DE102007044166A1 - Current production and usage quantity measuring arrangement for low voltage grid, has interface for bidirectional data exchange with external data acquiring and evaluating unit e.g. personal computer - Google Patents

Abstract

The arrangement has a measuring unit (4) installed before and/or after a junction point (1) at a conductor (2) of an electric circuit (3). A contact-less transformer measures current flow, and a measuring signal converter e.g. analog to digital converter, is in connection with a measuring device (7a) for producing a digitized measuring signal. An interface e.g. RS 232, RS 422and USBinterfaces, is provided for bidirectional data exchange with an external data acquiring and evaluating unit (9) e.g. personal computer. An independent claim is also included for a method for operating an arrangement of measuring current production and usage quantity in a low voltage grid.

Description

The The invention relates to an arrangement for measuring current yield and / or consumption variables in one Low-voltage network according to the preamble of claim 1.

Low voltage networks become dependent from the particular application with single-phase or three-phase voltages in the range of 230 V or 400 V up to an upper limit of 1000 V operated. They are usually used to supply end consumers and are trained in different ways. Low voltage networks usually start at a transformer station in the immediate vicinity near Residential or commercial areas in which the tension of the supraregional High-voltage networks of 10 kV or 20 kV for a three-phase system with one Phase voltage of 230 V against a grounded star point and a Phase voltage 400 V between each two outer conductors are transformed.

special shapes Such networks are low voltage industrial networks with a voltage of 400 V, 500 V or 700 V, or large-scale networks connected to a medium-voltage network are connected and over have their own transformer, which feeds into the internal low-voltage grid. Low voltage networks will also be used for messaging, in particular for transmission so-called ripple control signals or in some countries for transmis tion higher-frequency Data signals by means of a carrier frequency modem used.

About distribution points The low voltage network branches into smaller subnets, which constitute the consumer power supply in the narrower sense. Examples therefor are the power supplies in a residential building. Within the subnet There are other sub-distributors, especially on risers connected floor distributors, distributors for closed sub-areas, in particular apartments or other room complexes.

A Measurement of consumption variables in such Subnets usually take place by electrically connected three-phase current meters connected in the sub-networks (see above) called Ferraris counter). These are at convenient points, e.g. in a control cabinet of a house, and lead for individual tenants, apartments and the like units a consumption measurement. A consumption measurement with such a device for even smaller areas worthwhile because of the associated effort not and is usually not executed.

consumption measurements for individual Consumers, i. For individual power connections and sockets, are possible with so-called energy cost meters. In dependence of their embodiment These are either connected to a power connection, i. into a socket, plugged in, or by means of current clamps for a certain time to individual Cables connected.

such solutions by no means satisfy. It can only short-term measurements an extraction point or a distributor. A correct determination and presentation of electricity consumption on the Level of the respective subnet or even a record of the Consumption over a longer one Period are impossible. Energy monitoring devices, which can be plugged into sockets and certain memory functions for measured values may have only for each provided with a socket and can for the calculation or for Tracking power consumption in any subnetwork not to be used with multiple consumers.

such Devices are also not useful when a power yield of a local power source in the low voltage network, such as a generator o of a solar system in or on a building, measured or over a longer Period should be tracked.

Out the disadvantages and problems mentioned results in the invention underlying task, an arrangement for measuring electricity yield and / or consumption data in a low-voltage network, with the principle of any Levels, sub-areas, consumption points or feed-in points of the low-voltage network Consumption sizes and / or Electricity yields on simple, inexpensive and can be measured continuously. A long-term pursuit of these sizes possible be.

The Task is with an arrangement for the measurement of electricity yield and / or consumption data solved in a low voltage network. The inventive arrangement is characterized by at least one before and / or after a distribution point of the Low voltage network installed on a line of a circuit Measuring unit off. This includes a contactless current transformer for Detecting a current flow and an internal measuring signal converter in conjunction with a detection device with a measured value memory and an interface for a bidirectional data exchange with an external data acquisition and evaluation unit.

The basic idea of the invention is to suitably selected, but in itself arbitrarily selected lines of the low-voltage network a Arrangement of at least one non-contact measuring unit and a detection device to be arranged, which measures the current flow in the line and thus the power consumption or the current yield and transmits the registered thereby measured values to an external data acquisition and evaluation. The data exchange between measuring unit and data acquisition and evaluation unit is bidirectional. The measuring unit or the acquisition device are addressed by the data acquisition and evaluation and queried to read the determined measurement data.

each Measuring unit contains a contactless, electrically insulated from the line current transformer. An electrically conductive contact is not necessary. The Measuring unit can in principle arranged anywhere within the low-voltage network be, so that at this point determined Stromertrags- or consumption quantities can be.

Of the Measuring signal converter is expediently as an activated by a shift register A / D converter. This sets the analog current signal of the current transformer digital Measuring signal to.

Of the Measured value memory is activated as one of the shift register Memory and comparator circuit for determining and storing a measured value in the form of a Scanning interval determined maximum value formed. The shift register dissolves the measuring unit a variety of individual measurements for scanning the supplied by the current transformer and digitized by the A / D converter Measuring signal off. The thereby determined maximum value of the digitized Measuring signal forms the measured value determined by the measuring unit.

The Interface to the detection device for bidirectional data exchange is expediently a serial interface, especially an RS232, RS422 or a USB interface. The transmission protocols for such Interfaces are for standardized bidirectional data transmission.

The External data acquisition and evaluation is expediently a computer system equipped with a query and evaluation software, in particular a personal computer. Such computer systems are common equipped with all necessary interfaces for data transmission.

One Method for operating an arrangement for measuring current yield and / or consumption data in a low-voltage grid with the features mentioned itself by the following process steps: It becomes a request signal from the data acquisition and evaluation unit to each one Measurement unit sent. This is followed by a scan through the A / D converter generated digitized sine wave from the current transformer supplied measuring signal and storing a thereby determined Maximum value as measured value. In response, the in the measured value memory stored reading over transfer the interface to the external data acquisition and evaluation unit. It saves and converts the measured value into momentary and / or temporally traceable electricity yield and / or consumption variables, in particular Power, energy yield, energy consumption and / or costs. The calculated Yield or consumption quantities are presented and prepared in a suitable manner.

at several measuring units, the sending of the request signal clocked in succession to each individual measuring unit.

It it does not have to be permanent Measurement of the quantities to be determined, rather, the Measurements in recurring periods, especially at certain times Deadlines, times of day or when needed.

to Preparation and presentation of the calculated electricity yield and / or Consumption sizes will expediently an interactive network, especially in the form of a building plan, with an indication of the circuits, units of measurement, generators and / or consumer generated and the power output and / or consumption sizes broken down to individual rooms and / or individual circuits of the building outline. These Visualization enabled it to query the measured or calculated quantities quickly and easily, being for the user the areas of the respective subnets and their consumers clearly become.

to Preparation and presentation of the calculated electricity yield and / or Consumption sizes can also to the generation of a current yield and / or a consumption curve with a representation of a change a current yield and / or consumption quantity over a series of time intervals, in particular a representation of a performance curve of an energy curve or a cost curve, resorted become. Temporal developments of the measured or calculated Become sizes visible through it.

Expediently, moreover, a representation of a total power yield and / or a total consumption variable, in particular a current strength, an energy amount, a power and / or total costs with a breakdown is carried out and representation of the proportions of the individual measurement units, in particular in the form of a pie chart or bar chart. This makes it possible to present components of individual power sources and, above all, individual consumers in terms of power yields and consumption data, clearly.

The measuring arrangement and the method for operating the measuring arrangement will be explained in more detail below with reference to exemplary embodiments. The same reference numerals are used for identical or identically acting parts or method steps. For clarification serve the attached 1 to 5 , It shows:

1 a schematic arrangement of several measuring units in a subnet of a low voltage network,

2 an exemplary block diagram of a measuring unit and a detection device with the parts contained therein,

3 a more detailed representation of the subcomponents of the individual parts of a measuring unit,

4 an exemplary flowchart of a measured value acquisition, transmission and evaluation,

5 an exemplary visualization for measured value evaluation.

1 shows a subnet of a low voltage network. The subnetwork can be designed very differently depending on the specific design. In the following embodiments, it is assumed that a subnet covering the power supply for several living spaces of an apartment. The following explanations are also applicable to other subnetworks, for example, for commercial premises and workshops, building networks and the like subnets transferable.

In the present case of an apartment is on a riser within a house a branch point 1 arranged. This has the usual circuit facilities, in particular fuses, circuit breakers and the like further means for switching or disconnecting the subnet.

From this branching point branch each a circuit 3 forming conductors, which lead to the individual points of consumption and power connections, ie sockets, with Lästerklemmen armored cable ends and the like connections. In the example shown here, these are a number of external conductors which have a voltage in relation to a grounded neutral point. The outer conductors, as well as the corresponding, not shown here neutral conductor and protective conductor form the subnet of the housing area. The outer conductors have an AC voltage of 230 V in a low-voltage network for the supply of living space. For these, a red, gray or black insulation is specified. The neutral conductor is blue and the protective conductor is striped green-yellow. An outer conductor and the neutral conductor are at each connection point 3a of the subnet. The connection point 3a is usually an indoor or bath socket in the known embodiment as a socket with a protective contact, or a power connection that comes to power electrical stoves or other heaters used.

From an applicable installation plan for the apartment is the assignment of the lines 2 between branch point and junction 3a known. Each of these lines 2 has a measuring unit 4 on. This measuring unit is galvanically isolated on each line 2 arranged and measures the current flowing in the line. For consumption measurements is the line 2 expediently one of the outer conductors. If the measuring unit is attached to a protective conductor, the arrangement thus formed serves as a sensor for a current flowing as a result of line defects. Several of these measuring units are equipped with a detection device 7a coupled, which triggers measuring procedures at the measuring units and receives the measured values determined thereby and to a data processing and evaluation unit 9 forwards.

The external data acquisition and evaluation unit 9 registers the measurement data supplied by the measuring units, converts them into consumption quantities and represents these consumption variables.

2 shows a block diagram of an exemplary measuring unit. The measuring unit contains a current transformer 5 , This has the shape of a hollow cylinder and is annular on the line 2 pushed. In principle, recourse may be had to the embodiments of alternating current sensors known from the prior art for realizing the current transformer.

Current transformers for different measuring ranges, for example ranges from 0 to 20 A, 0 to 50 A or 0 to 200 A, can be used. As a result of the contactless current measurement, the current transformer supplies a voltage value. This is usually in the range of 0 to 5 V. A measuring signal converter 6 puts that from the current transformer 5 generated analog voltage signal into a digital signal and passes the signal to the detection device 7a ,

On in the acquisition device 7a included memory and comparator circuit 7 stores and ver equalizes the digitized voltage signals during a measuring cycle and generates a measured value. An interface 8th , in particular a USB port, or another interface of the serial bidirectional type, provides a connection between the measuring unit and the external data acquisition and evaluation unit 9 ago. As indicated in the figure, other measuring units 4 to the acquisition device 7a be attached and be driven by this. It is also possible that at least one measuring unit and the detection device are housed in a housing.

As in 3 shown contains the Meßsignalumsetzer 6 an A / D converter 11 , The A / D converter digitizes the measurement signal supplied by the current transformer. The measuring signal is present as an alternating voltage. The A / D converter is passed through in the detection device 7a located shift register 10 for an expedient measuring interval, expediently of about 1.5 sine waves of the in the line 2 flowing alternating current, activated. During this time, a large number of current measurements are carried out and the digitized sine wave of the measurement signal is sampled. At a frequency of the alternating current of 50 Hz usual in German low-voltage networks, the time interval defined by 1.5 sine waves is approx. 0.03 s. There is no rectification.

at an expedient embodiment For example, the A / D converter has a bus width of 8 bits. That from the current transformer delivered input signal, so the voltage applied there, is thereby converted into a corresponding digital value. At a Bus width of 8 bits, for example, is the available value stock in the range from 0 to 255. For a current transformer in the measuring range from 0 to 20 A results in a current flow of 20 A in the measured Line and a resulting voltage of 5 V as a measurement signal a digital value of 255.

The memory and comparator circuit 7 contains a comparison element 12 and a memory member 13 , The comparison element 12 executes the sampling of the digitized measurement signal and determines a maximum signal value. When an applied request signal is a in the memory element 13 present value reset to 0. The A / D converter then delivers the first digitized measurement signal. The comparator compares this measurement signal with the value already present in the memory element. If this value is greater, the value given there is overwritten and the larger value is saved as the new value. With the completion of the sampling interval, the maximum measurement signal in digital form is present in the memory element in the sampling interval. This maximum value is sent as a measured value to the data acquisition and evaluation unit.

at This procedure sends the data acquisition and evaluation unit a request signal at fixed intervals, for example at 16 Measuring units every 2 seconds, a request signal. The lands of this Interval is basically arbitrary and can by a corresponding Software be set. But it must be at least as long that successively for each measuring unit in the considered subnet the described measuring steps, i.e. Digitizing and sampling the measurement signal, the determination the maximum signal value and the subsequent transmission of the measured value, is executable.

The Length of the Shift register must be the number of measuring units in the considered Subnet correspond. The shift register activates one after the other every measuring unit for a fixed, for the measurement sufficient sampling interval, expediently in the length of time of 1.5 sine waves of the alternating current flowing in the subnetwork.

Because the shift register activates the measuring units one after the other a separate identification of the measuring units by not necessary. The measured values determined by all measuring units become in a defined order to the data acquisition and evaluation unit Posted. There, the assignment of the incoming measured values takes place the individual measuring units or measuring points on the basis of the shift register and in a mapping table logically the individual measuring points assigned order. For example, in the assignment bar be set that by the shift register as the measured number 1 specific value to the living room, which determined number 2 as a reading Value of the nursery or the value determined as the measured value number 5 the kitchen or the respective subnets is assigned.

In one possible embodiment, the memory element in the detection device is designed as a buffer memory, which stores all measured values determined in a certain period of time together with a time specification and, when called up via the interface 8th outputs. In this case, the memory element is dimensioned sufficiently large in its storage capacity for storing the corresponding data volumes and can be expediently supplemented by an additional memory unit.

The detection device can be externally programmable. It is then possible to specify operating parameters, in particular limit values, in the memory of the measuring unit. For this is a programmable read only memory 13a provided in which predetermined limits and an identification signal for the measuring unit can be stored. The Assignment of an identification signal to the detection device 7a is particularly useful when the subnetwork is large and multiple detection devices are used to control a larger number of measurement units.

Another possible extension of the detection device 7a represents a module 8a for a wireless bi-directional data transmission, which can be attached to the interface of the measuring unit or is also part of the interface. It can be used in particular on a WLAN technology. It is also possible in this context to couple a plurality of detection devices to a common device for wireless data transmission and to carry out communication with the external data acquisition and evaluation unit via this device.

When Data acquisition and evaluation is in particular a common Personal computer used. This has a corresponding interface for bidirectional communication with the acquisition devices and a data acquisition and evaluation software for processing of transmitted to the measuring units Measurement data. These are in particular serial interfaces, preferably USB or RS interfaces for wired data transmissions, or internal or external means connected to the measuring unit for wireless data transmission, especially WLAN modules.

4 shows an exemplary simple flowchart for operating in the 1 to 3 shown arrangement. In one with the reference numeral 15 described step, a request signal from the data acquisition and evaluation is transmitted to one of the measuring units.

The The request signal is generated by the data acquisition unit at a specified time interval. and evaluation sent to the acquisition device and activates the above described measuring process. The sending of the request signal can be manually started or stopped by a user, or automatically over triggered a timer at a fixed start and end time be canceled.

The Timer-controlled transmission of the request signal is particularly then expedient if regularly recurring Procedures for determining power consumption in the subnetwork should. The user manually triggered sending of the request signal allows a determination of an instantaneous consumption which can be carried out at any time. This can be especially useful be when the energy consumption of a currently active electrical Consumer with higher Power consumption, such as a newly installed computer or a new room lighting, certainly or especially energy-intensive power Supplies and line defects are to be determined.

After the start of the measurement process, the data acquisition and evaluation unit sends the request signal to the acquisition device at the specified time interval 7a , There, the shift register is started, which successively activates the individual measuring units in a defined sequence and retrieves the digitized measurement signals from there. Subsequently, as described above, the individual measured values are determined in the detection device and transmitted to the data acquisition and evaluation unit.

As a result, the data acquisition and evaluation unit receives 9 an order of the measured values assigned to the respective consumers and stores these. A factor is used to convert the measured value, which is still available digitally, back into a current value. By adjusting the factor, measurement inaccuracies can be corrected. This adaptation is expediently carried out by means of a calibration with the actual consumption and current values on the existing electricity meter in the subnetwork.

The Thus determined current readings result in each case a current waveform curve, the new values are added at the time of the sent request signals. Small clock cycles with correspondingly small measuring intervals increase the accuracy and the recognition of rapid changes in power consumption, for example, by turning on or off of devices come about. Size Timing cycles with correspondingly larger measurement intervals reduce the computing time and space required and are suitable to track consumption variables over longer periods of time.

In one in the figure by the reference numeral 16 The designated step will be the measured values 17 , optionally together with the measuring unit and / or the detection device 7a uniquely identifying identification signal 18 over the interface 8th transferred to the data processing and evaluation. The measured values 17 from the measurement unit 4 are the immediate raw data about the flow of current in the line. These are converted in the data processing and evaluation unit into actual consumption data as described above. The identification signal 18 ensures that by the request signal actually the right measuring unit or the detection device 7a has been queried. This is particularly advantageous when the subnet is extended and multiple capture devices 7a available.

The queried metrics are in an open array in a database structure stored within the data processing and evaluation unit. For correct classification and for calling the measured values in and out the database is written to the logical mapping table in the data processing and evaluation unit used.

In one with the reference numeral 19 designated further method step, the conversion of the measured values into actual consumption variables. For this purpose, reference is made to the calculation formulas customary in electrical engineering measurement technology. The calculation of the consumption quantities can take place via the measured values supplied by each individual measuring unit and thus to each individual consumer in the network or combined for the measured values of several or all measuring units and thus for several or all consumers.

About appropriate Adjustments to the software in the data acquisition and evaluation unit are without further different times or periods for the consumption measurements chosen Measuring units possible, by suppressing the acquired measured values accordingly, cumulative or otherwise processed. Such is for example the determination of an energy consumption quasi permanently working electrical appliances in the household, such as a refrigerator, for regularly recurring Consumption expedient during the Consumption of certain only temporarily active electrical devices, such as for example a washing machine, always has to be measured when they are in operation.

Over a on the software side given internal allocation table with the logical Assignment between the position of the measuring unit in the signal sequence the transmitted Measurements on the one hand and the user defined location of the electrical consumer with the name of the consumer on the other hand, e.g. "Fifth measurement signal in the time interval - kitchen consumers, "is the one to the individual Measuring units determined energy consumption immediately identified Assigned to consumers. Basically, the user does not have to know more about where the consumer is in the network. However, this assumes that the association between electrical Consumer and measurement unit the logical assignment within the Assignment table not changed becomes.

It It is understood that several current waveforms and consumption values can be summarized for example, a total energy consumption of the analyzed Subnetwork or a section of the multi-user subnetwork to determine. This is the case, for example, if the total contribution all electrical appliances within a living room, nursery and bedroom to To determine the total energy consumption of the apartment. This can be done via appropriate Easily implement software adjustments.

The Consumption variables, such as for example, charge (in ampere hours) and / or energy consumption (in kilowatt hours) as an instantaneous value or as a time average for one or more consumers be determined summarized. If tariff information for the consumption variables is available, can carried out a cost calculation become. Together with an imputed program, the Cost calculations for Forecasts can be used to make predictions about expected Get costs in a billing period.

Of course, also a simple display of the measured values 17 for each individual consumer or several grouped consumers in the network as an instantaneous value of the amperage (for example in amperes) or the instantaneous power consumption (for example in kilowatts).

The calculated consumption quantities are finally in one process step 20 prepared for presentation and appropriately visualized.

5 shows a simple example for the visualization of calculated consumption values. The figure shows elements in a graphical user interface and their contents. In a first window is a floor plan 22 some of the subnetwork supplied rooms, such as an apartment represented. The floor plan contains a schematic representation of the lines laid inside the rooms 23 with the sockets connected through the wires 23a ,

The floor plan is interactive. With a mouse pointer 24 You can click on the individual rooms of the floor plan and retrieve consumption information. For a representation of the consumption quantities at individual outlets 23a a mouse click on the respective plug-in symbol indicated in the floor plan is executed.

Alternatively, as already stated above, electrical consumers of the room itself can be selected and their consumption data queried. The 5 shows a text field 23b with a number of consumers present in the selected room, which are logically linked to individual outlets, ie measurement units, by the evaluation software. The user chooses the legend that interests him the consumer, for example, "TV", the program retrieves the consumption data for the device "TV" corresponding socket and displays.

The consumption data itself can be displayed in different ways. In 5 three examples are shown. Within the graphical representation of the floor plan are pie charts for the respective individual rooms 26 displayed. These indicate a respective proportion of the rooms or of the consumers therein in the total consumption of the apartment shown or of the low-voltage network located inside the apartment.

Another possibility is the display of a time course curve 25 a consumption parameter either via a single consumer, all consumers in one or more rooms or all consumers in the entire apartment, ie over the entire subnet.

Finally, there is the possibility of outputting the consumption quantities in text form. 5 shows a list 27 in a window. In this example of a nursery, the list shows a year-end consumption in the consumption quantities energy (in the unit kWh) and costs (in the unit euro). Furthermore, a weekly consumption average is also listed in the consumption quantities energy (in the unit kWh) and costs (in the unit euro) as well as a peak consumption of a single consumer, in this case a computer connected to a socket A, with a numerical value and with a date ,

The Use of the measuring elements is not limited to consumption measurements. It it is reasonable to assume that use of the described configurations also possible is when a current output of a local voltage source within of the low-voltage network is to be detected and evaluated. This is for example in photovoltaic systems, emergency generators and the like other arrangements possible. In this case are located the measuring elements are dissipated from the voltage sources Lines and register the current flow occurring there.

The mentioned embodiments can also be used in the context of safety equipment of the Use low-voltage network. This concerns in particular the Signaling of a current flow that is too high and exceeds an upper limit in the supervised Conduction, or the detection of a line defect with a finite, as off-limit designated current flow at disconnected from the grid Consumers.

A such application leaves can easily be realized with the described arrangement. For this enough it, within the software of the data acquisition and evaluation unit Limits for to define the registered current flow in each of the lines. If one of the two limits is exceeded, then it will open the data acquisition and evaluation unit issued a warning signal. In particular, it is indicated on which measuring unit the irregular current flow has been registered.

Another possibility for implementing limit value monitoring by means of the presented embodiments is the storage of limit values in the storage and distribution circuit or the read-only memory of the detection device 7a , This can be carried out in particular via the bidirectional interface of the measuring unit. Alternatively, limit values can also be specified on the software side in the data acquisition and evaluation unit.

For signaling an irregular current flow, the detection unit 7a be coupled to a signaling device, such as a buzzer, which outputs a signal when exceeding such limits. It is also possible to transmit this signal output to a safety device, from which an immediate disconnection of the relevant line from the low-voltage network is carried out.

Further embodiments emerge from the dependent claims. In the illustrated exemplary embodiments, in the Framework technical action changes be made, which is also within the scope of the inventive concept fall.

1

branching point

2

management

3

circuit in the subnet

3a

Anschlusstelle

4

measuring unit

5

Power converter

6

Measuring signal converter

7

Storage- and comparator circuit

7a

acquisition device

8th

serial, bidirectional interface

8a

module for wireless data transfer

9

data collection and evaluation unit

10

shift register

11

A / D converter

12

comparator

13

memory element

13a

Only memory

15

request signal send

16

reading and transmit identification signal

17

reading

18

identification signal

19

Convert in consumption sizes

20

To process consumption variables, visualize

22

Plan view

23

shifted cables

23a

sockets

23b

Legend

24

cursor

25

trajectory

26

pie chart

27

listing

Claims (10)

Arrangement for measuring current yield and / or consumption variables in a low-voltage network, characterized by at least one before and / or after one distribution point ( 1 ) on a line ( 2 ) of a circuit ( 3 ) installed measuring unit ( 4 ), comprising a contactless current transformer ( 5 ) for detecting a current flow and an internal measuring signal converter ( 6 ) in conjunction with a detection device ( 7a ) with a measured value memory and an interface ( 8th ) for bidirectional data exchange with an external data acquisition and evaluation unit ( 9 ). Arrangement according to claim 1, characterized in that the measuring signal converter ( 6 ) as a through a shift register ( 10 ) activated A / D converter ( 11 ) is designed to generate a digitized measurement signal. Arrangement according to claim 1 and 2, characterized in that a measured value memory ( 7 ) as one of the shift register ( 10 ) activated memory and comparator circuit ( 11 ) is provided for determining and storing a measured value in the form of a maximum value of the digitized measuring signal determined in a sampling interval. Arrangement according to one of claims 1 to 3, characterized in that the interface ( 8th ) is a serial interface, in particular an RS232, RS422 and / or a USB interface. Arrangement according to one of Claims 1 to 4, characterized that the external data acquisition and evaluation unit with a Query and evaluation software equipped computer system, in particular a personal computer, is. Method for operating an arrangement for measuring current yield and / or consumption variables in a low-voltage network according to one of Claims 1 to 5, characterized by the method steps - sending a request signal ( 15 ) from the data acquisition and evaluation unit ( 9 ) to the at least one measuring unit ( 4 ), - sampling a digitized sine wave generated by the A / D converter of the measurement signal supplied by the current transformer and storing a maximum value determined thereby as a measured value, - transmitting ( 16 ) in the measured value memory ( 7 ) stored measured value ( 17 ) via the interface to the external data acquisition and evaluation unit, - Save and Convert ( 19 ) of the measured value into a momentary and / or time-traceable current yield and / or consumption variable, in particular power, energy yield, energy consumption and / or costs, - processing and presentation ( 20 ) of the calculated electricity yield and / or consumption quantities. Method according to Claim 6, characterized that with several measuring units sending the request signal and determining the measurement value in a unique order for each one Measuring unit takes place. Method according to one of claims 6 or 7, characterized in that for the preparation and presentation of the calculated Stromertrags- and / or consumption variables an interactive network, in particular in the form of a building plan ( 22 ), with an indication of the circuits, measuring units, power generators and / or consumers generated and the power output and / or consumption variables are displayed broken down to individual rooms and / or individual circuits of the building floor plan. Method according to one of claims 6 to 8, characterized in that for the preparation and presentation of the calculated Stromertrags- and / or consumption variables, a current production and / or a consumption curve ( 25 ) with a representation of a change in a current yield and / or consumption variable over a sequence of time intervals, in particular a representation of a Leistungsverlaufs-, a Energieverlaufs- or a cost curve. Method according to one of claims 6 to 9, characterized in that a representation of a total power output and / or a total consumption size, in particular a current, an energy amount, a power and / or total costs with a breakdown and representation of the shares of the individual measuring units, in particular in the form a pie chart ( 26 ), he follows.