For those who missed the first part or want to remember the first part.
For those who understand what an automatic machine and an RCD are, why they are needed, what they protect and from what, go to the section.
Part two
Let's look at the relationship between energy and end IT equipment, and we'll look into the question - in what cases of power outages the operating system is guaranteed to work without failures.
Issues of switching to a backup power source
Power supply for information equipment is organized with redundancy. Let's consider the organization of power supply in terms of SHBP-BRP-BP (uninterruptible power supply panel-distribution unit power supply unit food). The types of reservations are as follows:
- Redundancy of cables to the rack, equipment, using separate power distribution units, PDU (Figure 1)
- Redundancy of power buses in the power supply panel, using separate power distribution units, PDU (Figure 2)
Redundancy using a rack-mount load switch, rack-mount ATS (SPN, also known as ATS) (Fig. 4)
To switch between the main and backup inputs, the following can be used:
- in the field information systems: ABP/STS (Static Transfer Swith) cabinets for systems high power, to switch to power from a backup UPS while a full-fledged 2N system or combinations of N+1 systems are operating;
- in the field of power supply systems of various types of ATS circuits (on contactors, on controllers);
- at the server rack level: automatic high-speed rack-mount ATS\ATS (Automatic Transfer Switch);
- at the level of specific information equipment: duplicated power supplies.
The customer is installing a local server room along with IT infrastructure on two floors for the company’s office. At the stage of discussing the power supply system, he has a desire to supply all information equipment with one power supply unit (PSU), leave the second slot for the server PSU free, and mount a single rack-mount ATS on the entire rack. (Fig. 4, diagram).
Appearance the back side of the server with duplicate power supplies 
How the Customer justified his desire:
- Cost savings ($500-800 per rack device)
- You can install two simple PDUs and use them for power distribution after the ATS
- Absolutely similar level of system reliability compared to the classical distribution method
- cost (savings) of capital expenditures during implementation (CAPEX)
- cost of depreciation costs, maintenance of spare parts, labor costs of client personnel (OPEX)
- comparison of operating algorithms and switching time to the backup line in both options, checking for “single points of failure”
- the level of risks of freezing and/or rebooting of operating systems of information equipment, crashing of information services that run on them.
Some excerpts from the article
In recent years, state standards in the field of measuring electrical energy parameters related to CE have been actively developed and have been repeatedly revised
" An important change was the replacement of GOST 13109-97 “Electric energy. Compatibility technical means electromagnetic Standards for the quality of electrical energy in power supply systems general purpose» according to GOST 32144-2013. These standards define a different range of power quality indicators.
But how fast is it? How to determine the time in milliseconds during which the customer’s service (and server) will not crash and the operating system will not go into a “critical error”?
There is a CBEMA (Computer and Business Equipment Manufacturers Association) standard, which after some adjustments is now known as “ITIC curves” (Information Technology Industry Council), and its variants are included in the IEEE 446 ANSI standards. According to these standards, electronic circuits power supplies must remain operational for 20 ms (or 0.02 seconds, that is, a period).
Those same ITIC curves
According to the requirements for power supplies for server and computer systems Server System Infrastructure we can say that the power supply parameter Tvout_holdup during a power failure, it ensures the operation of information equipment for at least 21 ms. That is, the full network period is the guaranteed time of normal operation of a server or switch. Parameter Tpwok_holdup defined as a minimum of 20ms.
Some details on SSI parameters can be found here
Help: Hold-up time is the time period during which the power supply can maintain output voltages within certain limits after a loss of supply voltage at its input. In most computer power supplies, the Hold-up time also characterizes after what period of time the power good signal (PWR_OK) will tell the system that the voltages generated by the power supply are unstable (for computer power supplies this parameter is usually more than 16 ms).
Here is one of the tables from the document
And this is a diagram (time-line) with regulated algorithms for the operation of the power supply
Now let's see what switching times APC claims for, for example, the AP7721 brand rack load switch. We see that here we usually have 8-12 ms, but 18 ms is the maximum switching time.
We can conclude that the switching time to the backup input for the rack transfer switch meets the operating specification of the power supply server equipment. It turns out that there will be no failures in the operation of information equipment.
Summary table of system element timings
What about the economic component and which option is more profitable and fault-tolerant?
Suppose we have three small servers in a rack, into which we can put two power supplies and three devices with non-redundant power supplies. All are critically important and the failure of any device will cause the customer’s entire system to fail. In any case, we will need a rack-mount load switch. This is about 18 thousand rubles.The customer states that they do not need PDUs, which means that the budget will only include the cost of the ATS - the same 18 thousand rubles. As a replacement for power distribution units (PDUs), the Customer proposes to use power distribution “on board” the rack transfer switch. The Customer also plans to buy servers with two slots for power supplies, but complete with one power supply for the sake of economy.
The classic option involves a set of 2 PDUs - about 32,000 rubles, 3 additional power supplies for servers at $500 each for 84 thousand rubles in total. ATS for the same 18 thousand rubles. Having added everything up, we understand that the classic solution will cost the Customer approximately 134 thousand rubles.
It seems that indeed, the Customer is right, the money is completely different. But let's look from the point of view of fault tolerance and maintainability of both options:
Customer option: The single point of failure is the rack transfer switch. If something happens to him, then we lose the entire stand. This means that you need to have spare parts and accessories right on the site, which adds 18,000 rubles to the estimate. Power supplies in servers are located one at a time, they are also points of failure. This means that it is advisable to have at least one, or better yet, all three power supplies in reserve on site. Let’s assume that we need three power supplies in spare parts – that’s another plus of 36 thousand rubles. It is necessary to check the power that the rack ATS can switch. Now we proceed from the fact that 3 kW or 16A is enough for all the equipment in the rack. If we need a 32A (7kW) ATS, then it will be significantly more expensive (more than 100 thousand rubles). That is, the budget of the Customer’s option with a detailed consideration of reliability grows to 160 thousand rubles. Moreover, in the event of an emergency, despite the fact that spare parts will be on site, down-time will be needed to replace the device.
Single point of failure (SPOF, Single Point Of Failure) - a node, communication line or object of a data availability system, the failure of which can destroy the entire system or cause data unavailabilityOpen Technologies Option: By, but if necessary, ATS is added for small network equipment with a single power supply.
The point of failure is the same ATS. If something happens to him, then we lose the entire stand. We agree that it is necessary to have spare parts and accessories right on the site. But in our case, if only the ATS fails, then this can only affect the operation of the switches and auxiliary equipment. The servers themselves will continue to operate quietly. Power supplies in spare parts are not needed. Since if one of the duplicated power supplies fails, the server will continue to operate on the remaining one, and, most likely, will wait for a new power supply from the vendor, regardless of the remoteness of the site.
Interpretation of the term SPOF in relation to IT systems
Single Point of Failure (SPOF, Single Point Of Failure) is a node, device or circuit point, the failure of which can disable the entire system and cause unavailability of data and services. Considered during the development and design of any critical systems. The complete absence of single points of failure leads to a significant increase in capital costs during implementation, therefore the criticality of the operation of a particular system or service is determined at the design stage based on the project budget, as well as the wishes and requirements of the Customer. We always find an ideal solution for each Customer, identifying several options for project implementation and offering them to the Customer. As a result, at the project delivery stage, the customer receives exactly the solution he wanted in terms of price/quality/reliability ratio.
Thus, it is possible to connect all the rack equipment to a single ATS, but it is not rational, since in this case we get a single point of power failure. Purchasing servers with duplicate power supplies is preferable in any case, since fault tolerance at the level of information equipment increases significantly.
The rack load transfer switch ensures correct and almost instantaneous switching to the backup input, the information equipment will not even sense it, software products And OS will continue to work correctly. Rack-mount power distribution units are needed in any case and there is no need to skimp on them. Apparent savings on capital costs for power distribution can result in unsolvable operational problems, for example, the need to “turn off” the entire rack just to move the ATS to another unit or revise a rack load switch. In any case, for duplicate power supplies there must be spare parts, but it is not always possible or available.
Appearance of a removable server power supply:
The use of a rack-mounted ATS has its own characteristics
For example, the power of such an automatic transfer switch is limited, and it can switch a complex of loads that are relatively weak in terms of power consumption. There are questions about the number of power output connectors. For example, the aforementioned ATS AP7721 is equipped with C14 type connectors at the input, which means a maximum switching power of 2.5 kW. For higher load power there is a 2U model AP7724, which is equipped with a 32 A connector at the input, that is maximum power equipment can be up to 7 kW. This means that a typical rack with equipment can be completely connected to this ATS. However, the price of such a solution will be more than 100 thousand rubles.
The operation of information equipment with two power supplies was well described in an article by Vadim Sinitsky @dimskiy. As you can see, there are advantages and disadvantages. And the availability of backup power supplies for information equipment is necessary in any case, especially if the facility is located outside the area of rapid delivery of a power supply from the vendor. In addition, we would like to note that online calculators for calculating the capacity of new servers from vendors can only be used as a guide for system administrators, Customer's personnel.
The real possibilities of connecting a new powerful server to an existing rack should be assessed taking into account the original power supply design, the current state and load of the power supply network of the rack, server room, UPS, generator…. In terms of rack connectivity, it's also worth considering:
- current capabilities of PDUs, such as free connectors in them
- ratings of the circuit breakers in the panels and the cross-section and phasing of the cable line to the rack.
How is your rack distribution system built?
What is the power supply resource for IT equipment and the algorithm for their software backup?
Which PDUs do you prefer to use: basic, with monitoring? How useful is the “controlled PDU/PDU” function in practice and has it ever helped you?
Only registered users can participate in the survey. , Please.
The PLC adapter from Rostelecom is a device that allows you to transmit an Internet signal over an electrical network. Such equipment will help get rid of the installation of additional wires in an apartment or private house.
Nowadays, most people have a wireless network in their own home or apartment. You might think that Powerline (aka HomePlug), which uses your home's electrical wiring as a wired network to transmit data, is an outdated and useless technology.
This assumption will be incorrect. Yes, Wi-Fi is convenient and fast - 802.11n technology is widespread, and the latest 802.11ac class routers provide connections at speeds of up to 1300 Mbps.
Important: the simplicity and reliability that Powerline offers, wireless technology still cannot provide. It is not intended to replace a Wi-Fi network. These technologies complement each other.
What is a Powerline network?
Powerline is essentially a wired network. Let's assume you have a broadband router in the hallway and a smart TV in the living room that doesn't support wireless. The only way to enjoy digital TV is to run an Ethernet cable from the router along the hallway and the living room floor. You can try to hide the cord under the baseboard. But, if the apartment has recently been renovated, starting it over again because of one cable will not be the best idea.
PLC adapter from Rostelecom will not be required complex circuits to connect it. It's practically invisible. The basic kit comes with two Powerline adapters and several short Ethernet cables.
The scheme is simple, we connect one Ethernet cable to the router and the other to the first adapter. Then plug it into the nearest outlet. We connect the Ethernet cable to the HDTV and the second adapter. We insert the latter into the nearest outlet. The adapters automatically discover each other (without drivers and without a lengthy configuration process) and connect. This allows data packets to be transmitted from the router to the TV through electrical wiring in the walls.
What is the connection speed?
When the first HomePlug Powerline standard was introduced in 2001, data transfer speeds were limited to 14 Mbps. But the latest PLC adapters for Rostelecom support Gigabit class networks, providing positive reviews even among GPON Internet users.
Why use Powerline networks?
If you already have a wireless hub, you may not see the point in purchasing Powerline adapters for your home network. But the technology has a number of advantages over Wi-Fi, namely constant speed, reliability, security and ease of use.
By setting up a network using a PLC adapter from Rostelecom, you can cover places where wireless connection It has low quality due to a large number of overlaps or other interference in the signal path. This option will also be convenient when connecting non-Wi-Fi enabled equipment, such as legacy game consoles, without cluttering your living room with Ethernet cables. Powerline is a neat and efficient network solution.
Important: The technology is safer than wireless networks. Because data travels over copper wires in your home, you can be sure that only you will have access to the connection.
Some PLC adapter kits allow you to additionally protect the connection using a password.
How do Powerline networks work?
Sending signals through electrical wires at home is not a revolutionary idea. Energy companies began sending control signals through such networks as early as 1920. This allows electricity meters to know when to switch to off-peak speed. Electrical wiring in homes can support different frequencies. Typically 50/60Hz signals are used. Additional data can be transported over the same wiring to more high frequencies without causing any interference.
The first of the standards made it possible to achieve a data transfer rate of 14 Mbit/s. Already in 2005, the upgraded version increased the throughput to 200 Mbit/s, which is more than enough for streaming video.
Before connecting the PLC adapter, you need to inquire about its support for your type of electrical network, provided that the purchase was not made from the Rostelecom operator. The device will make connecting to the Internet easier for many users who, for various reasons, cannot lay an Ethernet cable.
PLC technology(Power Line Communication) is a modern telecommunication technology based on the use of power networks for high-speed information exchange. Experiments on data transmission over the electrical network have been carried out for quite a long time, but low transmission speeds and poor noise immunity were the bottleneck of this technology. But progress does not stand still, and the advent of more powerful DSP processors (digital signal processors) has made it possible to use more complex signal modulation methods, such as OFDM modulation (Orthogonal Frequency Division Multiplexing), which has made significant progress in the implementation of PLC technology.
It should be taken into account that in its relatively short period of historical development, the use of this technology encountered some difficulties, which I will talk about a little later.
PLC technology capabilities
Connecting to the global Internet is a widely developing business; Internet providers provide communication services almost everywhere in the office and at home. Today, a large number of high-speed backbone networks have been built and are in operation, however, connecting end users to them still remains a serious, often bureaucratic problem. Today, most final connections are made by laying a cable from a high-speed line to the consumer's apartment or office. This is perhaps the cheapest solution, but for a number of reasons, laying the cable is extremely difficult or even impossible. This is often caused by the delimitation of influence zones between Internet providers. In certain territorial areas, the end client is forced, in order to connect to the Internet, to contact the provider - which is the direct owner of the communication node, which is geographically close to the client’s node.
Not all providers are able to forward a fiber optic cable through certain objects to the end client without permission, and a standard UTP cable maintains a stable connection with a length of no more than 100 meters. Thus, in some areas, it is simply unprofitable for providers to organize high-speed Internet access, due to the strategic cost-benefit of specialists and equipment.
So why not use the power electrical communications system already available in every building. In this case, any electrical outlet in the building can become an exit point to global network Internet. Moreover, with proper planning of this type of connection, all that is required from the consumer is only the presence of a PowerLine modem (network adapter), appropriately configured for communication with a similar device, installed, as a rule, in the electrical panel of the building and connected to a high-speed Internet channel.
Technology such as PLC can be used to create local network in small offices where the main requirements for the network are ease of implementation, device mobility and easy expandability. At the same time, like everyone else office network, and its individual segments can be built using PowerLine adapters. Very often there is a situation when it is necessary to include in already existing network remote computer or network printer, located in another room or even at the other end of the building. Using PowerLine adapters, this problem can be solved in 15 minutes. Similar solutions are possible with other connection types, but PLC is not intended to be an absolute replacement for them, but is a powerful alternative. Having some restrictions, this system is no different from any other type of Internet connection.
Problems of PLC technology development
It is for the successful solution of current communication problems that PLC technology was created. But here we should make a reservation! Such solutions are not a panacea, because everyone knows the popularity of WI-FI networks, through which you can easily carry out wireless data transfer, as well as 3G and 4G.
In Western countries, this technology is widely used by local providers and ordinary users, and PLC is also used by some Internet providers in the Russian Federation. In general, this technology seemed and still seems very promising for Western communication systems. The local power grids are regularly modernized, and electrification has affected even the most remote territories and regions.
But wireless technologies are more attractive to both Western and domestic consumers. Wireless network and first generation encryption methods for the transmitted signal were not reliable enough for use in critical industries. Left much to be desired and throughput wireless communication channels, the speed of such connections. In the process of their development and improvement, wireless solutions have taken precedence over PLC and even over standard cable connections. New technological WI-FI standards networks. Repeater devices have begun to be used everywhere to expand the coverage area of a wireless signal. It should be noted that in many countries of the world, under civil systems wireless communication, the most advantageous frequencies have been allocated for the needs of ordinary citizens. In our domestic realities, such frequencies are assigned to military and government agencies.
However, no matter how optimistic the results of experimental PLC networks abroad may be, in our country this technology has encountered a number of difficulties. Our electrical wiring is made primarily of aluminum rather than copper, which is used in most parts of the world. Aluminum wires have poorer electrical conductivity, which leads to faster signal attenuation.
Another problem was that we still have not resolved the main issues of legal regulation of the use of such technologies. However, the last problem is also relevant for the West.
It was believed that this technology, or rather compatible devices, would fill the HI-TECH equipment market in huge shares. New opportunities opened up when implementing smart home ideas, where all household electronics are connected into a single information network with the possibility of centralized control. The electrical network is an ideal medium for transmitting control signals between household appliances operating on a 110/220V network. But even among smart home solutions, it is the wireless method of exchanging short control signals that are not particularly demanding on connection quality and bandwidth that has gained the upper hand.
All these factors have held back and are holding back widespread development. However, PLC is successfully used in practice by some Internet providers in new buildings, with modern electrical equipment, as well as by enthusiasts in apartments or country houses. There are a considerable number of hybrid devices on the market that combine both PowerLine and WI-FI technology simultaneously!
Development problems and features of PLC technology was last modified: March 3rd, 2016 by Admin
Power line communications (PLC) technology allows you to introduce an automated control system into a new or existing infrastructure, minimizing costs both when developing an infrastructure project and when laying additional data networks.
The idea of PLC dates back to 1838, when Edward Davey proposed using similar technology to remotely measure battery voltage levels on the Liverpool Telegraph System. However, only with the advent of modern components that make it possible to implement the necessary computing power on a budget (OFDM, which will be discussed below, “gathered dust on the shelf” for quite a long time due to the complexity of implementation), PLC technology really became relevant and accessible in the industrial and domestic sectors , providing the necessary reliability, speed and ease of deployment.
Currently, PLC is used mainly in energy metering systems and simple automation (lighting, machine drives). Less commonly, this is the “last mile” in data networks (Internet), in voice communication. The development of technology has made it possible to use not only in networks alternating current. The lack of additional wiring has proven so attractive that PLCs are now even being integrated into vehicle wiring systems.
Technology
The basis of PLC is modulation of the phase of the power line, using it as a carrier. There are four modulation options: frequency ( FSK - Frequency Shift Keying), frequency with separated frequencies ( S-FSK - Spread Frequency Shift Keying), binary phase ( BPSK - Binary Phase Shift Keying) and orthogonal frequency division multiplexing ( OFDM - Orthogonal Frequency Division Multiplexing). The choice of option is determined by two criteria - the efficiency of using the frequency band and the complexity of the implementation, which, in turn, determines the data transfer rate and noise immunity. OFDM is the fastest and most noise-resistant, but is difficult to implement, as it is demanding on computing resources, while BPSK and FSK are easy to implement, but provide only low speeds. FSK requires synchronization at phase zero crossings, which limits its use to AC networks only.
In addition, PLC systems are implemented taking into account the requirements of standards (IEC 61334, PRIME, G3 and others) or local regulatory requirements (CENELEC, FCC, etc.).
Tables 1 and 2 show comparative characteristics main modulation options, standards and requirements.
Table 1. Basic PLC Standards Supported by TI
| Standard | Modulation | Range frequencies, kHz |
Quantity subcarriers |
Maximum transfer speed data, kBaud |
|---|---|---|---|---|
| IEC 61334 | SFSK | 60…76 | 2 | 1,2…2,4 |
| PRIME | OFDM | 42…90 | 97 | 128 |
| G3 | OFDM | 35…90 | 36 | 34 |
| G3-FCC | OFDM | 145…314 | 36 | 206 |
| 314…478 | 36 | 206 | ||
| 145…478 | 72 | 289 | ||
| P1901.2 | OFDM | 35…90 | 36 | 34 |
| P1901.2-FCC | OFDM | 145…314 | 36 | 217 |
| 314…478 | 36 | 217 | ||
| 145…478 | 72 | 290 | ||
| PLC-Lite | OFDM | 35…90 | 49 | 21 |
Table 2. Regulatory Instructions
| Region | Instructions | Frequency range, kHz | Notes |
|---|---|---|---|
| Europe | CENELEC A | 3…95 | for electricity suppliers |
| CENELEC B | 95…125 | ||
| CENELEC C | 125…140 | for custom applications (CSMA standard) | |
| CENELEC D | 140…148,5 | for custom applications | |
| USA | FCC | 10…490 | — |
| Japan | ARIB | 10…450 | — |
| China | EPRI | 3…500 (3…90) | — |
PRIME
The PRIME Alliance has developed a standard that can be adapted to the parameters of the physical transmission medium. It was found through experimentation that 96 subcarriers are required to achieve optimal data transmission results. The network topology is tree-like, with two types of nodes - basic (root of the network tree) and service. Service nodes are capable of operating in two modes - terminal and switch, and switching between modes is possible at any time, depending on the requirements of the network, and the switch mode combines the terminal mode. In total, the network can have 1200 nodes, 32 of which can be in switch mode, and up to 3600 connections can be addressed.
Main advantage this standard in the openness of technology, high speed data transfer and support from a huge number of manufacturers, which ensures interchangeability of equipment, as well as the ability to operate in SFSK mode, ensuring compatibility with older equipment.
G3
Unlike PRIME, the G3 standard was initially developed by Maxim Integrated for the French company ERDF, and only later more than ten companies merged into the G3-PLC Alliance, which made G3 open.
G3 has a more complex coding system (Reed-Solomon code), a mesh network topology with a maximum number of nodes - 1024. The standard is more noise-resistant than PRIME, but the data transfer speed is significantly lower.
Besides topology and speed, G3 has two major advantages over PRIME: the first is the ability to communicate through transformers. Considering that the communication range without repeaters can be up to 10 km, this feature reduces the number of hubs to the most efficient number, which reduces the overall cost of the project.
The second feature is the presence of a 6LoWPAN layer, which allows the transmission of IPv6 packets for integration with the Internet.
G3 does not support SFSK devices, but allows parallel operation with them on the same line.
PLC-Lite
In addition to international standards, there are other solutions. Texas Instruments offers its own PLC-Lite standard.
The benefit of this standard is a more flexible approach to PLC implementations, equipment designers can optimize characteristics to improve data transfer, and where G3 and PRIME struggle with interference, PLC-Lite can handle it successfully. In addition, PLC-Lite has a low implementation cost, allowing it to be used in low-cost projects.
There is another important property of PLC-Lite: for small tasks it is possible to use a PLC modem microcontroller, which eliminates the need for a host controller. This simplifies the development of devices so much and reduces the cost that it becomes economically possible to integrate PLC modems into a network at the household “switch-light bulb” level. Below we will describe one of the projects showing the effectiveness of such a solution.
Hardware implementation
To implement this technology, PLC modems are used, which can be divided into three components: a matching module with the power network, analog and digital parts. The implementation of modems is varied - there are both single-chip solutions and multi-element ones. Figure 1 shows a typical PLC modem circuit for OFDM (FSK and G3 will additionally require a Zero-Cross detector).
Rice. 1.
To provide analog signal processing, TI offers chips AFE030 , AFE031 And AFE032, which differ in the size of the output current load of the transmitter, the number of phase zero crossing detectors (two for AFE030 and AFE031, three for AFE032) and the ability to program the filter (AFE032). These chips allow FSK, SFSK and OFDM modulation to be implemented in accordance with CENELEC requirements. A block diagram of microcircuits using the AFE031 as an example is presented in Figure 2, and detailed functionality and features are described in our magazine earlier: NE No. 10/2012: “Any protocol - over the wire: Texas Instruments solutions for PLC data transmission systems” and NE No. 7/2011: “Concert for meter and network: Texas Instruments PLC modems.”
Rice. 2. Block diagram of AFE031 - analog part of the PLC modem
The “brain” of the modem is a microcontroller of the C2000 family from TI, optimized for operation in PLC modems as a DSP. IN currently TI offers several solutions based on regional requirements and standards, taking into account the optimal parameters required. For example, if an extensive network of an energy metering data collection system is required in accordance with CENELEC and G3 and/or PRIME standards, then the ideal solution would be a PLC modem based on F28PLC83 in conjunction with an analog block AFE031 , the same solution using FlexOFDM (PLC-Lite) will allow communication in conditions of strong interference. If a relatively simple point-to-point system is required, then a pair F28PLC35/AFE030 PLC-Lite standard is best suited. In particular, the F28PLC35/AFE030 is ideal for building connections within one object, for example, for controlling/automating lighting, water supply and other systems.
Of course, the solutions can be used comprehensively, for example, the inexpensive F28PLC35/AFE030 can be used to transfer data from an energy meter to a home display and to a data collector, a more powerful one - from a collector to a data center.
Table 3 shows the comparative characteristics of the above solutions.
Table 3. TI PLC Modem Solutions
| Peculiarities | F28PLC35/AFE030 (PLC-Lite) | F28PLC83/AFE031 (CEN-A/BCD) | F28M35 /AFE032 (FCC) |
|---|---|---|---|
| Regional frequency range | CELENEC A, CENELEC BCD half band | CENELEC A, B, C, D with Tone Masks | CENELEC A,B,C,D, FCC, ARIB |
| Standard | FlexOFDM | PRIME/G3/IEC 61334/FlexOFDM | P1901.2/G3-FCC |
| Transmission speed data, kBaud |
21 | 64…128 | 200 |
| Price | very low | low | average |
| CPU, MHz | 60 | 90 (VCU-I) | 150 (VCU-I) |
| Advantages | low cost OFDM reliability flexible band selection high performance NBI CLA for CSMA/CA MAC applications | multiple standards SW certified improved reception algorithm simple user interface | many standards high performance additional reliability methods Adaptive Tone Mask proven by practice |
| Use | In-Home Display (IHD) Home Area Network (HAN) | Automatic Meter Reading (AMR) Advanced Metering Infrastructure (AMI) In-Home Display (IHD) (Home Area Network) HAN Energy Gateway | Automatic Meter Reading (AMR) Advanced Metering Infrastructure (AMI) Electric Vehicle Supply Equipment (EVSE) In-Home Display (IHD) (Home Area Network) HAN Energy Gateway |
Practical use
The ability to easily integrate PLC technology virtually anywhere there is a power network has opened up great opportunities for utility companies to implement consumer control and feedback with the consumer. Equipping metering devices with PLC modems will allow:
- simplify fiscal matters;
- collect statistics on the quality and quantity of energy supply with a very precise time reference;
- forecast energy supplies;
- assess the condition of the lines;
- promptly intervene in the current state, for example, provide priority connection to consumers in emergency situations;
- reduce the likelihood of emergency situations through “targeted preventiveness” in the maintenance of energy transmission lines.
On this moment there is a need for meters for housing and communal services various types. TI is ready to offer various solutions (including software and debugging tools) that allow you to build a “smart” network to suit almost any requirements (Figure 3). Let's consider practical example energy accounting based on these solutions.
Rice. 3.
Typically, homes have at least three meters - an electricity meter and two water meters. However, there can be much more of them: there are projects of houses where there is gas supply, water supply is supplied twice, which requires the presence of four meters. And, if there are no particular problems with the electric meter, then reliable communication with the others must be carried out using a different interface. And the existence of each counter individually in the network does not seem practical. Let’s add the need for emergency shutdown of power supply systems (and abroad, also shutdown at the end of payment) - this will require additional sensors and actuators. In addition, the end user is extremely curious about how much, where, when and what was spent, and the ability of a “smart” network to provide him with such information is much higher than that of a simple meter. This means that an information display module is needed. Now let's multiply all this by a certain number of apartments in a house, area...
Therefore, an important element in the automated measurement infrastructure (AMI) is the data concentrator (Figure 4).
Rice. 4.
Conventionally, the hub module can be divided into four parts: the main application processor, a communication module with a data server (and with some meters) based on a PLC modem, a power supply and interface modules for communication with meters and users via many different interfaces.
The hub is based on a TI family processor SitaraAM335x(ARM Cortex-A8) or families Stellaris(Cortex-M4) or ARM-DSP, which allows the developer to choose the most cost-effective solution depending on the technical conditions.
A large number of interfaces on the data concentrator will allow you to collect data from meters or provide communication with the server where the use of PLC technology for some reason was impossible.
With the ability of TI's PLC modem processor to perform custom applications, scheme automated system measurement becomes quite simple, and its construction is very flexible: the electric meter, together with a PLC modem and additional interfaces, is capable of collecting data from other meters, controlling actuators and displaying information for the user. Figure 5 shows standard solution an electric meter designed for wide versatility.
Rice. 5.
Typical solutions for gas and water supply meters are based on TI series microcontrollers MSP430 , characterized by low current consumption, which makes battery power possible. Figures 6 and 7 show that, in addition to the main measurement, display and communication systems, there is an RFID module. which provides an advance payment regime for gas and water supply services.
Rice. 6.
Rice. 7.
In addition to the ability to monitor readings directly on meters, the smart network includes an In-Home Display - a central information display (Figure 8), thanks to which there is no need to check each meter individually, everything can be seen at once. This allows the meters to be installed more conveniently and/or without disturbing the design of the house - as a rule, in normal cases, either access to the meter is difficult and reading the readings becomes a problem for the user, or the meter becomes an unattractive part of the interior.
Rice. 8.
Equipping housing and communal services with systems of this kind allows you to get many positive aspects:
- centralized collection of information on the amount of energy consumed from all network users makes it possible to timely issue invoices indicating the exact amount, introduce various tariff systems and implement preventive and restrictive measures when the limit is exceeded or energy consumption rules are violated;
- more competent distribution of funds for the modernization and repair of systems based on information about failures in energy consumption systems and needs in individual areas;
- the ability to quickly localize and resolve emergency situations.
In addition, the system is so flexible that it allows significant additions to be made without any major overhaul. For example, integrating gas leak sensors into the system will allow for preventive safety measures.
Unfortunately, the implementation of such a system requires the solution of serious organizational issues (and some capital investments) on the part of energy supply companies and housing and communal services. However, such a system fully justifies its existence for the sake of user convenience.
Automation of measurements is just one application of PLC technology. An important part is the opportunity automated control various systems, such as lighting, ventilation, electric gate and blind drives, alternative power supply systems (Figure 9).
Rice. 9.
The extensive capabilities of the TI Data Hub microcontroller provide a range of convenient and sometimes necessary control capabilities:
- control and management of all systems;
- remote connection via the Internet;
- automatic switching on of lighting based on a calendar or sensor;
- automatic connection of an emergency power source with “smart” connection of consumers;
- selective or general shutdown emergency systems;
- remote control from a remote control (for example, opening a garage door).
Of course, there are alternative solutions: proprietary solutions from manufacturers of lighting, electric gate drives, etc. The advantage of a solution based on TI PLC components is the ability to integrate into an existing facility without any significant changes, as well as its versatility.
Ultimately, a single control is much simpler, more reliable and more convenient (a good example is two options for audio-video equipment: one manufacturer with a single control panel and several different ones, with the corresponding number of remote controls), and makes it possible to easily expand the system.
In some cases, the use of PLC modems may be the only simple and cost-effective solution. Consider the following typical example: a cottage, a living room with four entry points (street, courtyard, stairs to the second floor, kitchen). Turning on the lighting in the living room becomes problematic - a cheap solution (one switch) is simply inconvenient. It is convenient to have four crossover (pass-through) switches, one at each entry point. This will allow you to control the lighting from any point without making unnecessary movements (when turned off - in the dark). But for implementation, it is necessary to run three wires to two switches, and four to another two.
And this is the control of one lamp. If there are two or more groups of lamps in the chandelier, the number of wires increases sharply. The cost of a two-key cross switch, even without taking into account the cost of wires, is already comparable to the cost of a PLC modem. The cost of installing such a system is also quite high. Let's try to create the same system with the ability to adjust the brightness, and we will have to integrate something remote directly into the lamp.
The use of a PLC modem manufactured by TI eliminates the need to lay additional cables, moreover, it forces you to take a slightly different look at the classic system: the PLC modem, acting as a switch and regulator, can be integrated not only into the connection point of the switch, but also into a line of sockets . Connecting lamps is also simplified (no wiring with switches is required). The number and nature of lamp control becomes unimportant. The design of switches (regulators) has endless possibilities. In addition, integration into a common “smart” network allows you to implement an emergency lighting system without laying a single additional cable.
Debugging tools from TI
To develop systems based on PLC technology, TI offers the following:
- MODEM DEVELOPER'S KIT
- TMDSDC3359
The TMDSPLCKIT-V3 set includes two PLC modems, two control cards based on TMS320F28069 , has a built-in USB-JTAG emulator and all the necessary cables. Also attached software for PLC, supporting OFDM (PRIME, G3 and FlexOFDM) and S-FSK standards, and the Code Composer Studio v4.x development environment with a 32 KB executable code size limit. Analog signal processing chip used - AFE031 . The appearance of one of the modems is shown in Figure 10.
Rice. 10.
Data Concentrator Evaluation Module TMDSDC3359(Fig. 11). This product allows you to debug data concentrator-based systems. Built on a processor AM335x Sitara ARM Cortex-A8 family with OS Linux BSP. The board has wide peripherals:
- 2x USB;
- 2x Ethernet;
- 2x RS-232;
- 3x RS-485;
- infrared transceiver;
- temperature sensor;
- Sub-1GHz and 2.4GHz RF; AM335x.
Rice. eleven.
It is possible to connect the module for communication via three-phase networks. Pulse block power supply is built in.
Supported standards: G3, PRIME.
Conclusion
Using PLC technology for data transmission has many advantages, allowing you to quickly and at minimal cost deploy a “smart” network that can quickly adapt to the required tasks, and thanks to the capabilities of the G3 and PRIME standards, to the data transmission environment.
Texas Instruments provides a complete solution, from chips to software, for implementing PLC networks in control and information acquisition systems. Due to its flexibility, this solution allows the system to be implemented for any type of protocol and satisfies possible regulatory requirements.
The COMPEL company is the official distributor of Texas Instruments and can provide developers with both the processors and analog microcircuits themselves, and development tools for implementing their own PLC projects.
Literature
4. Andrey Samodelov. Concert for meters and networks: PLC modems from Texas Instruments//Electronics News No. 7/2011.
5. Alexey Pazyuk. Any protocol - over the wire: Texas Instruments solutions for PLC data transmission systems // Electronics News No. 10/2012.
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TI's Bluetooth Smart SensorTag makes it easy to develop Bluetooth apps on AndroidTM 4.3 devices
Company Texas Instruments announced the release of an application for Android OS called Bluetooth Smart SensorTag, following the integration of Bluetooth Smart Ready app support into Android 4.3 "Jelly Bean" OS. New product available for free download by the address www.ti.com/sensortag-app-android-eu, removes barriers for app developers wanting to take advantage of the millions of Android smartphones and tablets that will soon be Bluetooth Smart Ready. Developing a block of Bluetooth Smart applications, now supported by Android and iOS, has become easier and faster with the help of a development kit Sensor Tag on the base CC2541. The kit includes six versatile sensors on one board for quick evaluation and demonstration. Additional Information about the Sensor Tag set is located at www.ti.com/lprf-stdroid-pr-eu.
The Sensor Tag kit does not require any software or hardware to quickly launch Bluetooth Smart apps on your smartphone or tablet. Developers share their progress using Sensor Tag on the Texas Wiki page ( http://processors.wiki.ti.com/index.php/Bluetooth_SensorTag?DCMP=lprf-stdroid-eu&HQS=lprf-stdroid-pr-wiki1-eu) and on Twitter using the hashtag #SensorTag.
Six built-in Sensor Tag sensors, including non-contact infrared temperature sensor TMP006 from TI are helping to develop numerous applications in areas such as healthcare and education, as well as create new accessories for mobile devices. The kit works with TI's free, over-the-air updateable BLE-Stack TM software. The CC2541-based Sensor Tag complements TI's other CC2564-based dual-mode Bluetooth and WiLink TM solutions.
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