwanted Radio Frequency interferers due to reduced Rx Aeriel Efficiency through isolation of the major component of these interferers picked up on the Lighting Rings.
3. 3. Reduced Radiation of the Radio Frequency communications signals on the Power Rings by blocking the Radio Frequency from the more-Aeriel Efficient Lighting Rings.
4. 4. Additional isolation of an unwanted noise component from phase switched light dimmers having benefit for the Power Line Communication system and also Radio and Television reception and Computer and other equipment connected to the Power Rings.
5. 5. An apparatus for implementation of the above isolation using a Filter which can be realised in a small, light and cost-effective component.
6. 6. A method for suppressing interference from a lighting ring in an associated power ring, the method comprising isolating the lighting ring from the power ring, preferably by providing a filter between them.

   6. A method for suppressing interference from a lighting ring in an associated power ring, the method comprising isolating the lighting ring from the power ring, preferably by providing a filter between them.
7. 7. A method for suppressing short wave radiation from a lighting ring originating from high frequency communications on an associated power ring, the

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   method comprising isolating the lighting ring from the power ring, preferably by providing a filter between them.

   7. A method for suppressing short wave radiation from a lighting ring originating from high frequency communications on an associated power ring, the method comprising isolating the lighting ring from the power ring, preferably by providing a filter between them.
8. 8. A method according to claim 6 or 7, wherein the filter is provided in a fuse box or circuit breaker.
9. 9. Apparatus for suppressing interference from a lighting ring in an associated power ring, comprising isolating means disposed between the lighting ring and power ring, preferably the isolating means being a filter.
10. 10. Apparatus for suppressing short wave radiation from a lighting ring originating from high frequency communications on an associated power ring, comprising isolating means disposed between the lighting ring and power ring, preferably the isolating means being a filter.

    8. A method according to claim 6 or 7, wherein the filter is provided in a fuse box or circuit breaker. 9. Apparatus for suppressing interference from a lighting ring in an associated power ring, comprising isolating means disposed between the lighting ring and power ring, preferably the isolating means being a filter. 10. Apparatus for suppressing short wave radiation from a lighting ring originating from high frequency communications on an associated power ring, comprising isolating means disposed between the lighting ring and power ring, preferably the isolating means being a filter.
11. 11. A fuse box or circuit breaker comprising apparatus according to claim 9 or 10.

    11. A fuse box or circuit breaker comprising apparatus according to claim 9 or 10. 12.A method substantially as heretofore described, and with reference to the accompanying drawings. 13. Apparatus substantially as heretofore described, and with reference to the accompanying drawings.

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    CLAIMS What is claimed is that RF isolation of the Power and Lighting Rings in a domestic installation can have the following benefits: 1. Reduced High Frequency impedance complexity of the channel used for Data Communication allowing simpler, more universal and higher bandwidth solutions. 2. Reduced susceptibility of the Power Line to ingress of unwanted Radio Frequency interferers due to reduced Rx Aeriel Efficiency through isolation of the major component of these interferers picked up on the Lighting Rings. 3. Reduced Radiation of the Radio Frequency communications signals on the Power Rings by blocking the Radio Frequency from the more Aeriel Efficient Lighting Rings. 4. Additional isolation of an unwanted noise component from phase switched light dimmers having the benefit for the Power Line Communication system and also Radio and Television reception and Computer and other equipment connected to the Power Rings. 5. An apparatus for implementation of the above isolation using a Filter which can be realised in a small, light and cost-effective component.
12. 12. A method substantially as heretobefore described, and with reference to the accompanying drawings.
13. 13. Apparatus substantially as heretobefore described, and with reference to the accompanying drawings.