BS 7647:1993 download.Specification for Radio teleswitches for tariff and load control.
Radio teleswitches are components of a system of remote control permitting the operation of a large number of load switchings from a central point. The signals used for this purpose are superimposed upon the 198 kHz national broadcast transmissions, and when decoded by the radio teleswitch will cause a relevant output switch to change state either immediately or at a specified time. Thus electrical power circuits and/or meter registers may be energized or de-energized as required.
Details of the radio teleswitch specified in BS 7647 have been agreed between electricity supply companies and manufacturers. Full details of the message codes and specific security criteria are under the control of the Electricity Association. Those parties requiring such details, available under licence, should contact:
The Electricity Association
30 Millbank
London
SWIP 4RD
1 Scope
BS 7647 specifies requirements and the type tests of radio teleswitches that are intended for mounting in those locations in domestic, industrial or commercial premises where electricity meters, tariff and load control timeswitches or ripple control receivers are mounted.
BS 7647 covers radio teleswitches which control two load circuits, i.e. space heating and water heating, and two tariff circuits.
Certain details of the message formats, e.g. “Start time’1 and “On period” codes, are not specified in BS 7647 and prospective manufacturers are advised that compliance with these details is also necessary.
BS 7647 does not extend to receivers that are intended for use in street lighting or traffic signs.
NOTE The units employed in this standard are those specified in BS 5775.
2 References
2,1 Normative references
BS 7647 incorporates, by reference, provisions from specific editions of other publications. These normative references are cited at the appropriate points in the text and the publications are listed on page 32. Subsequent amendments to, or revisions of, any of these publications apply to BS 7647 only when incorporated in it by updating or revision.
3.1.8
rated supply frequency (f)
value of the supply frequency for which the radio teleswitch is designed
3.2 Functional elements
3.2.1
aerial
element which receives the 198 kHz signals
3.2.2
code
the sequence of a given number of code words, check words, binary numbers and binary address values
3.2.3
decoding element
element which identifies from the signals received the corresponding commands for which it is configured and sends appropriate information to the output element directly or via the programme
3.2.4
programme
the information held by the radio teleswitch which determines the sequence of operation of the output element
3.2.5
stored programme
programme, held in memory, in operation at a particular time, derived from the broadcast programme or the failback programme
3.2.6
broadcast programme
programme which provides, updates or refreshes the stored programme derived from the signals received as decoded by the decoding element
3.2.7
faliback programme
programme, held in non-volatile memory, which provides the stored programme or replaces it when the stored programme is not saved upon interruption of supply
3.2.8
non-volatile memory
storage device which can retain information in the absence of power
3.2.9
output element
element comprising one or more switches controlled by information provided by the decoding element
4 Electrical values
4.1 Rated supply voltage (Un)
The rated voltage, U, shall be the nominal UK supply voltage, i.e. 240 V.
4.2 Rated supply frequency f)
The rated supply frequency, f, shall be the nominal
UK supply frequency, i.e. 50 Hz.
5 Mechanical properties
5.1 General
Radio teleswitches shall be designed and constructed in such a way as to avoid introducing any danger in their use and under the conditions for which they are intended, so as to ensure the following:
— personal safety against electric shock;
— personal safety against effects of excessive
temperature:
— prevention of spread of fire;
— protection against penetration of solid objects,
dust or water.
All parts which are subject to corrosion shall be effectively protected. Any protective coating shall not be liable to damage by handling or damage due to exposure to air.
When tested in accordance with 10.2.3. components and wiring shall remain fastened and secured against loosening.
5.2 Radio teleswitch case
The radio teleswitch shall have a case which can be sealed in such a way that the internal parts of the radio teleswitch are accessible only after breaking the seal or seals.
The cover shall not be removable without the aid of a tool.
The case shall be so constructed and arranged that any non-permanent deformation cannot prevent the satisfactory operation of the radio teleswitch.
5.3 Terminals and terminal blocks Terminals shall be grouped in a terminal block(s).
NOTE 1 When choosing insulating materials for the terminal block(s), testing of materials should be taken into account to ensure adequate insulating properties and mechanical strength.
The holes in the insulating material which form an extension of the terminal holes shall be of sufficient size to accommodate also the insulation of the conductors.
8.2 Message format
The message format shall be as shown in Figure 4 and shall consist of a 32 bit user message within each 50 bit message broadcast (excluding time messages, see Figure A.10).
The radio teleswitch shall respond to two types of message as follows and shall also decode time (UTC), see 8.7.
a) Command messages. These enable a user to send instructions to up to two groups of radio teleswitches, requesting each of up to four switches within the radio teleswitch to assume immediately the required status.
The first bit is set to 0 to indicate that a command message follows. The function code is 000 for radio teleswitches. Function codes 001 to 111 are reserved for future use. Figure 4a) indicates the command message structure.
b) Programme messages. These enable a user to amend or refresh a programme stored within the radio teleswitch. For each switch up to four blocks may be set defining periods for which the switch will be on. Each active block defines a bstart time” (in UTC) and an “on period”. There is no restriction on the “start time”, and “on periods” may be separate, adjoining or overlapping (see Figure 5). Start times are subject to 7.5 mm resolution and on periods are given in multiples of 15 mm with a maximum of 8 h.
The first user bit is set to I to indicate that a programme message follows. Figure 4b) indicates the programme message structure.
8.3 Control of output element
8.3.1 Normal mode of operation
Switches shall be operated in the following circumstances:
a) when a command message is received requiring a change in status;
b) according to the stored programme as refreshed or updated by programme messages. unless a command message is received requiring a change in status.
NOTE 1 The stored programme may. at the manufacturer’s discretion, be supported by a non volatile memory to retain time and programme information for indefinite periods in the event of supply voltage interruption.
NOTE 2 After the initiation of any switching operation, the radio teleswitch need not respond to any radio 8ignals for whatever purpose (e.g. command, programme. time) for a period not exceeding 12 s.