GB2264566A - Electric energy cost monitor - Google Patents

Abstract

An electric energy cost monitor (3) includes means to determine the amount of energy being used, a keyboard (4) to enter a tariff per unit of energy and a display (2) to display the total cost of the energy which has been used. In use, the monitor (3) is connected to an appliance or plant to be monitored (not illustrated in Figure 1) and during the period of operation the monitor measures the voltage and current, and these values together with the entered tariff value and the time are processed by a microprocessor to determine the cost of running the appliance or plant; this is displayed (2) as a monetary value. <IMAGE>

Description

ELECTRICAL ENERGY COST MONITOR The present invention relates to an apparatus for the monitoring of the amount and cost of electrical energy used by a consumer thereof, given in the form of a direct reading.

At present energy used is monitored by the consumer reading the digits of a calibrated metering system. This method gives the consumer a record of the uits of energy consumed in kilowatt hours. To enable the consumer to define the amount of energy used in terms of cost, the units of energy used must be multiplied by a tariff value set by a supplier of the energy.

According to the present invention there is provided an apparatus for monitoring the amount and cost of electrical energy, the apparatus comprising first means to determine continuously the amount of energy being used, second means to signal an appropriate tariff per unit of energy at the time, means responsive to outputs of said first and second means to calculate the cost of energy being used and means to store and to display total cost of the energy which has been used. This enables a consumer to monitor the use of energy in terms of cost, instead of units.

This invention relates particularly to 'low and medium pressure' supplies - supplies using 0 - 415 volts at a maximum current rating of 200 ampere.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: FIGURE 1 shows an apparatus embodying the invention in conjunction with a standard domestic power supply; FIGURE 2 shows the apparatus in use in conjunction with an industrial supply; FIGURE 3 is a perspective view of an apparatus embodying the invention; FIGURE 4 is a schematic drawing to show that remote readings may be taken from the apparatus; FIGURE 5 shows diagrammatically a possible commercial use of the apparatus; and FIGURE 6 also shows a commercial or industrial application of the apparatus.

The apparatus is constructed as a self-contained 'stand alone' unit 3. All the components are housed in a robust enclosure designed to meet all electrical safety standards. The apparatus uses the supplied voltage to operate its electronics. The consumer simply inputs the tariff value and any other information via a keypad using a coded password. The value of the energy consumed can be stored by the apparatus and linked as indicated in Figure 4 via communications to remote sites for use in other calculations or billing. A direct printout is also possible. The consumer is able to read the direct cost of the amount of energy used from the continuous display.

In factories or commercial premises the direct cost value of the energy used by machines or appliances can be seen at an instant. This means that the future bill can be predicted, or the direct cost of producing an item on a machine can be seen, helping production staff to cost more effectively. The apparatus has the ability to display an average cost as well as the peak cost. This allows the consumer to plan future use of energy and also reduce costs by economising on energy usage. This has the additional benefit of helping the environment.

Although calibrated the apparatus is not designed to replace the calibrated meter supplied by area boards or other electricity supply organisations.

The apparatus is contained within an enclosure made from ABS or other such material. An lcd alphanumeric display unit 2 and a user keyboard 4, again alphanumeric, are provided. Additional buttons to access and store information may also be provided. A connection cable to a current clamp are used on the hand-held portable unit. The tariff charge is entered into the software via the keypad 4, after an access code has been entered. The tariff charge is then stored in memory. Using the current clamp as seen on the portable example the current is then measured. Having already connected the supply voltage used by the appliance to the apparatus the energy used (watts) can be calculated. This value is then multiplied by the tariff factor and time to give the value shown in display 2.

Figure 1 shows the concept of the apparatus in the form of a system block diagram.

The user connects the appliance to the apparatus and enters the data relating to tariff charges, date and time of day via the keypad. The current and voltages are measured using either a current clamp and voltage reduction circuit or voltage and current reduction circuit.

The apparatus may include a single phase measuring unit and a three phase measuring unit.

Having sensed the current together with a voltage measurement, the next stage conditions the signals before passing them to the analogue processing and interface circuit. The analogue signals are multiplied using an analogue multiplier. The product of the analogue multiplier is then entered into the microprocessor circuit, via the interface bus. The microprocessor stores this information in a register stack.

The original information about tariff charges entered into memory via the keypad and stored on an eeprom is then processed together with the time by the microprocessor.

This information in ASCII format is set to the lcd display and control circuit. The display 2 then shows the present time of day, the date, the actual cost of units used to present. The total cost of units used over a period of time, the average value and the peak value date, and time.

The display can also show the kilowatt hour.

All these formats are accessed via the keypad.

The communication circuit can send and receive information from a host computer or printer.

Figure 1 shows an example of a domestic installation using the apparatus.

The apparatus is connected in the supply line after the main fuse and meter. The single phase unit can also be fitted with plugs and sockets, for easy and quick testing of appliances.

Figure 2 shows an example of the apparatus connected to a process machine 1.

The apparatus 3 is connected in the 3-phase supply line after the main fused isolator 14. The control cabinet connected to the machine is shown 12.

The apparatus can be fitted with 3-phase plugs and sockets to allow easy and temporary evaluation of machine running costs.

When connected to a 3-phase network all three phases are fused and phase angle measurement taken.

When used in a domestic application, the unit would enable the householder to evaluate their electrical energy consumption in direct financial terms.

Two models may be available to the domestic market. The first model would take the form of a portable unit to enable the measurement of single electrical appliances around the household. This would enable the household to define the cost of running a particular appliance.

The second model would be a fixed unit fitted to a position within the location of the present electrical consumer units. This type of unit would measure the complete electrical energy consumed by the particular household. It would also estimate the future bills given data on a daily basis.

In future the fixed unit would communicate directly with the supplier of electrical energy, enabling them to read the meter without physically having to send someone to look at the meter.

In an industrial application the unit would be used to monitor the cost of production processes at a programmed rate (i.e. per hour).

Production engineers could then use this information to determine the direct cost of producing a component on a particular machine. The information could also be used to monitor the efficiency of both process and machine.

These units are able to communicate directly with a computer located in a central production control centre.

Finally the information could be stored for future analysis and production planning.

The unit could either be fixed or portable.

This is an invaluable aid to both the small one-man machine shop and to the big multi-national companies, enabling them to define the exact unit cost of a product.

A commercial unit would take the form of a fixed unit located in various departments.

It would be capable of measuring lighter loads than the industrial unit (mainly lighting etc).

In the hotel business it would monitor single rooms to give a costing of customer usage per room at the end of a stay. This would enable the hotel to pass on direct energy usage to the customer.

It could also be used in multi-roomed rented accommodation to again pass on the direct cost of energy use to the tenant.

Claims (5)

1. An apparatus for monitoring the amount and cost of electrical energy, the apparatus comprising first means to determine continuously the amount of energy being used, second means to signal an appropriate tariff per unit of energy at the time, means responsive to outputs of said first and second means to calculate the cost of energy being used and means to store and to display total cost of the energy which has been used.

2. An apparatus as claimed in Claim 1, further comprising clock means and wherein the second means is able to signal one or more tariffs dependent on the time indicated by the clock means.

3. An apparatus as claimed in either Claim 1 or Claim 2, further comprising means to transmit the total cost to a remote location.

4. An apparatus as claimed in any one of the preceding claims, further comprising an additional source of power to maintain any stored information and display when the energy being measured is not supplied.

5. An apparatus for monitoring the amount and cost of electrical energy substantially as described herein with reference to the accompanying drawings.