CH638043A5 - Arrangement for the central measurement of the thermal energy drawn by a plurality of heat consumers - Google Patents

Description

638 043

PATENT CLAIMS

1. Arrangement for the central recording of the heat energy obtained from several heat consumers, with several measuring devices, each assigned to one of the consumers,

which are connected to a central device via a common collecting line, each measuring device containing a flow meter and a computing element being arranged either in each measuring device or in the central device, each of which generates an energy quantity pulse after the consumption of a fixed amount of energy, which in a io rather assigned heat quantity counter is added up, furthermore the energy fixed quantity impulses or flow fixed quantity impulses generated by the flow meter in the form of a codeword containing the address of the consumer are transmitted from the measuring device via the collecting line to the central device, characterized in that in the Measuring device (1 to 3; 27), a timer (15) is arranged, which periodically triggers the transmission of a code word of a second type (B) to the central device (5), and that an alarm element (16) is present in the central device (5) that responds when given within a en no code word arrives from an address.

2. 'Arrangement according to claim 1, characterized in that the timing element (15) is reset by each energy fixed quantity pulse or flow fixed quantity pulse. 25th

3. Arrangement according to claim 1 or 2, characterized in that the alarm element (16) responds when a flow temperature sensor (7), a return temperature sensor (8) and / or other condition sensors (19) of the measuring device

(1 to 3; 27) Detect irregular states or changes. 30th

4. Arrangement according to claim 3, characterized by a detector (17) for monitoring the rate of change of the measured values from the temperature sensors (7; 8) (Tv; Tr).

5. Arrangement according to claim 3, characterized by 35 a detector (18) for monitoring the difference between the measured values from the temperature sensors (7; 8) (Tv; Tr).

6. Arrangement according to one of claims 3 to 5, characterized by a in the flow meter (6) arranged pressure switch (19). 40

7. Arrangement according to one of claims 3 to 6, characterized in that the measuring device (1 to 3; 27) is set up to generate a code word of a third type (C) and transmits this via the bus (4) to the central device (5) , if the flow temperature sensor (7), the return temperature sensor (8) or other condition sensors (19) detect the irregular conditions or changes.

8. Arrangement according to claim 3, characterized in that the alarm element (16) responds when the deviation of the flow temperature sensors (7) of the measuring devices 50 (1 to 3; 27) detected flow temperatures (Tv) exceeds a predetermined value.

9. Arrangement according to one of the preceding claims, characterized in that the collecting line (4) is a two-wire line. 55

10. The arrangement according to claim 9, characterized in that the measuring devices (1 to 3; 27) are fed from the two-wire line (4).

An arrangement of the type specified in the preamble of claim 1 is known (DE-OS 27 22 485), in which the decentralized measuring devices are polled cyclically by the central device 65 and in this case forward the measured temperature difference via a collecting line to the central device if there is a water quantity contact of the Flow meter of the

Measuring device had addressed since the last query. The bus consists of a clock line, an address line, a data line and a voltage supply line. Addressing takes place in that each measuring device has an address flip-flop, all flip-flops are connected to a shift register and the central device shifts a signal through this shift register. If one of these flip-flops is no longer functional as a result of a fault or interruption in the voltage supply, the shift register is interrupted and the measurement value transmission of measuring devices which are still functional per se is thereby deactivated.

The invention specified in claim 1 has for its object to provide an arrangement of the type mentioned, in which a failure of the power supply or other faults in one of the measuring devices are indicated by the central device and no failure of the measured value transmission from the other measuring devices results, to have.

Some exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Show it: •

Fig. 1 is a schematic diagram of an arrangement for central detection of the heat energy obtained from several heat consumers and

2 shows a basic circuit diagram of a measuring device.

1, 1, 2 and 3 mean decentralized measuring devices which are connected to a central device 5 via a common collecting line 4. Each of the identically constructed measuring devices 1 to 3 is assigned to a heat consumer (not shown) and has a flow meter 6, a flow temperature sensor 7 and a return temperature sensor 8. The flow meter 6 measures the volume flow V; the flow temperature sensor 7 the outlet temperature Tv and the return temperature sensor 8 the return temperature Tr of a heat transfer medium that flows in a supply line to the relevant heat consumer and in a return line to the heat source.

A computing element 9 determines e.g. according to the formula Q = k f V (Tv - Tr) dt, the thermal energy Q obtained by the consumer and generates an energy fixed quantity pulse at its output after the consumption of a predetermined fixed quantity of energy. A transmitting member 10 converts each fixed quantity of energy pulse into a code word of the type A containing the address of the energy consumer and sends this code word, if the collecting line 4 is not already occupied by one of the other measuring devices 2 or 3, in the form of a pulse telegram via the collecting line 4 to one Evaluation element

11 of the central device 5. If the collecting line 4 is already occupied, the transmission of the code word is waited until it is free again. Such transmission methods have the advantage that a call for measurement value transmission by the central device 5 and thus a receiver in the individual measuring devices 1 to 3 are not necessary. A two-wire line can be used as the collecting line 4, which also serves for the voltage supply of the measuring devices 1 to 3.

The central device 5 has a plurality of heat meters

12 to 14, each of which is assigned to one of the measuring devices 1 to 3. If a code word of type A arrives in the central device 5, the evaluation element 11 emits a fixed-energy quantity pulse to the relevant heat quantity counter 12, 13 or 14 in accordance with the address of the code word. In these, the energy quantity impulses are added up, and the thermal energy obtained from the various consumers is displayed.

In each of the measuring devices 1 to 3, a timing element 15 is arranged, which is output by each of the computing element 9

3rd

638 043

Fixed energy quantity pulse is reset and periodically triggers the transmission of a code word of the type B containing the address of the consumer to the central device 5 after a predetermined period of time Ta. If, within a period of time Tb, which is to be selected somewhat longer than Ta in accordance with the possible delays, neither the code word of type A nor the code word of type B arrives in the central device 5 from an address, the evaluation element 11 emits a control signal to an alarm element 16 , which triggers an alarm, which indicates a malfunction in the relevant measuring device or an attempt to defraud, for example by interrupting the power supply. The central device 5 advantageously has a display element in which the address of the functional measuring device is displayed.

To monitor the time intervals of the code words received, the evaluation element 11 can have a timer for each address, which is restarted by each incoming code word of type A or B of the relevant address and triggers an alarm after the time period Tb. However, a microcomputer, which writes the time of the arrival of the last code word in a memory for each address and triggers an alarm as soon as a time recorded in the memory has exceeded the time interval Tb, advantageously serves as the evaluation element 11.

The timing element 15 of the measuring devices 1 to 3 can also be operated in such a way that it triggers the transmission of a code word of the type B to the central device 5 periodically regardless of the fixed energy quantity pulses. In this case, the evaluation element 11 has to trigger an alarm if no code word of the type B arrives in the central unit 5 from one of the various addresses within the time period Tb. However, the previously mentioned possibility of sending out a code word of type B only after no fixed energy quantity pulse has occurred during the time period Ta has the advantage that the bus 4 is occupied less frequently.

It is advantageously ensured that the alarm element 16 also responds when the flow temperature sensor 7, the return temperature sensor 8 and / or other state sensors detect irregular states or changes. For this purpose, a detector 17 for monitoring the rate of change of the measured values Tv and Tr determined by the temperature sensors 7, 8, a detector 18 for monitoring the difference between the measured values Tv and Tr, and a pressure switch 19 are provided in the measuring devices 1 to 3, which are controlled by an OR -Gate 20 control the transmission element 10 and trigger the transmission of a code word of type C to the central device 5. If a code word of the type C arrives in the evaluation element 11, the alarm element 11 is activated immediately.

In the example shown, the detector 17 consists of differentiators 21, 22 for forming the time derivatives dT

v dT

and dt dt and from threshold switches 23, 24 which respond when the time derivative of the measured value Tv or Tr exceeds a predetermined threshold value. Does the measured value Tv or Tr change as a result of a malfunction or attempted fraud e.g.

by interrupting the sensor lead or removing the temperature sensor from the measuring point faster than is possible in normal operation due to the time constant, an alarm is given.

The detector 18 is formed by a differential element 25 and a threshold switch 26. It responds when the temperature difference AT = Tv - Tr exceeds a predetermined negative value, which is matched to the measuring accuracy of the temperature sensors 7, 8, which indicates a malfunction or attempted fraud.

The pressure-5 monitor 19, which is advantageously arranged in the flow meter 6, monitors the static pressure in the heat pipe network and triggers an alarm if the static pressure falls below a predetermined minimum value. This also gives an alarm when a consumer fraudulently removes the flow meter 6 from the heat pipe network.

If the transmission of the code words of type B is independent of the delivery of fixed energy quantity pulses, the alarm can also be passed on from the OR gate 20 to the alarm element 16 by the OR gate 20 blocking the outside of the code word of the type B, so that after the time period Tb the alarm element 16 responds.

The generation of the fixed energy quantity impulses from the measured values of the volume flow V, the flow temperature, Tv and the return temperature Tr can also take place in the evaluation element 11 of the central unit 5 instead of in each individual measuring device 1 to 3. FIG. 2 shows a measuring device 27 intended for this case, the flow meter 6 of which generates a fixed flow rate pulse after the flow of a predetermined flow rate of the heat carrier. A transmission element 28 converts each fixed flow quantity pulse into a code word of the type A and sends this via the bus 4 to the central device 5 (FIG. 1). The timer 15 is reset by each flow rate fixed quantity pulse and triggers the transmission of a code word of type B after the time period Ta peri-30. The analog measured values Tv and Tr ascertained by the temperature sensors 7, 8 are converted into digital signals in an analog-digital converter 29 and are coupled into the collecting line 4 via the transmission element 28.

35 The thermal energy Q obtained from the various consumers is stored in the evaluation element 11 (Fig. 1) e.g. calculated according to the formula Q = kf V (Tv - Tr) dt and displayed in the associated heat quantity counter 12, 13 or 14. It is also advantageously checked in the evaluation element 11 whether the measured values detected by the flow temperature sensors 7 of the various measuring devices are similar to the flow temperature Tv. If the deviation of the flow temperatures Tv exceeds a predetermined value, which in turn suggests a malfunction or an attempt at fraud, the alarm is triggered. The examination of the rate of change of the measured values detected by the temperature sensors 7, 8 and the verification of the sign of the temperature difference AT = Tv - Tr explained with reference to FIG. 1 can also be carried out in the evaluation element 11.

The temperature sensors 7, 8 in the measuring devices 27 can be omitted if instead the flow temperature is measured with a flow temperature sensor common to all consumers and the determination of the thermal energy Qv to be paid by the consumer on the basis of a fictitious return temperature T "e.g. according to the formula Qv = kj V (Tv - Trv) dt. The substitution of the actual return temperature Tr by the fictitious return temperature Trv affects the measurement result in such a way that consumers who operate their heat consumers with a low temperature difference of 60 AT have to pay a comparatively higher energy price than consumers who due to a high temperature difference AT one contribute to the optimal utilization of the capacity of the heat pipe network and a good efficiency of the heating plant.

65 The digital operations to be carried out in measuring devices 1 to 3 and 27 can advantageously be carried out by means of a microcomputer.

1 sheet of drawings