DE102008013943B4 - Hot water storage and test device for testing an anode in a hot water tank - Google Patents

Abstract

Hot water storage, with
an enamelled container (3),
a container isolated to the anode (2), and
a measured value detection and evaluation unit for detecting an anode current and for comparing the detected anode current values with at least one threshold value, wherein based on the comparison, a change of the detected anode current over time is detected.

Description

The present invention relates to a hot water storage and a test device for testing an anode in a hot water storage.

In hot water stores with a steel enamelled store, an anode is typically used as corrosion protection. Thus, for example, defects in enamelling can be protected.

DE 10 2004 004 064 A1 shows a device for monitoring the consumption of an anode in a hot water storage tank. The anode is connected via an electrical line to a circuit device and the circuit device is connected via a further line to the wall of the hot water storage tank. A voltage is applied between the two electrical lines. The circuit device detects the current of the voltage source and compares this value with a limit value. If the limit value is undershot, a signal indicating the wear of the anode is output. Thus, a measurement of the anode current and the protection current, which is used as an indicator of the state of the anode.

It is therefore an object of the present invention to provide a hot water storage, which has an improved ability to test the anode used.

This object is achieved by a hot water storage according to claim 1.

The invention thus relates to the idea to provide a hot water tank with an enamelled steel container, an insulated anode and a Meßwerterfassungs- and evaluation. In this case, the anode current is measured, wherein the anode is configured isolated from the memory. During the measuring process, the connection between the anode and the container is interrupted. On the basis of the anode current conclusions can be drawn with regard to the quality of the enamel and water, in particular the conductivity of the water, as well as the size of the anode used. When the memory is first started up, the anode current is measured and stored as the initial value or value. The measured value acquisition and evaluation unit checks the consumption value of the anode. For this purpose, the measured value acquisition and evaluation unit can determine the current anode protection current and compare this with a value which is stored in the measured value acquisition and evaluation unit. Alternatively, the determined value may be compared to a calculated upper and lower threshold. If the determined or measured value exceeds the absolute or relative threshold, then conclusions can be drawn on the wear of the anode and on certain operating states of the memory.

Further embodiments of the invention are the subject of the dependent claims.

• 1 zeigt eine schematische Darstellung eines Warmwasser-Speichers gemäß einem ersten Ausführungsbeispiel,
• 2 zeigt eine Teilschnittansicht eines Speicherbehälters mit einer Anode gemäß einem zweiten Ausführungsbeispiel, und
• 3 zeigt einen Graphen eines Anodenstromverlaufs über eine Betriebszeit eines Warmwasser-Speichers gemäß dem dritten Ausführungsbeispiel.

Embodiments and advantages of the invention are explained below with reference to the drawing.

• 1 shows a schematic representation of a hot water storage according to a first embodiment,
• 2 shows a partial sectional view of a storage container with an anode according to a second embodiment, and
• 3 FIG. 12 is a graph showing an anode current waveform over an operation time of a hot water storage according to the third embodiment. FIG.

1 shows a schematic representation of a hot water storage according to the first embodiment. The hot water tank has a container 3 with an anode 2 on, which by means of an insulating body 1 opposite the container 3 is isolated. The hot water tank also has a switch 5 as well as an ammeter 4 on, which with the anode 2 , the switch 5 and with the container 3 is coupled. Alternatively, in the pipe 6 a resistor or a diode may be coupled. The container 3 in turn is grounded PE. By means of the switch 5 can the anode with the container 3 be connected or from the container 3 be decoupled. In operation, the anode becomes 2 with the container 3 connected. However, if a measurement of the anode current by means of the current measuring device 4 should be performed, then the switch 5 operated and the connection between the anode 2 and the container 3 will be interrupted. Now, the anode current can be determined according to the first embodiment.

2 shows a partial sectional view of a container of a hot water storage according to a second embodiment. In 2 is in particular the cutout of the container 3 shown where the anode is installed. As already described in the first embodiment, the anode becomes 2 by means of an insulating body 1 from the container 3 isolated.

3 shows a graph of the anode current waveform over the operating time according to a third embodiment. In 3 is an absolute threshold AOS, an absolute lower threshold OFF and a relative threshold RS and the course of the anode current shown. The anode current depends on the quality of the enamel, the water quality and the size of the anode used.

A Meßwerterfassungs- and evaluation, which the switch 5 , the electricity meter 4 and the resistor may further include a memory for storing anode current values. For example, the anode current can be measured during an initial startup of the memory and stored in the memory. Furthermore, the enamel quality and the water quality can also be saved. The measured value detection and evaluation unit detects the anode protection current and compares this value with values stored in the memory.

Alternatively or additionally, the determined anode protection current values can be compared with a calculated or calculated upper absolute threshold value AOS and / or a lower absolute threshold value AUS. If the determined anode protection current falls below the upper or lower threshold, then it can be concluded from these underflows or exceedances on certain operating states of the memory.

For example, a drying path of the memory can be detected. During the drying cycle of the storage tank, there may be no water in the storage tank. Thus, the radiator of the memory glows. Since there is no water in the reservoir, no anode current can flow. The absence of the anode current is detected by the Meßwerterfassungs- and evaluation and a corresponding warning signal can be output.

Furthermore, a passivated anode can be detected. As a result of self-corrosion, an oxide layer can form on the anode over time, so that the anode function is extinguished. The Meßwerterfassungs- and evaluation electronics can detect this condition, in particular, the course of the anode current is measured over time and a corresponding decrease of the anode current can be detected. If such a state is reached, then the measured value and evaluation unit can output a corresponding warning signal.

Furthermore, a short circuit can be detected. Such a short circuit may occur when the anode is no longer isolated from the container. The measured value detection and evaluation unit can also detect this condition and possibly output an alarm signal.

When an upper threshold value is exceeded, for example because the anode current is too high, this can also be determined by the measured value detection and evaluation unit and a corresponding warning signal can be output. Too high an anodic current can occur, for example, when the conductivity of the water is too high or too many defects are present in the enamel of the container.

If one of the states described above occurs, then the measured value acquisition and evaluation unit can recognize, classify the error (for example by comparison with stored threshold values) and can output a fault message.

If the anode current falls below a relative or absolute lower threshold, then this can be an indication that the anode has to be changed. In this case, however, in particular the time profile of the anode current is taken into account to determine whether the anode is consumed. As a threshold for determining whether an anode change is needed, an absolute threshold or relative threshold relative to the relative drop in anode current to the output current signal may be determined.

The measured value acquisition and evaluation unit can automatically check the anode current at regular intervals. If the absolute or relative threshold value is undershot, this undershoot can be displayed.

After a change of anode, a recalibration can be performed, again measuring the anode current.

The hot water storage described above can have both a container under pressure and a non-pressurized storage.

Claims (4)

Hot water storage, with an enamelled container (3), a container isolated to the anode (2), and a measured value detection and evaluation unit for detecting an anode current and for comparing the detected anode current values with at least one threshold value, wherein based on the comparison, a change of the detected anode current over time is detected. Hot water storage after Claim 1 , whereby different qualities of the enamel and the water conductivity are taken into account by the measured value detection and evaluation unit and stored accordingly. Hot water storage after Claim 1 or 2 , wherein the Meßwerterfassungs- and evaluation is designed to, when commissioning the Hot water storage to capture and store an initial value of the anode current. Hot water storage after one of Claims 1 to 3 wherein the Meßwerterfassungs- and evaluation is designed to compare the detected anode current with an absolute upper threshold (AOS), an absolute lower threshold (OFF) and / or a relative threshold (RS).

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