CN215219064U - Measuring device - Google Patents
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- CN215219064U CN215219064U CN202120365468.6U CN202120365468U CN215219064U CN 215219064 U CN215219064 U CN 215219064U CN 202120365468 U CN202120365468 U CN 202120365468U CN 215219064 U CN215219064 U CN 215219064U
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Abstract
The utility model provides a measuring device, it includes: a current sensor for sensing a current of the measured loop and outputting a differential current signal corresponding to the current of the loop; a first measurement circuit that outputs a first digital current signal corresponding to a current of the loop when the differential current signal is not higher than a first predetermined value; a second measuring circuit outputting a second digital current signal corresponding to the current of the loop when the differential current signal is higher than the first predetermined value; and a processing and communication circuit which determines a first characteristic value corresponding to the current of the loop from the first digital current signal or the second digital current signal when the circuit breaker is open and transmits the first characteristic value to an external device, wherein the first measurement circuit includes a voltage clamp circuit which clamps the differential current signal when the differential current signal is higher than a second predetermined value, the second predetermined value being greater than the first predetermined value.
Description
Technical Field
The present invention relates to a measuring device, and more particularly, to a measuring device as an accessory for a circuit breaker.
Background
The circuit breaker is an important protection component in the field of power distribution, and once overload current or short-circuit current appears in a circuit of the circuit breaker, the circuit breaker can quickly cut off a load to protect a cable. Currently, the auxiliary contacts OF the circuit breaker mainly include an auxiliary contact (OF), a trip indicating contact (SD), and a fault indicating contact (SDE), but they can only indicate a contact opening/closing state, whether the circuit is broken due to a leakage point test button, whether the circuit is broken due to a fault, but cannot provide a current when the circuit breaker is broken, and further cannot determine the cause OF the circuit breaker such as overload, short circuit, and the like based on the current.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a can measure the device of the electric current when circuit breaker opens circuit to supply the basis of maintainer as the line troubleshooting.
The utility model provides a measuring device, its characterized in that includes: the current sensor is used for being connected with a wire outlet end of the circuit breaker, sensing the current of a detected loop and outputting a differential current signal corresponding to the current of the loop; a first measuring circuit connected to the output of the current sensor for receiving the differentiated current signal as an input and outputting a first digital current signal corresponding to the current of the loop when the differentiated current signal is not higher than a first predetermined value; a second measurement circuit connected to the output of the current sensor for receiving the differentiated current signal as an input and outputting a second digital current signal corresponding to the current of the loop when the differentiated current signal is above the first predetermined value; and a processing and communication circuit, connected to the first and second measuring circuits, for receiving as input the first and second digital current signals, determining a first characteristic value corresponding to the current of the loop from the first or second digital current signal when the circuit breaker is open, and sending the determined first characteristic value to an external device, wherein the first measuring circuit includes a voltage clamp circuit therein, and the voltage clamp circuit is connected to the output of the current sensor, and when the differential current signal is higher than a second predetermined value, the voltage clamp circuit clamps the differential current signal, and the second predetermined value is greater than or equal to the first predetermined value.
Optionally, the voltage clamp circuit includes a first diode, a second diode, and a first resistor, a cathode of the first diode is connected to an anode of the second diode, an anode of the first diode is grounded, a cathode of the second diode is connected to a bias voltage, a sum of the bias voltage and a forward voltage drop of the second diode is equal to the second predetermined value, one end of the first resistor is connected to the output terminal of the current sensor, the other end of the first resistor is connected to a connection point between the cathode of the first diode and the anode of the second diode, and the other end of the first resistor serves as the output terminal of the voltage clamp circuit.
Optionally, the voltage clamping circuit further comprises: the voltage clamping circuit comprises a first diode, a second diode, a first capacitor and a second capacitor, wherein one end of the second diode is connected to a connection point between the cathode of the first diode and the anode of the second diode, the other end of the second diode is used as the output end of the voltage clamping circuit, one end of the first capacitor is connected to the output end of the current sensor, one end of the second capacitor is connected to the other end of the second diode, and the other ends of the first capacitor and the second capacitor are both grounded.
Optionally, the measuring device further comprises a transient voltage suppressor connected to the output of the current sensor for protecting the measuring device in the presence of a surge current.
Optionally, the first measurement circuit further comprises a first analog-to-digital converter and a first current integrator, an input of the first analog-to-digital converter is connected to the output of the voltage clamping circuit, an output of the first analog-to-digital converter is connected to the input of the first current integrator, an output of the first current integrator is connected to the processing and communication circuit, the first analog-to-digital converter performs analog-to-digital conversion on the differential current signal to output an analog-to-digital converted differential current signal when the differential current signal is not higher than the first predetermined value, and the first current integrator integrates the analog-to-digital converted differential current signal to output the first digital current signal; the second measurement circuit comprises a second current integrator and a second analog-to-digital converter, an input of the second current integrator being connected to the output of the current sensor, an output of the second current integrator being connected to an input of the second analog-to-digital converter, an output of the second analog-to-digital converter being connected to the processing and communication circuit, the second current integrator integrating the differentiated current signal to output an analog signal corresponding to the current of the loop, the second analog-to-digital converter analog-to-digital converting the analog signal to output the second digital current signal corresponding to the current of the loop when the differentiated current signal is higher than the first predetermined value.
Optionally, the second current integrator is a resistive-capacitive integrating circuit.
Optionally, the first current integrator, the second analogue to digital converter and the processing and communication circuitry are located in the same microprocessor.
Optionally, the measuring device further comprises a power supply circuit providing the power required by the measuring device.
Optionally, the power circuit includes an energy storage capacitor to enable the measurement device to perform emergency operations using power stored by the capacitor when the circuit breaker is de-energized.
Optionally, the measuring device further comprises: a contact state information acquisition circuit associated with the auxiliary contacts, the trip indicating contacts, and the fault indicating contacts of the circuit breaker to acquire state information on the contacts, and the processing and communication circuit transmits the acquired state information to an external device when the circuit breaker is broken.
Optionally, the measuring device further comprises: the voltage detection circuit is connected to a wire outlet end of the circuit breaker and used for detecting the voltage of the detected loop, and the third analog-to-digital converter is used for converting the detected voltage into a digital voltage signal corresponding to the voltage of the loop; wherein the processing and communication circuit determines a second characteristic value related to the current and/or voltage of the circuit from the digital current signal and/or the digital voltage signal when the circuit breaker is not open and transmits the second characteristic value to an external device.
Optionally, the current sensor comprises a rogowski coil.
Optionally, the first characteristic value indicates one of the following causes of the circuit breaker breaking: no failure, overload and short circuit.
Optionally, the second characteristic value is indicative of at least one of: an effective value of the voltage, an effective value of the current, a power value related to the voltage and the current, an energy value, and total harmonic distortion information.
The technical scheme of the utility model beneficial effect lie in providing a measuring device as circuit breaker annex, can measure the electric current on a large scale in the circuit of circuit breaker through the device, except normal operating current, can also measure the great overload current of amplitude and short-circuit current, in case the circuit breaker opens circuit, can be used for judging the eigenvalue of the reason that opens circuit according to the current determination that real-time measurement arrived to send external equipment with the eigenvalue as the basis of investigation circuit fault for the maintainer.
Drawings
These and/or other aspects, features and advantages of the present invention will become more apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, which relate only to some embodiments of the invention and are not limiting thereof, wherein:
fig. 1 shows a schematic view of a usage scenario of a measuring device according to an embodiment of the present invention;
fig. 2 shows a schematic structural diagram of a measuring device according to an embodiment of the present invention;
FIG. 3 further illustrates a circuit schematic of the voltage clamp circuit of FIG. 2;
FIG. 4 further illustrates a schematic diagram of the first and second measurement circuits of FIG. 2; and
fig. 5 shows another schematic structural view of a measuring device according to the invention.
Detailed Description
The present invention will be described in detail below with reference to exemplary embodiments thereof. The invention is not limited to the embodiments described herein, however, which may be embodied in many different forms. The described embodiments are intended only to be exhaustive and complete, and to fully convey the concept of the invention to those skilled in the art. Features of the various embodiments described may be combined with each other or substituted for each other unless expressly excluded or otherwise excluded in context.
In the embodiments of the present invention, unless otherwise specifically stated, "connected" does not mean that "directly connected" or "directly in contact" is necessary, but only needs to be electrically connected.
Fig. 1 shows a schematic view of a usage scenario of a measurement apparatus according to an embodiment of the present invention.
As shown in fig. 1, the circuit breaker, the measuring device and the load according to the embodiment of the present invention are connected in the power supply network, and the measuring device 10 can be connected at the outlet of the circuit breaker as an accessory of the circuit breaker, so as to measure the current in the loop where the circuit breaker is located. The circuit breaker is triggered to trip to break the circuit of the circuit breaker when a manual switch-on button, a leakage test button are pressed down, overload or short-circuit current appears in the circuit and the like. The measuring device can measure the current value of a loop where the breaker is located in real time, including normal working current and fault current, and can judge the reason for breaking the breaker according to the measured current value when the breaker breaks so as to help maintenance personnel to remove faults.
Fig. 2 shows a schematic structural diagram of the measuring device 10 according to an embodiment of the present invention.
Referring to fig. 2, the measurement device 10 includes a current sensor 110, a first measurement circuit 120, a second measurement circuit 130, and a processing and communication circuit 140.
The current sensor 110 is connected to the outlet of the circuit breaker, senses the current I of the measured loop, and outputs a differential current signal diff (I) corresponding to the current I of the loop. The current I can include both normal operating current and fault current, and therefore, the measurement range is large. The current sensor 110 may be any current sensor capable of sensing a wide range of currents, such as a Rogowski Coil (Rogowski Coil), which has no magnetic core and no saturation phenomenon, and is uniquely advantageous for large current measurement. The output of the current sensor 110 is a differential current signal diff (I) corresponding to the current I of the loop, which is a voltage proportional to the differential of the current I of the loop under test. Specifically, when the input end of the current sensor 110 inputs the current I of the measured loop, the output end will output a differentiated current signal diff (I) ═ M dI/dt, where M is the mutual inductance of the current sensor 110 and dI/dt is the differential of the current I of the measured loop.
The first measurement circuit 120 is coupled to the output of the current sensor 110 for receiving as input the differentiated current signal diff (I) when the differentiated current signal diff (I) is not higher than the first predetermined value V1Time-output first digital current signal I corresponding to current I of tested loopD1. A second measuring circuit 130 is connected to the output of the current sensor 110 for receiving as input a differentiated current signal diff (i) when the differentiated current signal diff (i) is higher than a first predetermined value V1Time-output second digital current signal I corresponding to current I of the tested loopD2. That is, the differential current signal diff (I) is simultaneously inputted to the first measuring circuit 120 and the second measuring circuit 130, and the first measuring circuit 120 does not exceed the first predetermined value V when the differential current signal diff (I) is not higher than the first predetermined value V1Time-output first digital current signal ID1At a differential current signalNumber diff (I) higher than a first predetermined value V1A signal corresponding to the current I of the circuit under test is not output. The second measurement circuit 130 is arranged to measure the differential current signal diff (I) above a first predetermined value V1Time-out second digital current signal ID2And when the differential current signal diff (I) is not higher than the first predetermined value V1A signal corresponding to the current I of the circuit under test is not output at all, as will be described in detail below. First predetermined value V1May be the maximum value that the circuit under test may cause during normal operation. In other words, the first measurement circuit 120 is used to measure the normal operating current.
When the differentiated current signal diff (i) is large, e.g. above the second predetermined value V2, it is possible to damage the elements in the first measurement circuit 120, for which purpose the first measurement circuit 120 may comprise a voltage clamp circuit 121. The input of the voltage clamp 121 is connected to the output of the current sensor 110 when the differential current signal diff (I) is higher than a second predetermined value V2While the voltage clamp circuit 121 clamps the differential current signal diff (I), wherein the second predetermined value V2Is greater than or equal to a first predetermined value V1But not enough to damage the voltage values of the circuit elements in the first measurement circuit 120. The voltage clamp circuit 121 will be described in detail below in conjunction with fig. 3.
The processing and communication circuit 140 is connected to the first measurement circuit 120 and the second measurement circuit 130 for receiving the first digital current signal ID1And a second digital current signal ID2As input, when the circuit breaker is open, according to the first digital current signal ID1Or the second digital current signal ID2A first characteristic value corresponding to the current I of the loop is determined (e.g., determined by way of calculation). In particular, when the circuit breaker is open, if the differential current signal diff (I) is not higher than the first predetermined value V1The first measurement circuit 120 outputs a first digital current signal ID1The processing and communication circuit 140 is based on the first digital current signal ID1Determining a first characteristic value; if the differentiated current signal diff (I) is higher than the first predetermined value V1The second measuring circuit outputs a second digital current signal ID2Processing and communication circuit140 according to the second digital current signal ID2A first feature value is determined. The first characteristic value may be any value that may help indicate the cause of the circuit breaker disconnection, for example, may be the value of the current I, or may be one of the causes of the circuit breaker disconnection that is determined based on the value of the current I, including but not limited to no fault, overload, and short circuit. For example, the processing and communication circuit 140 may be based on the first digital current signal ID1Or the second digital current signal ID2The value of the current I is determined, when the value does not exceed a predetermined normal operating current threshold, the cause of the circuit break is no fault (e.g., including but not limited to, causes of manual closing, a leak test button being pressed, a failure of the circuit breaker itself, etc.), when the value exceeds a predetermined overload current threshold, the cause of the circuit break is overload, and when the value exceeds a predetermined short circuit current threshold, the cause of the circuit break is short circuit. The processing and communication circuitry 140 also transmits the determined first characteristic value to an external device, such as a gateway, an external memory, an external input output device, or the like. In the present invention, the processing and communication circuit 140 can be implemented by a dedicated hardware circuit, such as FPGA, or can be implemented by a microprocessor in combination with a known program.
Therefore, according to the utility model discloses a measuring device 10 can measure the electric current on a large scale through these two passageways of first measuring circuit 120 and second measuring circuit 130, except normal operating current, can also measure great overload current and short-circuit current, in case the circuit breaker opens circuit, can be according to the first digital current signal I that real-time measurement arrivedD1Or the second digital current signal ID2And determining the value of the current I, even judging the reason of the circuit breaker breaking according to the value of the current I, and sending the determination or judgment result to external equipment, so that a sufficient basis is provided for a maintainer to check the line fault.
Fig. 3 further illustrates a circuit schematic of the voltage clamp circuit 121 of fig. 2.
Referring to fig. 3, the voltage clamp circuit 121 includes a first diode D1, a second diode D2, and a first resistor R1. The cathode of the first diode D1 is connected to the anode of the second diode D2, the anode of the first diode D1 is grounded, and the cathode of the second diode D2 is connected to a bias voltagePressure VBBBias voltage VBBAnd the sum of the forward voltage drops of the second diode D2 is equal to a second predetermined value V2. One end of the first resistor R1 is connected to the output terminal of the current sensor 110, the other end is connected to a connection point between the cathode of the first diode D1 and the anode of the second diode D2, and the other end of the first resistor R1 serves as an output terminal Out1 of the voltage clamp circuit 121.
When the differential current signal diff (I) inputted to the first measuring circuit 120 is higher than the second predetermined value V2When the current I is a short-circuit current, for example, due to a short circuit in the tested loop, the differential current signal diff (I) will be clamped to the bias voltage V via the first resistor R1 and the second diode D2BB. The voltage output from the output terminal Out1 will not exceed the bias voltage VBBAnd the sum of the forward voltage drop of the second diode D2, i.e. a second predetermined value V2. In other words, in this case, the current generated by the differential current signal diff (i) is drained through the first resistor R1 and the second diode D2 without damaging the subsequent element from the output terminal Out 1.
The presence of the first diode D1 prevents damage to the first measurement circuit when the short circuit current is a reverse current. The first diode D1 will be turned on when the short-circuit current is reverse current, and the current generated by the differential current signal diff (i) is discharged through the first resistor R1 and the first diode D1 without damaging the following elements from the output terminal Out 1.
Therefore, under the action of the voltage clamp circuit 120, when the differential current signal diff (I) of the loop to be detected is higher than the second predetermined value V2In this case, the first measurement circuit 120 is not damaged, but the first measurement circuit 120 can no longer detect the loop current, i.e. the first measurement circuit 120 will not output a signal corresponding to the current I of the loop to be measured, and the current at this time will be detected by the second measurement circuit 130.
Further, in some examples, the voltage clamp circuit 121 may further include a second resistor R2, a first capacitor C1, and a second capacitor C2. The first capacitor C1 and the second capacitor C2 are used as filter capacitors, and can filter high-frequency interference on a circuit. One end of the second resistor R2 is connected to a connection point between the cathode of the first diode D1 and the anode of the second diode D2, and the other end of the second resistor R2 serves as an output terminal Out1 of the voltage clamp circuit 121. The second resistor R2 is used to further reduce the current output from the output terminal Out1 to protect other components in the first measurement circuit 120.
In addition, in consideration of the inrush current phenomenon, the current I of the measured loop may be a very large inrush current, and the differential current signal diff (I) output from the current sensor is too large, which may damage the measuring device 10. Therefore, the measurement device 10 may further include a protection element against an inrush current. Still referring to fig. 3, the measurement device 110 may further include a transient voltage suppressor EC1 having one end connected to the output terminal of the current sensor 110 and the other end connected to the reference voltage Vref，VrefMay be designed according to conventional experience, for example, 1/2 designed to be 0 volts or supply voltage, and the present invention is not limited in this respect. When the current I of the loop under test is an inrush current, the transient voltage suppressor EC1 clamps the differential current signal diff (I) so that the differential current signal diff (I) input to the first measurement circuit 120 and the second measurement circuit 130 will be equal to the clamping voltage of the transient voltage suppressor, which may be designed to have a voltage value that does not damage other components in the measurement apparatus 10 but exceeds the detection range of the first measurement circuit 120 and the second measurement circuit 130.
Fig. 4 further shows a schematic diagram of the first measurement circuit 120 and the second measurement circuit 130 in fig. 2.
Referring to fig. 4, the first measurement circuit 120 includes a first analog-to-digital converter (ADC)122 and a first current integrator 123 in addition to the voltage clamping circuit 121. The detection range of the first measurement circuit 120 may depend on the detection range of the first ADC 122. The first measuring circuit 120 is used to measure the normal operating current, the first predetermined value V, according to the description above in connection with fig. 21May be the maximum value that the circuit under test may cause during normal operation. In other words, the first predetermined value V1May be the maximum value of the detection range of the first ADC 122.
The input of the first ADC122 is connected to the output of the voltage clamp 121An output terminal Out1, an output terminal of the first ADC122 being coupled to an input terminal of a first current integrator 123, an output terminal of the first current integrator 123 being coupled to the processing and communication circuit 140, when the differentiated current signal diff (i) is not higher than a first predetermined value V1While the first ADC122 performs an analog-to-digital conversion on the differential current signal diff (I) to output an analog-to-digital converted differential current signal, the first current integrator integrates the analog-to-digital converted differential current signal to output a first digital current signal ID1。
Specifically, when the current signal diff (I) is not higher than the first predetermined value V1Due to the first predetermined value V1Less than a second predetermined value V2The second diode D2 in the voltage clamp circuit 121 is not turned on while the impedance of the first resistor R1 is much smaller than the impedance of the first ADC, the differentiated current signal diff (I) is input to the first ADC122, the first ADC122 performs analog-to-digital conversion on the differentiated current signal diff (I), outputs an analog-to-digital converted differentiated current signal diff (I) ', and then the first current integrator integrates the analog-to-digital converted differentiated current signal diff (I)' and outputs the first digital current signal ID1. When the current signal diff (I) is higher than the second predetermined value V2At this time, the second diode D2 in the voltage clamp circuit 121 is turned on, and the voltage inputted to the first ADC122 is clamped to the second predetermined value V2So that the first ADC does not output a signal corresponding to the current I of the loop under test. When the differential current signal diff (I) is higher than the first predetermined value V1But not higher than a second predetermined value V2Although the differential current signal diff (i) is not clamped, the maximum value of the detection range of the first ADC122 is the first predetermined value V1The differential current signal diff (I) is also not correctly converted by the first ADC, and thus the first ADC does not output a signal corresponding to the current I of the loop under test.
The second measurement circuit 130 comprises a second current integrator 131 and a second ADC132, the input of the second current integrator 131 being connected to the output of the current sensor 110, the output of the second current integrator 131 Out2 being connected to the input of the second ADC132, the output of the second ADC132 being connected to the processing and communication circuit 140, the second current integrator 131 being paired with a differential current integrator 131The divided current signal diff (I) is integrated and outputs an analog current signal I' corresponding to the current I of the loop, which is analog-to-digital converted by the second ADC132 when the divided current signal diff (I) is higher than a first predetermined value V1Time-out of a second digital current signal I corresponding to the current I of the loopD2。
Specifically, the second current integrator 131 may be a resistance-capacitance integration circuit (also referred to as an RC integration circuit). Still referring back to fig. 3, the second current integrator 131 may be an RC integrator circuit formed by a third resistor R3 and a third capacitor C3, the output terminal Out2 of which is connected to the second ADC 132. The second current integrator 131 integrates the differentiated current signal diff (I) to output an analog signal I' at an output Out2 corresponding to the current I of the loop. Since RC integration circuits are well known to those skilled in the art, they will not be explained in detail herein. The values of the third resistor R3 and the third capacitor C3 may be designed in combination with the mutual inductance M of the current sensor 110 so that the analog signal I' is within the detection range of the second ADC132, which is not limited by the invention. It should be noted that, since the second measurement circuit 130 is designed to detect a larger signal by selecting an appropriate component, when the differential current signal diff (i) is smaller, for example, the first predetermined value V1The second measurement circuit 130 cannot perform accurate measurement because the output of the RC integrating circuit is almost negligible, so that when the differential current signal diff (i) is not higher than the first predetermined value V1At this time, the second measurement circuit 130 does not output a signal corresponding to the loop current I.
In some embodiments, the first current integrator 123, the second ADC132, and the processing and communication circuit 140 may be located in the same Microprocessor (MCU). The microprocessor typically contains a Central Processing Unit (CPU) with computing capabilities and a communication module with communication capabilities (e.g., wired, Wi-Fi, bluetooth, etc. communication can be implemented), which may serve as the processing and communication circuitry 140. Furthermore, a digital integrator and an analog-to-digital converter are also typically integrated inside the microprocessor, so the digital integrator and the analog-to-digital converter inside the microprocessor can be used to respectively serve as the first current integrator 123 and the second ADC132, thereby saving cost and facilitating implementation.
The basic structure and operation of the measurement device 10 are described above with reference to fig. 2-4, and the protection principle of the transient voltage suppressor and voltage clamp circuit 121 on the measurement device 10 is further described with reference to fig. 2 and 3.
The current I of the loop under test may be a small normal operating current, a large short-circuit current, and a very large inrush current.
When the current I of the tested loop is a small normal working current, i.e. the differential current signal diff (I) is not higher than the first predetermined value V1When the transient voltage suppressor is not turned on, the differential current signal diff (i) is input to the first measurement circuit 120 and the second measurement circuit 130. For the first measurement circuit 120, the differential current signal diff (I) is not higher than the first predetermined value V1Must not be higher than the second predetermined value V2The second diode in the first measurement circuit 120 is not turned on, and the differentiated current signal diff (I) becomes the first digital current signal I after being converted by the first ADC and the first current integratorD1. With the second measurement circuit 130, although the differential current signal diff (I) is also input to the second measurement circuit 130, the output at the output terminal Out2 after forming the integration circuit through R3 and C3 is almost negligible (for example, the voltage output from the output terminal Out2 is smaller than the detection sensitivity of the second ADC), so that the second ADC may not have an output, at least, a signal corresponding to the current I of the loop. In this case, the processing and communication circuit 140 is based on the first digital current signal ID1A first characteristic value is determined and transmitted.
When the current I of the loop to be measured is a large short-circuit current, i.e. the differential current signal diff (I) is higher than the first predetermined value V1But below the turn-on voltage of the transient voltage suppressor, the differentiated current signal diff (i) is input to the first measurement circuit 120 and the second measurement circuit 130. For the second measurement circuit 130, the differentiated current signal diff (I) is converted into a second digital current signal I after the second current integrator and the second ADCD2. And for the first measurement circuit 120, when the differentiated current signal diff (I) is higher than the second predetermined value V2When the second diode D2 is turned on, the voltage input to the first ADC122 is clamped to a second predetermined value V2Since the detection range of the first ADC122 does not exceed the first predetermined value V1So that the first ADC does not output a signal corresponding to the current I of the loop under test; when the differential current signal diff (I) is higher than the first predetermined value V1And is lower than a second predetermined value V2Although the differential current signal diff (I) is not clamped, the detection range of the first ADC122 does not exceed the first predetermined value V1The differential current signal diff (I) is also not correctly converted by the first ADC, and thus the first ADC does not output a signal corresponding to the current I of the loop under test. In this case, the processing and communication circuit 140 determines and transmits the first characteristic value from the second digital current signal ID 2.
When the current I of the loop under test is a very large inrush current, the transient voltage suppressor is turned on and clamps the differential current signal diff (I). The voltage input to the first and second measurement circuits 120 and 130 is equal to a clamping voltage of the transient voltage suppressor, which may be designed to a voltage value satisfying the following condition: (1) other components in the measurement apparatus 10 are not damaged, (2) the voltage output from the output terminal Out1 after passing through the voltage clamp circuit 121 exceeds the detection range of the first ADC, and (3) the voltage output from the output terminal Out2 after passing through the second current integrator exceeds the detection range of the second ADC, so that the first ADC and the second ADC may output significantly abnormal values but are not damaged.
Thus, by protecting the measuring device 10 by the transient voltage suppressor and the voltage clamp circuit 121, the measuring device 10 can measure both the normal operation current and the fault current without being affected by the inrush current.
In some examples, the measurement device 10 may also include a power circuit (not shown in the figures) to provide the power required by the measurement device 10. The power supply circuit may comprise an energy storage capacitor to enable the measuring device 10 to perform emergency operations using the power stored by the energy storage capacitor when the circuit breaker is open, e.g. saving important data such as the first characteristic value to an internal memory (not shown in the figures) or sending it by the processing and communication circuit 140 to an external device (e.g. a gateway or an external input output device). It should be noted that the measuring device 10 may also be powered by an external power source, which is not limited by the present invention.
In some examples, the measurement device 10 may further include a contact state information acquisition circuit (not shown in the figures) that may be associated with a plurality OF contacts OF the circuit breaker, such as auxiliary contacts (OF), trip indicating contacts (SD), and fault indicating contacts (SDE), to acquire state information about the contacts. For example, the status information may be a bit string having several bits, each bit representing a status OF one OF the contacts, e.g., a bit OF 1 associated with the auxiliary contact (OF) indicates that the circuit breaker is in an open state, a bit OF 0 indicates that the circuit breaker is in a closed state, a bit OF 1 associated with the trip indication contact (SD) indicates that the circuit breaker is tripped due to the leakage point test button being pressed, a bit OF 0 indicates that the circuit breaker is tripped due to other reasons, a bit OF 1 associated with the fault indication contact (SDE) indicates that the circuit breaker is tripped due to a fault, and a bit OF 0 indicates that the circuit breaker is tripped due to other reasons. The processing and communication circuit 140 also sends the acquired status information to the external device when the circuit breaker is open, whereby both the first characteristic value and the status information of the circuit breaker contacts are sent to the maintenance personnel, providing the maintenance personnel with sufficient information to determine the cause of the fault. The use of the processing and communication circuitry 140 of the measurement device 10 to transmit the status information also avoids the need for additional communication circuitry or power circuitry, saving costs.
Fig. 5 shows a schematic view of another configuration of a measuring device according to the invention.
Referring to fig. 5, in comparison to fig. 1, the measurement apparatus 10 may further include a voltage detection circuit 150 and a third ADC 160. The voltage detection circuit 150 is used for connecting to the outlet terminal of the circuit breaker and detecting the voltage U of the detected loop. For example, the voltage detection circuit 150 may be a resistive voltage divider circuit to scale the voltage U to be within the detection range of the third ADC. The third ADC160 is used for converting the voltage U (or the scaled voltage U) into a digital voltage signal U corresponding to the voltage UD. Thus, the measuring device 10 may be used when the circuit breaker is not openDetects the voltage U and the current I and is based on the first digital current signal ID1A second digital current signal ID2And/or digital voltage signal UDA second characteristic value relating to the current I and/or the voltage U of the measured circuit is determined (for example, by calculation) and transmitted to the external device. The second characteristic value may include an effective value of the voltage U, an effective value of the current I, a power value P related to the voltage U and the current I, an energy value E, and/or Total Harmonic Distortion (THD) information, etc. It is noted that although the third ADC is shown in fig. 5 as a different ADC from the first ADC, the third ADC may be the same ADC as the first ADC if the detection range allows it.
According to the utility model discloses measuring device 10 of this embodiment can measure voltage and electric current in the return circuit of circuit breaker place in real time to obtain corresponding digital voltage signal and digital current signal. When the circuit breaker is not opened, the effective value of the voltage, the effective value of the current, the power and energy information and/or the total harmonic distortion information in the voltage and the current can be determined based on the digital voltage signal and the digital current signal; when the circuit breaker is broken, the reason for breaking the circuit breaker, including at least one of no fault, overload, and short circuit, can be judged based on the digital voltage signal and the digital current signal. The measuring device 10 can also send these determinations to an external device for maintenance personnel to use as a basis for troubleshooting.
The block diagrams of circuits, devices, apparatus, devices, and systems presented herein are meant to be illustrative examples only and are not intended to require or imply that the blocks, devices, and systems shown in the block diagrams must be connected or arranged or configured in a manner consistent with the teachings of the block diagrams. As will be appreciated by one skilled in the art, these circuits, devices, apparatus, devices, systems may be connected, arranged, configured in any manner that achieves the intended purposes.
It should be understood by those skilled in the art that the foregoing specific embodiments are merely exemplary and not limiting, and that various modifications, combinations, sub-combinations and substitutions may be made in the embodiments of the invention depending upon design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
Claims (14)
1. A measuring device, characterized by comprising:
the current sensor is used for being connected with a wire outlet end of the circuit breaker, sensing the current of a detected loop and outputting a differential current signal corresponding to the current of the loop;
a first measuring circuit connected to the output of the current sensor for receiving the differentiated current signal as an input and outputting a first digital current signal corresponding to the current of the loop when the differentiated current signal is not higher than a first predetermined value;
a second measurement circuit connected to the output of the current sensor for receiving the differentiated current signal as an input and outputting a second digital current signal corresponding to the current of the loop when the differentiated current signal is above the first predetermined value; and
a processing and communication circuit, connected to said first and second measuring circuits, for receiving as input said first and second digital current signals, determining a first characteristic value corresponding to the current of said circuit from said first or second digital current signal when said circuit breaker is open, and sending said determined first characteristic value to an external device,
the first measuring circuit comprises a voltage clamping circuit, the voltage clamping circuit is connected to the output end of the current sensor, when the differential current signal is higher than a second preset value, the voltage clamping circuit clamps the differential current signal, and the second preset value is larger than or equal to the first preset value.
2. The measurement device of claim 1, wherein:
the voltage clamping circuit comprises a first diode, a second diode and a first resistor,
the cathode of the first diode is connected with the anode of the second diode, the anode of the first diode is grounded, the cathode of the second diode is connected with a bias voltage, the sum of the bias voltage and the forward voltage drop of the second diode is equal to the second preset value,
one end of the first resistor is connected to an output terminal of the current sensor, the other end is connected to a connection point between a cathode of the first diode and an anode of the second diode, and the other end of the first resistor serves as an output terminal of the voltage clamp circuit.
3. A measuring device as claimed in claim 2, characterized in that:
the voltage clamping circuit further comprises a second resistor, a first capacitor and a second capacitor,
one end of the second resistor is connected to a connection point between the cathode of the first diode and the anode of the second diode, and the other end of the second resistor serves as an output terminal of the voltage clamp circuit,
one end of the first capacitor is connected to the output end of the current sensor, one end of the second capacitor is connected to the other end of the second resistor, and the other ends of the first capacitor and the second capacitor are both grounded.
4. The measurement device of claim 1, further comprising:
a transient voltage suppressor connected to the output of the current sensor for protecting the measuring device in the presence of a surge current.
5. The measurement device of any one of claims 1-4, wherein:
the first measurement circuit further comprises a first analog-to-digital converter and a first current integrator, an input of the first analog-to-digital converter is connected to the output of the voltage clamp circuit, an output of the first analog-to-digital converter is connected to the input of the first current integrator, an output of the first current integrator is connected to the processing and communication circuit, the first analog-to-digital converter analog-to-digital converts the differentiated current signal to output an analog-to-digital converted differentiated current signal when the differentiated current signal is not higher than the first predetermined value, the first current integrator integrates the analog-to-digital converted differentiated current signal to output the first digital current signal;
the second measurement circuit comprises a second current integrator and a second analog-to-digital converter, an input of the second current integrator being connected to the output of the current sensor, an output of the second current integrator being connected to an input of the second analog-to-digital converter, an output of the second analog-to-digital converter being connected to the processing and communication circuit, the second current integrator integrating the differentiated current signal to output an analog signal corresponding to the current of the loop, the second analog-to-digital converter analog-to-digital converting the analog signal to output the second digital current signal corresponding to the current of the loop when the differentiated current signal is higher than the first predetermined value.
6. The measurement device of claim 5, wherein:
the second current integrator is a resistive-capacitive integrating circuit.
7. The measurement device of claim 5, wherein:
the first current integrator, the second analog-to-digital converter and the processing and communication circuit are located in the same microprocessor.
8. The measurement device according to any one of claims 1-4, further comprising:
and the power supply circuit provides power required by the measuring device.
9. The measurement device of claim 8, wherein:
the power circuit includes an energy storage capacitor to enable the measurement device to utilize the power stored by the capacitor to complete emergency operations when the circuit breaker is de-energized.
10. The measurement device according to any one of claims 1-4, further comprising:
a contact state information acquisition circuit associated with the auxiliary contacts, the trip indicating contacts and the fault indicating contacts of the circuit breaker to acquire state information on the contacts, and
the processing and communication circuit transmits the acquired status information to an external device when the circuit breaker is tripped.
11. The measurement device according to any one of claims 1-4, further comprising:
the voltage detection circuit is used for being connected to a wire outlet end of the circuit breaker and detecting the voltage of the detected loop; and the number of the first and second groups,
a third analog-to-digital converter for converting the detected voltage into a digital voltage signal corresponding to the voltage of the loop; wherein
The processing and communication circuit determines a second characteristic value related to the current and/or voltage of the circuit from the digital current signal and/or the digital voltage signal when the circuit breaker is not open and transmits the second characteristic value to an external device.
12. The measurement device of any one of claims 1-4, wherein:
the current sensor includes a rogowski coil.
13. The measurement device of any one of claims 1-4, wherein:
the first characteristic value indicates one of the following causes of the circuit breaker breaking: no failure, overload and short circuit.
14. The measurement device of claim 11, wherein:
the second characteristic value is indicative of at least one of: an effective value of the voltage, an effective value of the current, a power value related to the voltage and the current, an energy value, and total harmonic distortion information.
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|---|---|---|---|
| CN202120365468.6U CN215219064U (en) | 2021-02-09 | 2021-02-09 | Measuring device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120365468.6U CN215219064U (en) | 2021-02-09 | 2021-02-09 | Measuring device |
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| CN215219064U true CN215219064U (en) | 2021-12-17 |
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