IE61640B1 - Timeswitches - Google Patents

Description

In existing domestic electricity supply systems the consumer is provided with a two-rate meter which has a first dial indicating the number of day-time (expensive) units consumed and a second dial indicating the number of night-time (cheap) units. In one known system, the meter is switched over from one rate to the other by means of a tariff time switch. This is typically arranged to switch on to cheap rate at 12.00 midnight GMT and back to the full rate at 7 am. GMT, no *5 account being taken of BST.

In another known system, the meter is switched over by a radio time switch, actuated by radio signals transmitted by the SSC in accordance with the wishes of 2θ the local electricity supply authorities. Where the signals are transmitted at midnight and 7 am. GMT throughout the year, this is equivalent to the tariff time switch system described in the preceding paragraph and no particulr problems arise. However, some local electricity supply authorities have the timing of the radio signals changed along with British Summer Time i.e. to 11 pm and 6 am GMT. This means that there is then a discrepancy with any other timers in the consumer's supply system which still keep GMT, for 30 example water heater controllers or night-storage ·> heater timeswitches. Where such a device is set to switch off at 7 am and maintains GMT throughout the < summer, there will be a period of one hour at which electricity will be supplied at the higher instead of ths lower rate. The present invention seeks to overcome this problem.

According to the present invention there is provided a, timeswitch comprising internal clock means, a first switch means having at least two positions, and a second switch means, wherein, with the first switch means in a first position, actuation of the second switch means has no effect on the internal clock means, and with the first switch means in a second position, successive actuations of the second switch means alternatively ' produce backward and forward shifts of substantially one hour of the internal clock means.

The timeswitch may also comprise a time display which is changed by substantially one hour· toy actuation of the second switch means, whether the first switch means is in the first or second position.

The first switch means may have a third position in which a battery contained in the timeswitch is disconnected.

The first switch means, e.g. a three-position slider switch, is intended to be set on installation and is preferably located at the rear of or inside the housing of the timeswitch, whereas the second switch means, e.g. a push-button, is intended for operation by the consumer and is preferably located at the front of the housing for operation at the changeovers each year between GMT and BST.

A preferred embodiment of the present invention will now be described, by wav of principle only, with reference to the accompanying drawings, of which: Fig 1 is a schematic diagram of a domestic electricity supply system; Fig 2 is a timing diagram of which line A represents GMT; Fig 3a and 3b are schematic views of the front and rear respectively of a timeswitch in accordance with the present invention? and Fig 4 is a circuit diagram of part of the circuitry of the timeswitch of Fig 3.

Referring to Fig 1, there is shown a domestic electricity meter 10 with a day-time unit display 11 which is active, say from 7am to midnight, and a cheap rate unit display 12 which is active for the rest of the time. The meter 10 is switched from one rate to the other by a tariff time switch (TTS) 20 installed by the local electricity supply authority. Time switch 20 is set to GMT and is so maintained throughout the year, see line B of Fig 2. Providing any other timeswitches present in the system are also set to GMT, no problems arise.

As an alternative to timeswitch 20, the local electricity supply authority may supply a radio timeswitch (RTS) 30, which is activated by specially coded radio signals transmitted by the British Broadcasting Corporation. There are two current RTS schemes in operation. In the first, BST is ignored and the radio signals are broadcast at the-same time in GMT throughout the year. (This corresponds to the TTS alternative set out in the previous paragraph*, see line S of Fig 2.) In the second scheme*, however*, the signals are broadcast at the same local time, that is at midnight GMT and am GMT during the winter and at midnight BST and 7am BST during the summer, line D of Fig 2- This means that water heater controllers, or any other electrical devices in the system,with time 1C switches which are permanently set to GMT, see line C of Fig 2, will be out of synchronism with the rest of the system throughout the summer months. Thus, if the timeswitch is set to 2am to 7am, there will be a period of time during the morning of one hour (7am to 8am) in which the device will consume electricity at the higher rate rather than the lower rate. Another disadvantage may arise in that the consumer may require piping hot water at 7am, whereas heating may not be completed until after this time.

Fig 3 to 4 show a time switch 50 in accordance with the present invention. The front surface 51 of the housing includes an LCD display element 52 which.is backilluminated by LED's 53, Fig 4. The display element comprises a first portion 55 indicating time-of-dav and a second portion 57 indicating summer or winter. A push button 56 is provided for switching over from GMT to BST and vice versa.

The rear surface 61of the housing has a three-position slider switch 62 which is movable between OFF, BST/GMT, and GMT ONLY positions. The OFF position is a so-called commissioning position during which a non-rechargafale stand-by battery 70, Fig 4, of the timeswitch is disconnected until the time switch is installed. This serves to prolong the working life of the battery.

In the BST/GMT position of switch 52, actuation of the push-button 56 shifts the time of an internal clock within integrated circuit 80 by one hour. Alternate actuations of button 55 produce backward and forward shifts, so that at the beginning of British Summer Time the time is moved forward one hour and at the end of BST back one hour. The time shown by display portion 55 is also changed by one hour, and display portion 57 switches over. Push button 56 is operated twice a year by tho consumer when the other clocks in the building are reset.

In the GMT ONLY position of switch 62, actuation of button 55 has no effect on the internal clock, but display portion 55 is shifted by one hour so that it continues to indicate the correct local time.

Cn installing the time switch 50, the switch 52 is set in accordance with the scheme operated by the local electricity supply authority. If it employs radio signals transmitted at the same local time throughout the year, switch 62 is moved to the BST/GMT position. Thus the timeswitch has the advantage of removing timing discrepancies in such systems between the authority's and the consumer's time switches. If the authority employs radio signals transmitted at GMT throughout the year, or tariff time switches, switch 52 is moved to its GMT ONLY position. Thus the timeswitch has the advantage that it can be used whatever scheme is employed by the local electricity supply authority.

Parts of the preferred circuit for timeswitch 50 are shown in Fig 4. Switch 52 comprises ganged sliding contacts 63 and 64. In the OFF position, battery 70 is disconnected from the rest of the circuit to prolong its life. In the other two positions of switch 62, contact 63 connects the battery to the rest of the circuit. In the BST/GMT position, sliding contact 64 connects lines 67 and 68 which controls logic circuitry in the i.e. 80 to shift the time of the internal clock by one hour when button 56 is pressed, and to alter display 52 correspondingly. In the GMT ONLY position, lines 67 and 68 are disconnected which controls the logic circuitry so that actuation of button 56 has no effect on the internal clock but only alters display 1C 52. The logic circuitry is configured so that actuation of button 56 produces alternate backward and forward shifts of one hour.

Various modifications may be made to the above15 described arrangement. For example, display 52 may be omitted, or may be limited to portion 55 or portion 57 above. The OFF position of switch 62 may be omitted if desired. Indeed the GMT ONLY position may also be omitted where it is known that BS T/GMT switching is definitely required. If both OFF and GMT ONLY positions are to be omitted, switch 62 may be completely omitted and the necessary logic circuitry may be permanently connected. In certain applications battery 70 may be rechargable.

The timeswitch may be used in a water heater controller. It may alternatively be used in a timer connected between a ring main and a night storage heater. At present night storage heaters are connected by dedicated wiring via a distributing board to an 80amp circuit controlled, for example, by a tariff time switch·. The present invention provides a convenient way of adding one or more night storage heaters to an existing system without the considerable expense of extra dedicated wiring all the way back to the distributing board. Instead, provided the power is below 3kw (or in some cases 4kw) „ one or more tappings may be taken from the normal ring main, with timeswitches according to the present invention provided between the ring main and the extra night S storage heaters»

Claims (10)

1. ciaiss

1. A timeswitch comprising internal clock means, a first switch means having at least two positions, and a second switch means, wherein, with the first switch means in a first position, actuation of the second switch means has no effect on the internal clock means, and with the first switch means in a second position successive actuations of the second switch means alternatively produce backward and forward shifts of substantially one hour of the internal clock means.

2. A timeswitch according to claim 1, further comprising a time display which is changed by substantially one hour by actuation of the second switch means, whether the first switch.means is in the first or second position.

3. A timeswitch according to claim 1 or 2, wherein the first switch means has a third position in which a battery contained in the timeswitch is disconnected.

4. A timeswitch according to any preceding claim and further comprising a housing, wherein the first switch means is mounted at a relativelv-inaccessible position and the second switch means is mounted at a relatively accessible position.

5. A timeswitch according to claim 4, wherein. the first switch means is mounted at the rear of the housing.

6. A timeswitch according to claim 4, wherein the first switch means is mounted inside the housing.

7. A timeswitch according to any of claims 4 to 6, wherein the second switch means is mounted at the front of the housing.

8. A timeswitch substantially as herein described with reference to Figures 3 and 4 of the accompanying drawings.

9. A water heater controller comprising a timeswitch according to any preceding claim.

10. A night storage heater system comprising a timeswitch according to any of claims 1 to 10.