CH616509A5 - Electronic maximum-demand meter - Google Patents

Description

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PATENT CLAIMS

1. Electronic maximum counter, consisting of a kilowatt-hour meter and a maximum unit, characterized in that the maximum unit has a microcomputer with integrated memories for evaluating the information on energy consumption offered in pulses, the microcomputer being controlled via external coding plugs and the instantaneous and monthly maxima are output digitally and / or analogously for a display and data storage device, and that the microcomputer receives a signal in the event of a power failure, which is triggered by the mains voltage dropping below a defined value and causes the numerical and logic state values in before the supply voltage collapses the non-volatile memory is transferred.

2. Maximum counter according to claim 1, characterized in that an external memory for changing program parts is provided, which allows a program change without exchanging the microcomputer.

3. Maximum counter according to claim 1, characterized in that the length of the measuring period and, in the case of automatic resetting, the length of a resetting period is calculated from an externally supplied reference frequency.

4. Maximum counter according to claim 1, characterized in that it is designed for use in a network with ripple control, and that the maximum work decodes the switching commands from the ripple control pulses.

The use of maximum counters by small consumers of electrical energy is opposed by the relatively high price of the conventional mechanical devices, which is due to the large amount of manual production and adjustment work. Electronic components are particularly suitable for reducing this effort and thus for creating an economic maximum counter, according to the object on which the present invention is based, whereby a required long-term reliability with simultaneous economical production of an electronic maximum counter can only be achieved if the number of components is kept small can.

This object is achieved by the invention as defined in the characterizing part of patent claim 1.

Advantageous embodiments of the maximum counter according to the invention are specified in claims 2 to 4.

In the case of electronic maximum meters, there is a requirement that the numerical value of the highest monthly maximum accumulated up to that point must be saved in the event of a power failure. In addition, certain states of the control logic must be saved in order to ensure that the maximum work runs from the point of interruption when the mains voltage returns. This is particularly important if the maximum work was interrupted by a power failure during the monthly transfer of the maximum to the mechanical cumulative counter in order to prevent the transfer of incorrect values. For the transfer of e.g. Max. 4-digit numbers («9999») from the electronic monthly memory into the cumulative counter are at step speeds of e.g. 10 ... 20 Hz times of several minutes, so that a power failure can also occur during a transfer. In principle, electronic memories and display devices can also be used for the conventional cumulative counter, but currently neither electronic memories nor display elements have a reliability comparable to that of the mechanical counter.

Electronic non-volatile memories are known. Such memories, which are stored in a special programming device, i.e. not in the actual circuit. Non-volatile memories that can be operated like freely addressable memories in the circuit itself are currently. still relatively unreliable. Known memories of this type have the property that the number of write cycles is limited. It is not possible to operate such a circuit as a normal memory because the number of usable write cycles would be reached quickly. A write command may only be given if the storage property is actually required in the event of a power failure. To do this, a power failure must be recognized in good time so that all the values to be stored are transferred to the non-volatile memory until the electronics supply voltage collapses. According to the current state of technology, it is possible to integrate such a non-volatile memory together with other metal oxide transistors on the same chip.

Two basic versions of an electronic maximum counter are possible:

1. A customer-specific large circuit with a maximum work in conventional digital technology and

2. the use of a microcomputer.

Here, the entire circuit can be integrated on a chip; however, a multi-chip system can also be used.

Favorable solutions are: a single-chip microcomputer with non-volatile memory integrated on the chip that can be changed electrically, or a non-volatile, integrated memory that is set in a special programming device, or a single-chip microcomputer with external non-volatile Memory for the values to be saved during a power failure.

The following description refers to the version with a microcomputer, which is more economical compared to the customer-specific large circuit, since only a mask change of its program memory is required for a customer-specific adaptation of the microcomputer.

The electronic maximum work is e.g. Information on energy consumption is supplied from outside, e.g. in the form of rotor disk pulses from the assigned electricity meter, a pulse constant as an adaptation factor of the recorded pulses for identifying the energy consumption, a measurement period specification and the mains frequency for controlling the measurement period. For the measurement period specification, a time base device can be provided in the maximum counter, which for example counts mains frequency pulses, which then form a measure for the duration of the measurement period and are fed to a target counter for comparative evaluation. As further information, tariff changeover commands, switch-on and switch-off commands, monthly reset commands and power failure signals can be supplied to the electronic maximum work.

The tariff switch commands and the switch-on and switch-off commands can be combined, so that an input of the maximum work is omitted or becomes free. The monthly reset command is e.g. given by a ripple control receiver or programmed within the device for a predetermined fixed time. Manual reset can also be provided.

With a maximum counter, the numerical value of the monthly maximum and certain status signals of the logic or the program sequence in the event of a power failure must be saved.

In order to trigger the storage in the non-volatile memory, the Maximumwerk must be informed of an impending mains voltage failure. When the power returns, the same signal causes the computer to resume its program at a predetermined point, reading out the values contained in the non-volatile memory, transferring them to its working memory and further processing.

The above-mentioned programming must be able to be changed customer-specifically. There are several ways to do this:

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a. In the case of a computer, the command memory of which is preferably also designed as a non-volatile memory, the entire command memory is set for each device in the test field from a suitable data carrier (e.g. punched tape), with all customer requests being programmed.

b. In the case of a computer with a mask-programmable instruction memory, the program is executed in such a way that the computer requests external encodings in the form of diode or jumper read-only memories at its inputs, which are then changed in a customer-specific manner.

c. For a computer with a separate instruction memory, i.e. in which the command memory is not integrated, the entire command memory can be replaced in a customer-oriented manner.

Depending on the number of maximum tariffs, the maximum work output the instantaneous and monthly maxima in the form of digital or analog numerical values for display and / or data output.

Furthermore, control signals for reset counters and cumulative counters as well as for display elements can be output at several maximum tariffs.

When using a single-chip microcomputer, this is preferably operated by upstream multiplexing devices due to the small number of inputs. The external command input is thus controlled via one or more multiplexers. Fixed programs, e.g. the measuring period length, pulse constant, monthly reset command for automatic reset after a preselected time etc. communicated to the microcomputer via coding plug.

The number of available outputs, on the other hand, is almost always sufficient, so that you can assign your own outputs to the cumulative counter, the reset counter, the display elements for the instantaneous and monthly maximum, etc.

Another advantage of using microcomputers of the type mentioned is the simple programming of several maximum tariffs, since the freely programmable data memory integrated in the microcomputer always has a much larger one

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Has storage capacity than is required for a tariff; only 16 bits in the working memory and in the non-volatile memory are required for each additional monthly maximum.

Instead of an integrated, complete program memory (ROM) of the one-chip microcomputer, an external memory can also be used, by means of which the program can be changed without exchanging the one-chip microcomputer. Certain parts of the program are stored in an additional external circuit, e.g. non-changeable read-only memory (ROM) i "written. Thus, for example in the case of a wire-bridge read-only memory, no change in the mask of the program memory of the one-chip microcomputer is required.

Furthermore, for extremely economical maximum counters, external memories can be omitted: after a mains i5 failure, when the mains voltage returns, the microcomputer continues from a predetermined program point and all memories are set to zero.

Since the maximum counter normally still requires a ripple control receiver, it makes sense to use the already existing computer, which can take over the calculation of the ripple control commands according to the customer-specific program. It is then only necessary to filter out the ripple control pulses from the network and offer them to the computer in the form of flawless digital signals; the entire decoding of the commands normally required can then be omitted.

Digital displays can be used to display the instantaneous and monthly maxima, whereby a single display with surrounding can be used, or qua-mi sianalogue displays in the form of bars made of light diodes, liquid crystal segments etc. can be used, since these displays have a low resolution and accuracy are sufficient. Conventional pointer instruments can also be used; it is economical to take the current for these instru- ments without a digital / analog converter directly from the computer in the form of a duty cycle modulated pulse series of any frequency.

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