For DSL products please refer to the DSL installation guides
Q1: What does PLC stand for?
Q2 : What is the HomePlug Alliance?
Q3 : What is “Indoor” PLC?
Q4 : What sort of performances does PLC HomePlug give?
Q5 : What benefits does a PLC network offer?
Q6 : How is broadband Internet transmitted over the electrical network?
Q7 : What does the SoftPlug software do?
Q8 : How is SoftPlug software installed?
Q9 : What data flow speeds can be obtained from computers connected via a NetPlug?
Q10 : What is the maximum distance limit possible between NetPlugs to ensure that data is received correctly?
Q11 : How many NetPlugs can be connected?
Q12 : Do you need a NetPlug or a NetPlug Pro for each piece of equipment you want to connect?
Q13 : Is the data protected?
Q14 : What happens if there is a power cut to the network current?
Q15 : Is a MAC address available via the interface?
Q16 : If you already have an ADSL modem (or other type), can you interface with a NetPlug?
Q17 : How is the available flow shared?
Q18 : What type of equipment can be connected via a NetPlug?
Q19 : Do you need to be a skilled electrician to install PLC?
Q20 : How long does it take to install NetPlugs?
Q21 : Does PLC work with surge protection?
Q22 : Does PLC work with inverters?
Q23 : Will PLC work with a power generator unit?
Q24 : What are the main blocking points when deploying PLC in a house or a flat?
Q25 : What is a phase coupler?
Q26 : What are the main blocking points when deploying PLC in a building?
Q27 : If you live in a block of flats and there is a modem in each flat, can you set up an individual private network?
Q28 : If you live in a building and there is one modem supplying the whole building, can you still have an individual private network?
Q29 : What type of chipset is used in the NetPlugs?
Q30 : How long is the warranty period for PLC products?
Q31 : Are there any constraints on PLC deployment with regard to the European standardization?
Q32 : Does NetPlug conform to European regulations?
Q1: What does PLC stand for?
A1: The abbreviation PLC stands for “Powerline Communications”, which describes the way in which digital information (voice, data, and images) can be transmitted via the electrical network. Various modulation/demodulation techniques can be used for this.
There are two types of PLC:
- “Outdoor” - where transmission occurs over the external electrical network of a house, or a building.
- “Indoor” – where transmission occurs over the internal electrical network of a house, or a building.
In the case of “indoor” PLC – two typicals services are found:
- narrow band – which is generally used for the transfer of information relating to remote commands/equipment control,
- broadband - which is used for the transfer of broadband internet, videos and files.
Broadband PLC technology was developed in the 1990s in the wake of PLC narrow band solutions which had been in existence for a decade. The development of ‘indoor’ solutions was speeded up with the formation of the HomePlug Alliance in North America at the beginning of this century.
Q2 : What is the HomePlug Alliance?
A2 : Homeplug is an alliance of industrial manufacturers and business leaders from associated business sectors (from the technology to the finished product and associated services).
Foundation (March 2000) – The HomePlug Alliance was officially founded in March 2000. There were 13 members at the beginning and this has now grown to 80. Member company profiles range from hardware and software designers, to semi-conductor manufacturers, consumer electronics suppliers and distributors.
Field tests (May 2001) – following the publication of preliminary specifications, tests of the technology were carried out at over 500 sites (domestic housing) to check, amongst other things, 3 important parameters: reliability, communication speed and interoperability.
HomePlug Compliant Programme (November 2001) – the first products, from various manufacturers, were found to be interoperable.
HomePlug Compliant Products (January 2002) – the first official publications on the market availability of HomePlug products.
Q3 : What is “Indoor” PLC?
A3 : PLC “indoor” solutions currently available on the market are almost exclusively based on the HomePlug specification and should be interoperable. The importance of this technology is that it uses an existing wiring network and gives the best distribution throughout a house or building: the access points to the electrical network are the electrical sockets. Therefore, PLC products make it possible to connect equipment via electrical sockets, create a network between equipment and connect to Broadband Internet services, which is one of the main ways of exchanging information at the current time.
The HomePlug standard uses OFDM modulation techniques (Orthogonal Frequency Division Multiplexing) which is based on the simultaneous emission of N carriers on n frequency bands (situated between 2 and 30 Mhz). The access protocol used for this is the CSMA/CA (Carrier Sense Multiple Access / Collision Avoidance) which gives an effective and robust dialogue with the network layer.
Q4 : What sort of performances does PLC HomePlug give?
A4 : When considering HomePlug’s information transmission speeds, it is useful to compare it with ADSL. Just as ADSL uses a frequency range (25k-1, 1MHz) above vocal frequencies to carry Broadband Internet, it is the same with PLC Broadband which uses a frequency band below the traditional 50Hz and the CENELEC band (usually used for narrow band). Therefore it is possible to use Broadband to broadcast information over electrical wiring.
The first official market specification standard is the HomePlug V1.0.1. The data flow that can be achieved by using HomePlug technology over the electrical network is around 14Mbps of raw data. The actual data flow available is generally around 6 to 7 Mbps shared dynamically between up to 16 different potential users.
• Current specifications: HomePlug V1.01.1
• Signal transmission uses the 12-22MHz band
• Coexists on the electrical network with energy distribution of 50Hz and narrow PLC (CENELEC band).
• Raw data flow of 14Mbps / actual data flow 6 to 7 Mbps.
• Data flow shared dynamically.
• Number of potential users: a maximum of 16 simultaneous users (recommendation).
• OFDM modulation (Orthogonal Frequency Division Multiplexing) which is based on the simultaneous emission of N carriers on n frequency bands (situated between 2 and 30 Mhz).
• Access protocol: CSMA/CA (Carrier Sense Multiple Access / Collision Avoidance) which gives an effective and robust dialogue with the network layer.
This has been followed by a “Turbo” standard giving a raw data flow of 85 Mbps. The actual flow available is generally between 35 and 40 Mbps shared dynamically between up to 16 potential users.
The 200 Mbps data flow product samples have been undergoing tests since July 2006. This will allow more flow for high definition videos in addition to Internet traffic, voice services, etc.
Q5 : What benefits does a PLC network offer?
A5 : There are a large number of benefits offered by PLC networks and the main ones are:
• Products from different manufacturers are interoperable,
• No need to lay new cables to connect pieces of equipment,
• Every electrical socket becomes a connection point for access to your PLC network,
• The large number of domestic electrical sockets allows you to be anywhere in the house or building and still be able to distribute PLC signals throughout the premises,
• PLC products are robust and designed for “Plug and Play” which means tha they are simple and easy to set up,
• PLC technology allows you to access three key applications using the same medium: voice services (IP telephony), data (computer) and images (video),
• Internet broadband access can be shared between several users,
• You can network data processing or multimedia equipment,
• All data transmitted over the network is protected by a DES56bits type encryption,
• It is possible to extend an existing cable network and enlarge it over a PLC network.
Q6 : How is broadband Internet transmitted over the electrical network?
A6 : In a similar way to ADSL, which uses high frequencies to carry broadband Internet over telephone lines, NetPlugs use the mains supply to distribute broadband Internet through the electrical wiring installation and also to create a network between the equipment they are connected to.
Q7 : What does the SoftPlug software do?
A7 : LEA developed the SoftPlug software to enable NetPlug users to secure their network(s) and personalise the standard “HomePlug” encryption key.
The software can also be used to obtain an estimate of the quality of the connection between the various connection points linked into the PLC network.
Q8 : How is SoftPlug software installed?
A8 : The SoftPlug software is available on CD-ROM and is included in some NetPlug packs, or it can be downloaded from the LEA website. All you need to do is to insert the CD-ROM in a compatible disc drive of a computer, start the SoftPlug installation programme and follow the instructions that appear on the screen. Once the installation has been completed you can activate the software by double clicking on the icon that appears in the “office” section of the screen, as long as a NetPlug is connected to this computer.
Q9 : What data flow speeds can be obtained from computers connected via a NetPlug?
A9 : The nominal capacity is 85Mb/s but the actual data flow is around 35Mb/s. If the transmission between PLC equipment is adversely affected (by noise, attenuations, echoes and distortions) this increases the error rate and the modulation adapts to a slower flow rate. This limits transmission errors and keeps it below the threshold which would activate the error correction code. This means that the flow will slowly be reduced.
Q10 : What is the maximum distance limit possible between NetPlugs to ensure that data is received correctly?
A10 : The recommended distance limit between NetPlugs is approximately 150m to 200m, within which there should be no obvious deterioration in the transmitted data. However, this will depend heavily on the quality of your electrical network (state of repair) and on any elements that might block PLC communication over the network (e.g. differential circuit breakers). In certain instances, communication will be possible over longer distances and in other cases, only over shorter distances.
Q11 : How many NetPlugs can be connected?
A11 : The optimum number of NetPlugs is 15. This means that 15 users can share the nominal flow capacity. Beyond this, it is possible to connect up to 64 NetPlugs in total (including the original 15). However these 49 potential users can only share the Mb/s flow provided in “ROBO” mode. The share of actual flow is allocated in the order in which the first 15 users access the network. Then, if one of the first 15 users ends their session, they lose their ‘priority’ status and another user (from the next 16-64) can make use of that share of actual flow available (it will be allocated to the first of the 16-64 users who logs at that moment). Please note: because the communications are allocated in rotation, the users who are using the network in “ROBO” mode will slow down all the other network users.
Q12 : Do you need a NetPlug or a NetPlug Pro for each piece of equipment you want to connect?
A12 : Yes, you will need a NetPlug for each piece of equipment that you want to connect to the PLC network. You then use a cable to connect the NetPlug’s RJ45 connector to the network card of the piece of equipment. The only exception to this is if you use a NetPlug hub (PTN008-04) which allows you to connect up to 3 pieces of equipment at once.
Q13 : Is the data protected?
A13 : Yes, all of the data transmitted over the electrical network is encrypted by default. The coding is of the DES56 bits type and the password which generates the encryption key can be personalised to secure your network.
Q14 : What happens if there is a power cut to the network current?
A14 : The modem and the NetPlugs will no longer be supplied and so the traffic will be stopped. There is no battery power supply.
Q15 : Is a MAC address available via the interface?
A15 : Yes, each interface has a MAC address (as well as an individual password).
Q16 : If you already have an ADSL modem (or other type), can you interface with a NetPlug?
A16 : Yes, it is perfectly possible to connect a first NetPlug to an ADSL modem (or other type), to transfer data to electrical network and by using a second NetPlug connect your computer to access the Internet. If you have a modem/router, you can connect several computers. If one of your computers can act as a router, then you can also share Internet access using just an ADSL modem.
Q17 : How is the available flow shared?
A17 : The available flow is shared in a dynamic and transparent way between the various users who are connected simultaneously (up to the limit of 15). The system is sufficiently intelligent to provide more flow to the heaviest application at any given moment.
Q18 : What type of equipment can be connected via a NetPlug?
A18 : You can connect any type of equipment which has a network card with an Ethernet port and which can manage IP protocol. For example, you can connect the following equipment: computer, printer, IP Camera, set top box, IP telephone (SIP) etc.
Q19 : Do you need to be a skilled electrician to install PLC?
A19 : PLC products are designed to be ‘Plug and Play’ and are, therefore, easy to install and configure.
However, there are two main situations which must be considered:
• In the home (a house or flat) there should not be any particular constraints to be found in the domestic electrical network.
• In the case of a building (professional office environment), the electrical network distribution is more complex and it is recommended that the person installing the PLC products should be competent and familiar with the network.
Q20 : How long does it take to install NetPlugs?
A20 : The products really are ‘Plug and Play’.
Q21 : Does PLC work with surge protection?
A21 : If all the equipment is downstream from the same surge protector, then there is no problem. On the other hand, the surge protector contains a filter which will block the frequencies being used. In this case, it will not be possible to communicate between the terminals which are plugged in on either side of the surge protector. We would always recommend that you test the equipment to see how it behaves, as this can vary from one model to another.
However, there are surge protectors which have a special PLC plug (Merlin Gerin).
Q22 : Does PLC work with inverters?
A22 : Our products do not differentiate between the “inverter” current and the “network” current. The important factors for good performance are the attenuation parameters, the level of ‘noise’, distortion, the layout of the network (number of nodes) and the impedances encountered.
Q23 : Will PLC work with a power generator unit?
A23 : Please see the answer above regarding inverters; you need to beware of over-voltage which could damage the power supply to any sensitive equipment.
Q24 : What are the main blocking points when deploying PLC in a house or a flat?
(Please refer to the document on LEA’s website entitled: “Constraints when deploying PLC equipment using private internal electrical networks”)
A24 : When you have a single phase electricity meter installed in your home, all of the electrical sockets are connected on the same electrical phase and have the potential to communicate with each other via a NetPlug module. However, it is still possible to find more dated installations, or a three phase installation, which may disrupt communication in some instances. In these two cases, it is advisable to test the communication between the sockets using LEA’s SoftPlug software. If the sockets are connected to different electrical phases then you will need to install a phase coupler so that the PLC signals can be distributed simultaneously over the three phases.
Q25 : What is a phase coupler?
(Please refer to the document on LEA’s website entitled: “Constraints when deploying PLC equipment using private internal electrical networks”)
A25 : The electricity supply network is made up of 3 phases (phases 1, 2 and 3) as well as neutral and earth. Energy distribution via the public network is structured in this way. However, in a domestic consumer’s house you generally only have one of the 3 phases (phase 1 and neutral or example) which supply the electrical sockets. To supply more energy to a building, for example, three phase is used to supply the building, then distribution switches to single phase for each floor. In this way, there can potentially be 3
separate sub-networks supplied by one three-phase network.
To be able to communicate over the 3 phases simultaneously, you will need to install a phase coupler. This is a passive piece of equipment which allows you to connect the exiting three phase network via either a capacitive or an inductive coupler. A capacitive coupler requires you to physically connect a wire from each phase to a terminal block (however, you must not connect the neutral wire if the terminal block is attached to the coupler). The inductive coupler is cylindrical and can be used to enclose the cables (usually in pairs). However, you will need to use 2 couplers to link the three phase electrical supply (one for phases 1 and 2 and another for phases 2 and 3).
Q26 : What are the main blocking points when deploying PLC in a building?
(Please refer to the document on LEA’s website entitled: “Constraints when deploying PLC equipment using private internal electrical networks”)
A26 : The electricity supply to a building is divided into sectors for safety reasons. The classic structure is generally as follows:
• A low voltage main distribution board, which is the entry point for the three phase public electricity supply, supplies a secondary distribution board on each floor, for example, (generally supplied in three phase from the main distribution board), which includes the protection elements in the form of differential circuit breakers. The secondary distribution board then supplies single phase electricity to the zone that it serves.
• The end/final distribution board: sometimes used to distribute the supply room by room, for example. From an end/final distribution board you can have the potential for 3 separate sub-networks from one three-phase electricity supply. This division of the electrical supply network is used so that when an incident occurs in one part of the network, this can be isolated and not affect the other 2 sub-networks.
There are two potential blocking factors which may affect communication between PLC products:
• The fact that the power supply has to pass through successive distribution boards, which act as powerful attenuation points, may mean that the PLC signals are blocked.
• The fact that there are different electrical phases means that if PLC products are positioned on each separate phase, they will not be able to communicate with each other. These problems should be identified prior to deployment either through examining the wiring plans of the building if available, or through a site audit.
Then, depending on the size of deployment of PLC, you can either circumvent these potential blocks, or to use them to your advantage.
• In the case of a small deployment of PLC products: we will use the example of a zone supplied by three phase power where you want to connect 5 items of equipment. The sockets, or the equipment, are connected to different phases depending on where they are sited. In this instance, you will need to install a coupler downstream from the secondary distribution board. If the PLC products are connected on either side of the secondary distribution board, then you will need to set up an Ethernet bridge via 2 NetPlugs, for example.
• In the case of a large deployment of PLC products: we will use the example of a zone supplied by three phase power where you want to connect 30 items of equipment. The sockets, or the equipment, are connected to different phases depending on where they are sited. However, it is important to remember that you should not deploy more than 16 PLC modules in total. In this situation you can make use of the natural division of the electricity supply to create several groups of PLC products, each connected to a different electrical supply phase. Because each phase is insulated from every other phase, this means that you can create several PLC sub-networks each independent from one another.
Q27 : If you live in a block of flats and there is a modem in each flat, can you set up an individual private network?
A27 : “Indoor” PLC products must be deployed within the domestic section of the electricity supply network, in other words, downstream from an electricity meter. This meter is usually located in the distribution board / consumer unit and houses protective elements including a differential circuit breaker. This acts as a “natural” filter most of the time and makes it possible to set up an insulated network if the modem and router are connected downstream from the meter. All the data transmitted over the electrical supply network is encrypted and cannot be read by any other equipment.
In a similar way, unless a user voluntarily shares his computer or file access, another computer cannot read the contents of a neighbouring computer. However, if this is a critical factor, you can install a “Blocking Filter” (filtre de blocage), in the case where signals may be transmitted outside a desired area.
Q28 : If you live in a building and there is one modem supplying the whole building, can you still have an individual private network?
A28 : We will use the example of a building where you may wish to share Internet access between many individuals, in a residential building providing services (workers hostel/student residence), or even in small business park. In this case it is possible to share Internet access from one central modem as long as there is a regulatory meter upstream from the modem. This is needed to diffuse the PLC signals over the public sector of the electricity meter inside the building to each individual computer. You will need to find a solution for apportioning the costs of each individual broadband access.
Q29 : What type of chipset is used in the NetPlugs?
A29 : NetPlugs use an Intellon chipset based on the North American HomePlug specifications.
Q30 : How long is the warranty period for PLC products?
A30 : The guarantee is for 3 years.
Q31 : Are there any constraints on PLC deployment with regard to the European standardization?
A31 : As with every product that is distributed on the European market, HomePlug PLC products must receive the EC branding before they can be put into circulation and sold freely in the European Economic Area.
Responsibility for obtaining this branding rests with the person who delivers the product into Europe (manufacturer, importer or distributor) and it stands for the certification of the product in terms of electrical safety and electromagnetic compatibility. The branding is awarded by an independent laboratory that is qualified to award this approval. The main constraint relates to the energy emissions from the PLC products and the signal levels which must be controlled. This means that the correct compromise must be found between the power given out which determines the range and the flow available for the end-user and protection of the environment (this is the same whether equipment is for connection to an electrical supply or not).
Q32 : Does NetPlug conform to European regulations?
A32 : Yes, NetPlugs conform to safety standards (EN60950) and to electromagnetic compatibility standards (EN55022/024) and have the EC marking on each product.