Connecting conductor, arrangement having connecting conductor and use of connecting conductor

Abstract

In order to create a connection conductor (2) for electrically connecting a sensor (6), which provides a measurement signal on the output side, to a smart electronic unit (IED) (13), which is designed for processing the measurement signal, the connection conductor has at least two electrically conductive conductor phases (4a, 4b), which are arranged insulated from one another; a sensor end (9), at which a conductor input (10) for electrically connecting to an output of the sensor is formed; and an evaluation unit end (11) having a conductor output (12) for electrical connection to the input of the evaluation unit, the two conductor phases extending from the conductor input to the conductor output and being designed to transmit a measurement signal between the output of the sensor and the input of the evaluation unit, measurement errors due to high-frequency interference are avoided in the connecting conductor, and the connecting conductor is adapted to the frequency range in which interference occurs.

Description

Technical Field

[0001] The present invention relates to a connecting conductor for electrically connecting a sensor providing a measurement signal on the output side to an intelligent electronic unit (IED), which is designed to process the measurement signal. The connecting conductor has: at least two conductive conductors arranged insulated from each other; a sensor end, at which a conductor input for electrically connecting to the output of the sensor is formed; and an evaluation unit end, which has a conductor output for electrically connecting to the input of the evaluation unit, wherein the two conductors extend from the conductor input to the conductor output and are designed to transmit the measurement signal between the output of the sensor and the input of the evaluation unit.

[0002] Furthermore, the present invention relates to a device for use in the field of power supply, which has a sensor for acquiring electrical parameters of the conductor joints of a power supply network, an intelligent electronic unit (IED), and a connecting conductor extending between the sensor and the IED.

[0003] Furthermore, the present invention relates to an application of a connecting conductor for transmitting a measurement signal between a current sensor and an IED. Background Art

[0004] Such connecting conductors and such devices are known to those skilled in the art from practice. Therefore, currently, connecting cables are used to connect a sensor or a sensor head providing an analog current measurement value on the output side to an intelligent electronic unit, such as a merging unit or a protection device. Here, the sensor head has an annular measurement part that surrounds the phase conductors of the multi-phase conductors of the power supply network. Then, the current flowing through the phase conductors induces a voltage corresponding to the current flowing in the phase conductors in the annular measurement part. Therefore, after calibrating the sensor, the current in the phase conductors can be measured.

[0005] However, it has been proven that events occurring around the connecting conductor, such as the switching of a circuit breaker, may generate electromagnetic interference, which may have an adverse effect on the measurement accuracy of the sensor head. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a connecting conductor of the type mentioned at the beginning, which is insensitive to external transient electromagnetic interference radiation.

[0007] According to the present invention, based on the connecting conductor mentioned above, the above technical problem is solved by adapting the connecting conductor to the frequency range in which interference occurs.

[0008] It has been recognized within the scope of the present invention that such transient interference events generate alternating fields (electromagnetic radiation) that may be in the high-frequency range, for example, in the megahertz range. In the case where the connecting conductors are not properly adapted to these frequencies, these transient interference fields distort the measurement results. Therefore, according to the present invention, it is proposed to adapt the connecting cable to these interference frequencies. By making the adaptation, the connecting conductors are insensitive to the high-frequency interference fields in the sense that they can reliably acquire the measured values collected during high-frequency interference.

[0009] Although tuned connecting cables are known to those skilled in the art in principle from the high-frequency field, the present invention proposes a connecting conductor that is adapted to interference frequencies in a higher frequency range for the transmission of measured values in the millisecond range. Currently, only unadapted connecting conductors are used for this purpose. This is because the power supply network conducts alternating voltage and has an alternating voltage with a fundamental oscillation of 50 Hz or 60 Hz.

[0010] The adaptation is preferably carried out by means of terminating resistors. Thus, each phase conductor (4a, 4b) can have a terminating resistor, and each terminating resistor is arranged at the sensor end. This adaptation is cost-effective.

[0011] Advantageously, a capacitance is formed between the conductor input and the terminating resistor of the phase conductor. Since the sensor head also forms a capacitance, or in other words a capacitor, with respect to the corresponding phase of the conductor of the power supply network surrounded by its annular measuring part, according to this advantageous expansion of the present invention, a series circuit of two capacitors is provided by an additional capacitor, or in other words by an additional capacitance. This series circuit can also be referred to as a capacitive voltage divider. Here, one of the conductor phases of the connecting conductor is connected to one pole of the first and second capacitors connected downstream of the sensor. According to the present invention, when using the connecting conductor, the other conductor phase is preferably grounded. In other words, the other conductor phase can be grounded, or in other words can be at ground potential.

[0012] The capacitance is advantageously arranged between the conductor input and the terminating resistor of the phase conductor. It has been proven that this electrical device is most suitable for making the connecting conductor insensitive to high-frequency interference fields.

[0013] According to another variant of the present invention, the phase conductors extend in a plastic housing, so that the connecting conductors are designed as cable conductors. The cable conductors can be easily and quickly laid or connected on site.

[0014] Furthermore, the present invention relates to a device for use in the field of electrical power supply, which device has a sensor for acquiring electrical parameters at the phase conductors of an electrical power supply network, an intelligent electronic unit (IED), and a connecting conductor designed as described above, which connecting conductor extends between the sensor and the IED. The above description correspondingly applies to the device according to the present invention.

[0015] Finally, the present invention also relates to an application of the connecting conductor according to any one of the foregoing claims for transmitting measurement signals between a current sensor and an IED. Tuned or terminator-equipped connecting conductors are in principle known from the field of high-frequency technology. However, so far, no application thereof for transmitting analog measurement values between a sensor and an IED has been proposed.

[0016] According to an expansion scheme in this regard, the IED is a protection device, a merging unit, or a PMU (Phasor Measurement Unit). Description of the Drawings

[0017] The present invention will be described in detail below with reference to embodiments, wherein the same reference numerals indicate components having the same functions, and in the drawings:

[0018] Figure 1 An embodiment of a device with a connecting cable according to the prior art is shown,

[0019] Figure 2 An embodiment of the connecting cable according to the present invention is shown, and

[0020] Figure 3 An embodiment of the device according to the present invention is shown. Detailed Description of the Embodiment

[0021] Figure 1 An embodiment of the device 1 according to the prior art is shown. The device 1 has a connecting conductor 2, which is designed as a connecting cable 2. The connecting cable 2 includes a cable plug 3 and two conductor phases 4a and 4b, and the two conductor phases 4a and 4b are arranged in a plastic housing 5 in an electrically insulated manner from each other. The plastic housing 5 completely surrounds the conductor phases 4a and 4b. The reference numeral 17 indicates that the conductor phase 4a is at ground potential. This grounding can be carried out through the IED.

[0022] The cable plug 3 is connected to the sensor 6, which has an annular ring conductor that is arranged in electrical insulation, for example, in a plastic housing filled with glass fibers. The sensor 6 is designed to collect the current flowing through the phase conductor of the power supply network. Here, the ring conductor of the sensor 6 surrounds one of the phase conductors of a polyphase, for example, three-phase, power supply network. Since the phase conductor conducts an alternating voltage, a small alternating current flows through the capacitance between the phase conductor and the metal ring conductor of the sensor. This current is proportional to the voltage applied in the corresponding phase of the energy supply network, so that the voltage can be measured after calibrating the sensor 6.

[0023] In Figure 1 the ring conductor of the sensor head 6 is schematically shown by a capacitor 7. Another capacitor 8 can be seen in the cable plug 3, which is arranged between the conductor phases 4a and 4b of the connecting cable 2. The capacitors 7 and 8 are connected in series and form a capacitive voltage divider. Therefore, by appropriately selecting the sizes of the capacitors 7 and 8, the desired voltage range for measuring the voltage between the conductor phases 4a and 4b can be determined. In the illustrated embodiment, the capacitor 8 is soldered between the conductor phases 4a and 4b. The conductor phase 4b is connected to the corresponding pole of the two capacitors connected in series. As shown by the reference numeral 17, the pole of the capacitor 4a connected to the conductor phase 4a is at ground potential.

[0024] At the sensor end 9 of the connecting conductor 2, the connecting conductor 2 forms a conductor input end 10, which is configured for electrical connection to the output end of the sensor head 6. The conductor input end 10 is formed, for example, by a plurality of rigid connection pins protruding perpendicular to the plane of the non-conductive housing, which can be inserted into the corresponding holes of the sensor head 6.

[0025] At the end of the connecting cable 2 remote from the sensor 6 (hereinafter referred to as the evaluation unit end 11), the connecting cable 2 forms a conductor output end 12, which is used for connection to the protection device 13. The protection device 13 is one of many possibilities of the design of an intelligent electronic unit called "intelligent electronic device (IED)" in English.

[0026] It can be seen that the conductor phases 4a and 4b of the connecting cable 2 extend into the protection device 13. The connecting conductors extending in the protection device 13 are provided with reference numerals 14a and 14b. A resistor 16 is connected between the connecting conductors 14a and 14b, and the resistor 16 here has a magnitude of 2 MΩ (megaohm). A capacitance in the form of a capacitor 15 (30 pF to approximately 50 pF) is connected in parallel with the resistor 16. The capacitor 15 and the parallel-connected resistor 16 are pre-given by the so-called LowPowerInstrumentTransformer Normung (Low Power Instrument Transformer Specification). Technically speaking, the capacitance is physically formed by the actual input circuit of the IED. The value is partly formed by the circuit board capacitance and the semiconductor input impedance. In other words, this structure is automatically generated, and without this additional capacitance generated, the IED cannot be realized. By extending the conductor phases, at the end of the evaluation unit, the resistor becomes effective between the conductor phases 4a and 4b.

[0027] As already described above, the connecting conductor 2 according to the prior art and the device 1 formed thereby according to the prior art have the disadvantage that external high-frequency interference may affect the measurement result. An example of such interference is the switching of a circuit breaker. It has been recognized within the scope of the present invention that the electromagnetic field formed here may have a frequency in the megahertz range. When the cable conductor is tuned to such high-frequency interference, the measurement error caused by such high-frequency interference can be avoided. Figure 2 This connecting cable 2 according to the present invention is shown.

[0028] Figure 2 An embodiment of the connecting conductor 2 according to the present invention is shown, which is designed as the connecting cable 2 as in Figure 1 ... The connecting cable 2 according to the present invention shown has the same components as the connecting cable 2 according to the prior art shown in Figure 1 ... Therefore, if the description regarding Figure 1 relates to the connecting cable 2, it correspondingly applies to Figure 2 ...

[0029] However, different from the connecting cable 2 according to Figure 1 ..., the connecting cable 2 according to Figure 2 ... has two terminal resistors 18a and 18b, which are respectively arranged in one of the conductor phases 4a and 4b. In the example shown, the terminal resistors 18a and 18b form a resistor of 68 Ω, and the validity is also given with a value 10% larger or 10% smaller. Thus, the connecting cable 2 shown is adapted and optimized to dissipate interference in the range of approximately 3 MHz to far above 30 MHz and convert it into heat. Due to the terminal resistors 18a and 18b, according to Figure 2The connecting cable 2 is no longer prone to malfunctions due to high-frequency interference, so the measurement results can no longer be distorted.

[0030] Figure 3 An embodiment of the device 1 according to the invention is also shown schematically. According to Figure 3 the device 1 basically corresponds to the illustration of the prior art according to Figure 1 however, in which the terminating resistors 18a and 18b are inserted into the conductor phases 4a and 4b again. In Figure 3 the embodiment shown, corresponding to 18a and 18b, the terminating resistor 1 has a resistance of 68 Ω. The connecting cable is thus tuned to dissipate interference in the range of approximately 1 MHz to approximately 50 MHz in a broadband manner. Due to this tuning, the measurement results can no longer be distorted by high-frequency interference. In other respects, the descriptions regarding Figure 1 and Figure 2 apply correspondingly here.

Claims

1. A connecting conductor (2) for electrically connecting a sensor (6) providing a measurement signal on the output side to an intelligent electronic unit (IED) (13), the intelligent electronic unit being designed to process the measurement signal, the connecting conductor comprising: at least two electrically conductive conductor phases (4a, 4b) arranged insulated from one another, a sensor end (9) at which a conductor input (10) is formed for electrical connection to an output of the sensor (6), and an evaluation unit end (11) having a conductor output (12) for electrical connection to an input of an evaluation unit (13), -in, Two conductor phases (4a, 4b) extend from the conductor input (10) to the conductor output (12) and are designed to transmit the measurement signal between the output of the sensor and the input of the evaluation unit, It is characterized in that The connecting conductor (1) is adapted to the frequency range in which interference occurs.

2. The connecting conductor (2) according to claim 1, It is characterized in that Each phase conductor (4a, 4b) has a terminating resistor (18a, 18b), wherein each terminating resistor (18a, 18b) is arranged at the sensor end (9).

3. The connecting conductor (2) according to claim 2, It is characterized in that A capacitance (8) is formed between the conductor phases (4a, 4b) at the sensor end (9).

4. The connecting conductor (2) according to claim 3, It is characterized in that The capacitor (8) is arranged between the conductor input (10) and a terminating resistor (18a, 18b) of a conductor phase (4a, 4b).

5. The connecting conductor (2) according to any one of the preceding claims, It is characterized in that The phase conductor (2) extends in a plastic housing (5), so that the connecting conductor is designed as a connecting cable (2).

6. The connecting conductor (2) according to any one of the preceding claims, It is characterized in that At the evaluation unit end, a resistor is effective between the conductor phases.

7. A device (1) for use in the field of electrical energy supply, comprising: A sensor for detecting an electrical variable of a conductor of an electrical energy supply network, an intelligent electronic unit (IED) and a connecting conductor according to any of the preceding claims, the connecting conductor extending between the sensor and the IED.

8. Use of a connecting conductor (2) according to any one of claims 1 to 6 for error-free transmission of measurement signals between a sensor (6) and an IED (13).

9. Use of a connecting conductor (2) according to any one of claims 1 to 6 for error-free transmission of measurement signals between a sensor (6) and a protective device (13).

Images