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Radio teleswitch

The radio teleswitch is a device which lets electricity suppliers switch large numbers of electricity meters between different tariff rates.

We have overall responsibility for the operation and maintenance of the central radio teleswitch system in the UK on behalf of the electricity suppliers.

  • History

    Radio Teleswitching is the transmission of digital data on radio for alarm, control and information to locations throughout the reception area of the radio transmissions.

    The idea of using existing national broadcasting infrastructure for sending teleswitching signals was considered back in 1964 and was originally primarily intended for load management, to enable the switching on of large numbers of night storage heaters and water heaters to be staggered to avoid sudden large increases in load as night rate systems cut in. More recently, it has been developed as a tariffing system.

    There are thought to be around 800,000 RTS equipped meters in the field. However, the idea had to wait for technology to catch up with it and when this happened over a decade later, Radio Teleswitching began to emerge as a practical proposition. Following the successful conclusion of extensive trials which started in 1979, the relevant authorities approved Radio Teleswitching transmissions on the BBC’s national 198 kHz frequency radio broadcasts.

    An important condition of the approval was that the radio teleswitching data should not impair the reception of BBC Radio 4 news and entertainment programmes normally transmitted on that long wave frequency. This was adequately demonstrated in the trials.

    Fully operational Radio Teleswitching facilities became available in 1984. By being first in establishing Radio Teleswitching on a national scale as a fully operational, cost effective communication system for use in energy management, the electricity industry gave the UK a world lead in this field. The technique won the Queen’s Award for Technology.

    The industry holds a patent on the development and issues licences to approved manufacturers of Radio Teleswitch receiver controllers. The devices are normally simple, competitive in price, highly reliable and capable of being locally or remotely controlled.

    A unique feature and advantage of Radio Teleswitching is its ability to give authorised users instant, low cost access to a proven, nationwide, broadcast communication facility through nothing more than a PC and a modem. Users do not have all the problems associated with selecting, owning and operating complex communications infrastructures.

    The flexibility of the system allows a range of load management, demand side management and other control strategies to be deployed. Load management applications have included the matching and co-ordination of generation and plant loading with customer demand for smaller isolated power systems.

    For larger, more complex systems, it permits a wider selection of tariffs with more dynamic control for influencing energy consumption patterns and system loadings more precisely. This can make it easier to optimise economic margins, defer capital investment and accommodate operational constraints.

    In recognition of both the technical innovation and the potential economic benefit it could bring the system received the Queen’s Award for Technological Achievement in 1987.

  • Technical specifications

    The system basically comprises user terminals and modems, the central teleswitch control unit (CTCU) the LF Data System, the 198kHz BBC Radio Four transmission system and radio teleswitching receiver controllers (RCs).

    Each user of the system, the electricity distribution networks operators and electricity transmission network operator has a unique set of codes enabling them to address only their own block of meters and switches.

    These instructions are sent by the network operators to the Central Teleswitch Control Unit (CTCU) housed and maintained by Cygnet Solutions.

    The CTCU processes and forwards their switching codes to the BBC Message Assembler at Crystal Palace.

    Here, the electricity industry codes are combined with the instructions from other users of the service and sent to the three national networks of transmitters. The main transmitter at Droitwich (see also the BBC site), rated at 500kW, can reach most parts of the UK and some parts of continental Europe while the two smaller transmitters located at Westerglen and Burghead cover Scotland and Northern Ireland.

    Messages are encoded onto the Amplitude Modulated (AM) Radio 4 signal using Phase Shift Keying (PSK) techniques.

    30 messages are transmitted per minute, each message having 50 bits of data. 18 of these bits are taken up by a BBC header and Cyclic Redundancy Check (CRC) tail. 32 bits are available for data.

    The RadioTeleswitch specification (BS7647) lays down specific formats for its user message contents. Two message types are defined:

    • command (or immediate) which has priority of broadcast, and on receipt immediately sets a Teleswitch (RCs) internal switches to required status, overriding any programmed status;
    • programme, which updates or refreshes the operating program stored within a Teleswitch (i.e. internal switches will not change status until required by the program).

    An ‘immediate’ instruction can take one or two minutes from initiation of a request at the terminal of a user, depending on other traffic on the data system, and is intended to allow fast, broadcast load shedding.

    The system’s ability to offer users both programmed and immediate broadcast control have enabled companies using the system to provide weather-related control of electricity storage heaters in specialised arrangements such as ‘budget warmth’ and ‘heat with rent’ schemes.

    The transmission of cost reflective messages and weather forecast information has allowed the concept of controlled consumption to be extended to provide more comprehensive forms of premium heating and other services. The ability to influence demand patterns more finely so that they respond more immediately to changes in supply cost, is to the advantage of both suppliers and customers. It gives customers another form of choice.


  • Features

    ‘Simple Teleswitch’

    • Teleswitch replaces clock in Economy 7 systems
    • Two modes:
      • Peak rate power (storage heaters off)
      • Off-peak power (storage heaters on)
    • Cannot vary heating load time without varying peak/off-peak times

    ‘Double’ Teleswitch

    • Twin teleswitch and meters
    • Heating load is independent of tariff changes
    • Able to offer:
      • X hours of heating per day
      • Fixed peak/off-peak times

  • What to do if there is a problem with your teleswitch

    If you have any issues or problems with the teleswitch installed in your home or business you should contact your electricity supplier. You can find out who your supplier is by contacting your electricity network operator.

  • Current status

    Radio teleswitches are being replaced as part of the smart meter rollout programme.To enable the programme to continue the life of the radio teleswitching system has been extended through to March 2025.


    If you have any questions about your radio teleswitch or getting it upgraded to a smart meter please contact your electricity supplier. You can find out who your supplier is by contacting your electricity network operator.

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