Power supply circuit for measuring device and measuring device

Abstract

The invention relates to a power supply circuit (4) for a measuring device (1), comprising a primary energy supply (L1, L2, L3, N) and an additional energy supply (LAUX, NAUX). The two energy supplies are coupled to each other in the supply circuit (4) to form a supply signal. The invention realizes an energy supply with redundancy for continuing to supply power in the event of a failure of the primary energy source, with low cost and less susceptible to failure.

Description

Technical Field

[0001] The invention relates to a circuit for supplying energy to a measuring device and a measuring device having such a supply circuit. Background Art

[0002] Measuring devices for detecting measured values ​​of current loops are usually equipped with an energy supply which is fed by the monitored current loop. Requirements for such power supply solutions are also contained in standards, such as the European Measuring Instruments Directive 2014 / 32 / EU (MID).

[0003] The disadvantage of this solution is that in the event of a measurement voltage failure, the energy supply to the device is no longer guaranteed. In particular, communication with the device is also interrupted. It is not possible to retrieve the measurement data required for diagnosing a measurement voltage failure or correctly determining the power consumption from the outside.

[0004] From document DE 102009048670 A1 it is known to use a storage device as an additional energy source, which is charged by a main energy source (e.g. derived from the measuring voltage). The power supply from the main energy source is monitored. When this energy supply is interrupted, the measuring device switches to the storage device operation by means of a switching device. Summary of the invention

[0005] In this case, a cost-effective and flexible solution is required to ensure the energy supply of the measuring device.

[0006] The technical problem is solved according to the invention by a supply circuit for a measuring device, the supply circuit having a primary energy supply and an additional energy supply, wherein provision is made for the two energy supplies to be interconnected in the supply circuit to form a supply signal. The technical problem is also solved according to the invention by a measuring device having a supply circuit of the aforementioned type.

[0007] According to the present invention, a power supply circuit for a measuring device is proposed, which includes an input terminal for a first energy supply and a second energy supply, which input terminal is also referred to as a "power supply input terminal" below. These energy supplies are referred to as a "primary" energy supply and an "additional" energy supply below. The reason is that the first energy supply ("primary energy supply") is designed to supply energy to the measuring device during normal operation, while the second energy supply ("additional energy supply") is not necessarily designed for the continuous operation of the measuring device. This may also involve the following energy supply, which is designed to maintain the operation of the measuring device for a limited time when the primary energy supply fails. According to the present invention, the two energy supplies are combined into a (single) power supply signal in the power supply circuit, or are connected to provide a (single) power supply signal, and then the electronic components of the measuring device (such as a microcontroller MCU) are fed with power by this power supply signal.

[0008] By combining the two energy supplies in the power supply circuit into one supply signal, the electronic device or MCU to be powered only needs one supply input. This means that the electronic device is only "adapted" to one energy source. There is no need for complex monitoring of different energy sources and, if necessary, no need to switch to an auxiliary voltage source (as described, for example, in document DE 102009048670 A1). Therefore, compared with the prior art, this solution is less complex and ultimately less prone to failure.

[0009] The merging of energy sources into a single power supply signal by means of a power supply circuit should be understood as connecting the power supply inputs to each other by means of a circuit in such a way that only the necessary connections or lines for the electronic device are generated. A bipolar or two-pole interface can be formed by means of a connection portion, for example. Specifically, the inputs of the energy supply can each include at least one (for example three) phase conductor and at least one neutral conductor, and the merging is achieved by connecting a plurality of phase conductors and a plurality of neutral conductors of the energy supply to one phase conductor and one neutral conductor (i.e. two poles), respectively. However, it is also conceivable that the electronic device is supplied with three-phase alternating current. In this case, there are at least three inputs or lines during the connection process (all power supply inputs are connected to three phase conductors and, if necessary, one neutral conductor), and the three-phase alternating current is understood, for example, as a "power supply signal" in the sense of the teaching of the present invention.

[0010] According to one embodiment of the technical solution of the invention, a circuit element for protecting the electronics of the measuring device is provided between the power supply input and the connection for at least one energy supply (preferably two energy supplies). This protection can be provided, for example, by a parallel circuit consisting of a capacitor and an overvoltage arrester (such as a varistor), which are arranged between the phase input to be protected and the neutral conductor input.

[0011] According to one embodiment of the technical solution according to the invention, at least one energy supply provides an AC voltage, and at least one circuit element for voltage rectification (e.g. a rectifier diode) is provided for at least one energy supply between the input and the connection. Any circuit known to the skilled person, such as a half-wave rectifier, a bridge rectifier, a center point rectifier, etc., can be used for voltage rectification. In combination with a protective element (e.g. a parallel circuit consisting of a capacitor and an overvoltage arrester), the at least one circuit element for rectification is provided, for example, between the protective element and the connection of the energy supply. The term "element" here refers to a circuit element or a circuit component.

[0012] According to one embodiment of the supply circuit according to the invention, the supply circuit has a circuit component arranged downstream of the connection for the energy supply and for smoothing and / or filtering the supply signal.

[0013] According to one embodiment of the supply circuit according to the invention, the supply circuit has a circuit component arranged downstream of the connection for the energy supply and for converting a supply signal.

[0014] The invention also relates to a measuring device, for example a so-called PMD (Power Metering & Monitoring Device), which is provided with a power supply circuit according to the invention. The measuring device can be designed to detect measurement data related to a current loop and to extract energy from the current loop as a primary energy supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention is explained below within the scope of an exemplary embodiment. In the accompanying drawings:

[0016] Figure 1 A measuring device for detecting measurement data relating to a current loop is shown, said measuring device being fed by the monitored current loop,

[0017] Figure 2 Show according to Figure 1 a power supply circuit according to the invention for a measuring device, which provides an additional energy source in addition to the feed from the monitored current loop,

[0018] Figure 3 In more circuit details, the Figure 2 The power supply circuit,

[0019] Figure 4 shows a schematic diagram of a measuring device with an energy supply according to the invention, wherein the energy supply is provided by an additional AC voltage source, and

[0020] Figure 5 The schematic diagram shows a measuring device with an energy supply according to the invention, wherein the energy supply is provided by an additional DC voltage source. DETAILED DESCRIPTION

[0021] Figure 1 A measuring device 1 for detecting measurement data associated with a current loop is shown. In addition to current and voltage values, a measuring device known as a PMD (power metering and monitoring device) is also commonly used to determine power consumption data. The determination of such power consumption data can be used, for example, for standardized billing of consumed energy (e.g., according to MID guidelines EN50470-1 / 3 or IECTR 63213 or IEC 61557-12 standard design). However, in general, the invention described below in the context of the embodiments can be applied to any measuring device fed by a current loop.

[0022] The measuring device 1 is connected to the current loop or measurement network to be monitored and receives the measurement data detected by the electronic measuring device or sensor device 3. These measurement data are further processed by the microcontroller or MCU2 (for example, calculating power consumption data). The MCU is also equipped with an interface 5, through which data can be transmitted or read. A power supply or power supply circuit NT is provided to supply energy to the MCU2. The power supply or power supply circuit NT is powered by the monitored circuit and provides a DC voltage of 3.3V to the MCU2. The energy supply from the measurement voltage is referred to as the primary energy supply or primary energy source hereinafter.

[0023] An additional energy supply is provided for the power supply circuit (power supply loop) to ensure power supply. The additional energy supply can be realized, for example, by another current loop, which is usually called "emergency backup device" or "backup power supply", which provides (for example 230V) AC voltage. Alternatively, an uninterruptible power supply can also be used, which is usually called "USV" or "uninterruptible power supply". These uninterruptible power supplies are usually based on batteries. It is also conceivable that the additional energy source is composed of an energy storage device, which is charged by the primary energy source (current loop) (rechargeable battery or separate capacitor).

[0024] The additional power supply input enables the device to be powered by a phase (second current loop) or USV independent of the measurement network. This enables the device to send an alarm to the control center in the event of a power outage and detect a longer period of time. This enables seamless monitoring and digitization of the power supply status.

[0025] Figure 2The interconnection between the primary energy supply and the additional energy supply is shown. Phases L1-L3 of a monitored current circuit and a neutral conductor N are shown here. Both measured values ​​and energy for powering the measuring device are taken from the monitored current circuit in parallel. Figure 2 Shown for Figure 1 1 and MCU 2 are shown in particular. A parallel circuit consisting of a capacitor (capacitor C1-C3) and an overvoltage arrester (e.g., a varistor X1-X3) is provided for each phase L1-L3, which is mainly used to protect the electronic components of the measuring device. Diodes D1-D3 are connected after the parallel circuit consisting of capacitors and overvoltage arresters to rectify the current. A phase connection and a neutral conductor connection L1 are provided. AUX or N AUX An additional energy source or voltage source that provides alternating current to the measuring device. AUX Corresponding to the primary energy supply, a parallel circuit consisting of a capacitor and a discharger C4 or X4 and a diode D4 for rectification is provided. Rectification does not necessarily have to be achieved by means of a diode. Any circuit known to the skilled person, such as a half-wave rectifier, a bridge rectifier (half-bridge or full-bridge), a center point rectifier, etc., can be used for voltage rectification. The phases L1-L3 and L AUX The two neutral conductors N and N AUX The two terminals 101 and 102 (or two poles) are connected to a circuit device 42 for filtering and smoothing, which is also connected in series to a circuit device 43 for converting the voltage into a voltage value suitable for the MCU2.

[0026] Figure 3 Show Figure 2 The energy supply of has other details about the possible implementation of the circuit components 42 and 43, the circuit components have ohmic resistors R2200-R2203, R2206, R2207 and R2209-R2212, capacitors C2200-C2203, C2206, C2207, C2209-C2211, C2213-C2215, C2217 and C2218, coil L2200 with ferromagnetic core, chips N2000 and N2201, optocoupler U2200 and transformer T2200. Specifically, this is a solution implemented by a flyback converter. However, solutions implemented by other types of DC voltage converters are also conceivable.

[0027] Figure 4 Show according to Figure 1Schematic diagram of the energy supply according to the invention in a measuring device. An additional AC voltage energy source is provided. After rectification (functional block 41), the primary energy supply and the additional energy supply are combined (reference symbol 10) and then input into a functional block 42 for filtering or smoothing and a functional block 43 for conversion, thereby providing a DC voltage of 3.3V for MCU2.

[0028] The additional voltage source can also be a DC voltage source. Figure 5 In this case, the rectifier is omitted. However, a circuit element, for example for protecting the entire circuit, can also be arranged in front of the connection.

Claims

1. A power supply circuit (4) for a measuring device (1), the power supply circuit having a primary energy supply (L1, L2, L3, N) and an additional energy supply (L AUX 、N AUX ), It is characterized in that The two energy supplies are connected to each other in the power supply circuit (4) to form a power supply signal.

2. The power supply circuit (4) according to claim 1, It is characterized in that - the input terminals of the energy supply (L1, L2, L3, N, L AUX 、N AUX ) each comprise at least one phase conductor and at least one neutral conductor, and - a plurality of phase conductors (L1, L2, L3, L4) which are respectively supplied with energy AUX ) and multiple neutral conductors (N, N AUX ) to realize the connection part.

3. The power supply circuit (4) according to claim 2, It is characterized in that Circuit elements (C1-C4, X1-X4) for protecting the electronics of the measuring device (1) are provided for at least one energy supply between the input and the connection.

4. The power supply circuit (4) according to claim 2 or 3, It is characterized in that At least one energy supply provides an AC voltage, and at least one circuit element (D1-D4) for voltage rectification is provided for the at least one energy supply between the input and the connection.

5. The power supply circuit (4) according to one of the preceding claims, It is characterized in that The supply circuit is provided with a circuit component (42) arranged downstream of the connection for the energy supply and for smoothing and / or filtering the supply signal.

6. The power supply circuit (4) according to one of the preceding claims, It is characterized in that The power supply circuit is provided with a circuit component (43) arranged downstream of the connection for the energy supply and for converting a power supply signal.

7. A measuring device (1) having a power supply circuit (4) according to one of claims 1 to 6.

8. The measuring device (1) according to claim 7, It is characterized in that - the measuring device (1) is designed to detect measurement data related to the current loop, - Energy is drawn from the current circuit as a primary energy supply.

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