CN211741546U - Secondary side state detection circuit of current transformer, fire alarm device and electric energy meter - Google Patents
Secondary side state detection circuit of current transformer, fire alarm device and electric energy meter Download PDFInfo
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- CN211741546U CN211741546U CN202020078322.9U CN202020078322U CN211741546U CN 211741546 U CN211741546 U CN 211741546U CN 202020078322 U CN202020078322 U CN 202020078322U CN 211741546 U CN211741546 U CN 211741546U
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Abstract
The utility model discloses a current transformer secondary side state detection circuitry, fire alarm device, electric energy meter, wherein current transformer secondary side state detection circuitry, including control module, sampling module, first filter module and second filter module, wherein control module is used for receiving the control signal that outside measurement judgement module sent, still is used for sending detection signal to sampling module according to the control signal; the sampling module is used for receiving the detection signal and generating a first detection voltage signal and a second detection voltage signal according to the detection signal, the sampling module sends the first detection voltage signal to the external metering judgment module after passing through the first filtering module, the second detection voltage signal is sent to the external metering judgment module after passing through the second filtering module, and the external metering judgment module judges the state of a secondary side winding of the current transformer. The utility model discloses the components and parts that adopt are few, and are small, and manufacturing cost and maintenance cost are low.
Description
Technical Field
The utility model relates to a circuit detection area especially relates to a current transformer secondary side state detection circuitry, fire alarm device, electric energy meter.
Background
The current transformer is widely applied to detection circuits, comprises a current transformer for power supply detection, is used for providing power grid current information for measurement and metering devices in a normal voltage range, and also comprises a current transformer for protection, and is used for providing power grid fault current information for devices such as relay protection and the like in a power grid fault state.
Because the number of turns of the primary side winding of the current transformer is small, the turn ratio of the secondary side winding is high, and the secondary side winding is connected in series in a measuring instrument and a protection loop, the current transformer and secondary side equipment can be damaged when the secondary side winding fails.
For example, in patent application CN106786366A, the prior art uses a complex circuit with an operational amplifier circuit to detect open-circuit and short-circuit faults of the secondary winding, which is a secondary side open-circuit protection and early-warning system for current transformers, and has high cost and large volume, so that further improvement is needed.
SUMMERY OF THE UTILITY MODEL
The utility model discloses to the shortcoming among the prior art, provide a current transformer secondary side state detection circuit, fire alarm device, electric energy meter.
In order to solve the technical problem, the utility model discloses a following technical scheme can solve:
a secondary side state detection circuit of a current transformer is respectively coupled with a secondary side winding and a metering judgment module of an external current transformer and comprises a control module, a sampling module, a first filtering module and a second filtering module, wherein the sampling module is respectively coupled with the control module, the first filtering module, the second filtering module and the secondary side winding of the external current transformer; the control module, the first filtering module and the second filtering module are all coupled with an external metering judgment module;
the control module is used for receiving a control signal sent by an external metering judgment module and sending a detection signal to the sampling module according to the control signal;
the sampling module is used for receiving the detection signal and generating a first detection voltage signal and a second detection voltage signal according to the detection signal, the sampling module sends the first detection voltage signal to the external metering judgment module after passing through the first filtering module, the second detection voltage signal is sent to the external metering judgment module after passing through the second filtering module, and the external metering judgment module judges the state of a secondary side winding of the current transformer.
As an implementable embodiment:
the control module comprises a control signal input end, a voltage output end and a switch circuit, wherein the switch circuit is respectively coupled with the control signal input end, the voltage input end and the voltage output end;
the control signal input end is used for receiving a control signal sent by an external metering judgment module;
the switch circuit is used for controlling the conduction of the voltage input end and the voltage output end according to the control signal, and when the voltage input end is conducted with the voltage output end, the voltage output end outputs a voltage signal to the sampling module to serve as a detection signal.
As an implementable embodiment:
the switching circuit comprises a first biasing resistor, a second biasing resistor and a triode, wherein the triode is a PNP type triode;
the emitting electrode of the triode is coupled with the voltage input end and is also coupled with the base electrode of the triode through a first bias resistor;
the base electrode of the triode is also coupled with the input end of the control signal through a second biasing resistor;
and the collector of the triode is coupled with the voltage output end.
As an implementable embodiment:
the sampling module comprises a first sampling resistor and a second sampling resistor which are connected in series;
the second sampling resistor is connected with a secondary side winding of an external current transformer in parallel to form a parallel branch;
one end of the parallel branch is coupled with the control module through a first sampling resistor and is also coupled with an external metering judgment module through a first filtering module, and the other end of the parallel branch is coupled with the external metering judgment module through a second filtering module.
As an implementable embodiment:
and the first filtering module and the second filtering module both adopt resistance-capacitance filtering circuits.
As an implementable embodiment:
the input signal protection module is connected with two ends of a secondary side winding of the external current transformer in parallel and is composed of two diodes which are connected in parallel in an opposite direction.
The utility model also provides a fire alarm device, including residual current transformer, measurement judgment module and alarm module, wherein measurement judgment module and alarm module are coupled, and the primary side winding of residual current transformer is used for gathering the residual current, and the secondary side winding is used for generating corresponding induced-current; the device further comprises a state detection circuit, wherein the state detection circuit is coupled with the secondary side winding and the metering judgment module respectively.
As an implementable embodiment:
the metering judgment module is used for controlling the state detection circuit to output an induced voltage signal of the induced current or outputting a detection voltage signal for detecting the state of the secondary side winding;
the metering judgment module is also used for generating a residual current value according to the induction voltage signal and controlling the alarm module to alarm according to the residual current value;
the metering judgment module is also used for determining the state of the secondary side winding according to the detection voltage signal and controlling the alarm module to alarm according to the state.
As an implementable embodiment:
the metering judgment module comprises a single chip microcomputer and a metering chip, wherein the single chip microcomputer is respectively coupled with the metering chip, the control state detection circuit and the alarm module, and the metering chip is also coupled with the control state detection circuit;
the single chip microcomputer is used for acquiring an induced voltage signal or a detection voltage signal output by the state detection circuit through a metering chip, generating a residual current value according to the induced voltage signal and judging the state of the secondary side winding according to the detection voltage signal;
the single chip microcomputer is also used for controlling an alarm module to give an alarm according to the residual current value or the state of the secondary side winding.
The utility model also provides an electric energy meter, including alarm module, singlechip and measurement chip, wherein the singlechip is coupled with alarm module and measurement chip respectively, still includes residual current transformer and above-mentioned arbitrary one state detection circuit, state detection circuit is coupled with residual current transformer, singlechip and measurement chip respectively.
As an implementable embodiment:
the primary side winding of the residual current transformer is used for collecting residual current, and the secondary side winding of the residual current transformer is used for generating corresponding induced current;
the single chip microcomputer is used for acquiring an induced voltage signal or a detection voltage signal output by the state detection circuit through a metering chip, generating a residual current value according to the induced voltage signal and judging the state of the secondary side winding according to the detection voltage signal;
the single chip microcomputer is also used for controlling an alarm module to give an alarm according to the residual current value or the state of the secondary side winding.
The utility model discloses owing to adopted above technical scheme, have apparent technological effect:
1. the utility model discloses to the design of state detection circuit, can realize the state detection to the secondary side winding through less components and parts, can effectively reduce detection cost low and maintenance cost; compared with the existing state detection circuit, the circuit has smaller volume and is convenient to integrate into the existing device which needs to detect the state of the secondary side winding.
2. The utility model discloses a to the design of first filtering module and second filtering module, make its and measurement judge the module cooperation and detect, detect the precision and reach 200mA in addition.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic diagram of a module connection of a secondary side state detection circuit of a current transformer according to the present invention;
fig. 2 is a schematic circuit connection diagram of the control module 110 in embodiment 1;
fig. 3 is a circuit schematic diagram of a secondary side state detection circuit of the current transformer in embodiment 1;
fig. 4 is a schematic diagram of the connection of the modules for fire alarm in the fire alarm device (or electric energy meter).
In the figure, 110 is a control module, 120 is a sampling module, 130 is a first filtering module, 140 is a second filtering module, 150 is an input signal protection module, 200 is a metering judgment module, 210 is a single chip microcomputer, 220 is a metering chip, 300 is a current transformer, and 400 is an alarm module.
Detailed Description
The present invention will be described in further detail with reference to the following examples, which are illustrative of the present invention and are not intended to limit the present invention.
Embodiment 1, a current transformer secondary side state detection circuit, as shown in fig. 1, is composed of a control module 110, a sampling module 120, a first filtering module 130, a second filtering module 140, and an input signal protection module 150, where the sampling module 120 is respectively coupled to the control module 110, the first filtering module 130, the second filtering module 140, the input signal protection module 150, and a secondary side winding of an external current transformer 300, where the input signal protection module 150 is connected in parallel to two ends of the secondary side winding, and the control module 110, the first filtering module 130, and the second filtering module 140 are all coupled to an external metering judgment module 200.
The control module 110 is configured to receive a control signal sent by an external metering determination module 200, and is further configured to send a detection signal to the sampling module 120 according to the control signal;
referring to fig. 2, the control module 110 includes a control signal input terminal, a voltage output terminal, and a switch circuit, wherein the switch circuit is coupled to the control signal input terminal, the voltage input terminal, and the voltage output terminal, respectively, the control signal input terminal is coupled to an external metering judgment module 200, and the voltage output terminal is coupled to the sampling module 120;
the control signal input end is used for receiving a control signal sent by an external metering judgment module 200;
the switch circuit is configured to control the voltage input end to be conducted with the voltage output end according to the control signal, and when the voltage input end is conducted with the voltage output end, the voltage output end outputs a voltage signal to the sampling module 120 as a detection signal.
When the voltage input terminal and the voltage output terminal are not conducted, the voltage output terminal cannot form a current loop with the sampling module 120 through the switch circuit, and the normal alternating current signal cannot be influenced.
The switch circuit is composed of a first bias resistor RN6, a first bias resistor RN7 and a triode QN1, wherein the triode QN1 is a PNP type triode;
the emitter of the transistor QN1 is coupled to the voltage input terminal, and is also coupled to the base thereof through a first bias resistor RN 6;
the base of the transistor QN1 is also coupled to the control signal input terminal through a first bias resistor RN 7;
the collector of the transistor QN1 is coupled to the voltage output.
The first bias resistor RN6 and the first bias resistor RN7 form a bias circuit of the transistor QN1, and provide a stable static operating voltage for the transistor QN1, so that the transistor QN1 is in a stable state;
in this embodiment, when the external measurement and determination module 200 outputs a control signal (as shown in CTT in fig. 2) to the control signal input terminal, the control signal pulls low the high level at the base of the transistor QN1 to turn on the transistor QN1, and the voltage input terminal outputs a voltage signal as a detection signal to the voltage output terminal through the transistor QN 1.
The sampling module 120 is configured to receive the detection signal, generate a first detection voltage signal and a second detection voltage signal according to the detection signal, the sampling module 120 sends the first detection voltage signal to the external metering determination module 200 after passing through the first filtering module 130, sends the second detection voltage signal to the external metering determination module 200 after passing through the second filtering module 140, and determines the state of the secondary winding of the current transformer 300 by the external metering determination module 200.
Referring to fig. 3, the sampling module 120 includes a first sampling resistor RN3 and a first sampling resistor RN4 connected in series, and the first sampling resistor RN3 and the first sampling resistor RN4 constitute a proportional voltage divider circuit for dividing the detection signal;
the first sampling resistor RN4 is connected in parallel with the secondary side winding of the external current transformer 300 to form a parallel branch;
one end of the parallel branch is coupled to the voltage output terminal through a first sampling resistor RN3, and is further coupled to the external metering and judging module 200 through a first filtering module 130, and the other end of the parallel branch is coupled to the external metering and judging module 200 through a second filtering module 140.
Note that the parallel branch is also in parallel with the input signal protection.
When the external metering judgment module 200 outputs a control signal to the control signal input end, the triode QN1 is turned on, at this time, the voltage input end, the first sampling resistor RN3 and the first sampling resistor RN4 form a current loop, at this time, the voltage signal input by the voltage input end is divided in proportion, the external metering judgment module 200 samples the voltage at two ends of the first sampling resistor RN4 through the first filtering module 130 and the second filtering module 140, the obtained voltage signal is used as a detection voltage signal, and the state of the secondary side winding is judged based on the detection voltage signal. The states include short, open, and normal.
When the external metering judgment module 200 prohibits the control signal from being output to the control signal input terminal, the triode QN1 is turned off, the voltage input terminal, the first sampling resistor RN3 and the first sampling resistor RN4 cannot perform a current loop at this time, the induced current generated by the secondary winding is converted into a voltage signal by the first sampling resistor RN4 at this time, the external metering judgment module 200 samples the voltage at the two ends of the first sampling resistor RN4 through the first filtering module 130 and the second filtering module 140, the obtained voltage signal is used as an induced voltage signal, and the residual current value is calculated based on the induced voltage signal.
The induced voltage signal includes a first detected voltage signal (shown as IN N IN fig. 3) filtered by the first filtering module 130 and a second detected voltage signal (shown as IN P IN fig. 3) filtered by the second filtering module 140, and the external metering and determining module 200 can obtain the amplitude of the divided voltage of the first sampling resistor RN4 through the first detected voltage signal and the second detected voltage signal, so as to determine the state of the secondary winding according to the amplitude.
The metering judgment module 200 judges the state of the secondary side winding as follows:
a person skilled in the art can set a maximum threshold value and a minimum threshold value according to the voltage input by the voltage input terminal and the resistance values of the first sampling resistor RN3 and the first sampling resistor RN4, and perform state detection when no induced current is generated in the secondary winding, that is, the metering and determining module 200 sends out a control signal;
when the voltage value at the two ends of the first sampling resistor RN4 is detected to exceed the maximum threshold value, the state of the secondary side winding is judged to be an open circuit;
when the voltage value at two ends of the first sampling resistor RN4 is detected to be smaller than the minimum threshold value, judging that the state of the secondary side winding is short circuit;
when the voltage value at the two ends of the first sampling resistor RN4 is detected to be between the maximum threshold value and the minimum threshold value (including the maximum threshold value and the minimum threshold value), the state of the secondary side winding is determined to be normal.
In the present embodiment, the design of the sampling module 120 avoids the problem of damage to the external metering and determining module 200 due to a large current generated by a short circuit of the secondary winding during the state detection process.
Referring to fig. 3, the input signal protection module 150 is composed of two inverse parallel diodes, as shown by a diode DN1 and a diode DN2 in fig. 3, and is configured to ensure that the signal amplitude does not exceed the maximum input range of the external metering judgment module 200 in the event of an excessive interference signal, so as to avoid causing damage to the external metering judgment module 200.
Referring to fig. 3, the first filtering module 130 and the second filtering module 140 both employ a resistance-capacitance filtering circuit for filtering out unwanted noise high-frequency signals to improve the measurement accuracy.
Note that in fig. 3, the resistor RN1 and the capacitor CN1 form the first filter module 130, and the resistor RN2 and the capacitor CN2 form the second filter module 140.
The state detection circuit disclosed by the embodiment can realize the state detection of the secondary side winding by only utilizing the components, and compared with the existing state detection circuit, the state detection circuit has the advantages that the number of the used components is small, the production and the manufacture are convenient, and the detection cost and the maintenance cost can be effectively reduced; compared with the existing state detection circuit, the circuit has smaller volume and is convenient to be integrated into the existing device which needs to detect the state of the secondary side winding; in the prior art, due to the noise, the precision can only reach 300mA, and if the precision needs to be improved, an operational amplifier chip with higher precision is required, so that the scheme is expensive and has no practicability, and the state detection circuit provided by the embodiment does not need to use a high-precision operational amplifier chip through the cooperation of the first filtering module 130, the second filtering module 140 and the metering judgment module 200, so that the detection precision can reach 200 mA.
Embodiment 2, a fire alarm apparatus, as shown in fig. 4, includes a current transformer 300, a metering judgment module 200, an alarm module 400, and the state detection circuit described in embodiment 1, wherein the metering judgment module 200 is coupled to the alarm module 400;
in this embodiment, the current transformer 300 employs a mutual residual current inductor, a primary winding of the mutual residual current inductor is used for collecting a residual current, and a secondary winding of the mutual residual current inductor is used for generating a corresponding induced current. The state detection circuit is coupled to the secondary winding and the metering and judging module 200, respectively.
The metering judgment module 200 is configured to control the state detection circuit to output an induced voltage signal of the induced current, or output a detection voltage signal for detecting the state of the secondary side winding;
the metering judgment module 200 is further configured to generate a residual current value according to the induced voltage signal;
the metering judgment module 200 is further configured to determine a state of the secondary side winding according to the detection voltage signal, and control the alarm module 400 to alarm according to the state.
Note:
the induced voltage signal is a voltage signal (a voltage signal after the induced current conversion) at two ends of the first sampling resistor RN4 when the metering and determining module 200 prohibits sending the control signal;
when the detection voltage signal is a control signal sent by the metering judgment module 200, the voltage value at the two ends of the first sampling resistor RN4 (the voltage signal after the detection signal is divided);
the measurement and judgment module 200 may be, for example, a central controller in an existing fire alarm device, and the alarm module 400 may be, for example, a fire alarm module 400 in an existing fire alarm device.
Further, the metering judgment module 200 includes a single chip microcomputer 210 and a metering chip 220, referring to fig. 4, wherein the single chip microcomputer 210 is coupled to the metering chip 220, the control state detection circuit and the alarm module 400, the metering chip 220 is further coupled to the control state detection circuit, specifically, the single chip microcomputer 210 is coupled to the control signal input terminal, and the metering chip 220 is coupled to the first filtering module 130 and the second filtering module 140;
the single chip microcomputer 210 is configured to collect an induced voltage signal or a detected voltage signal output by the state detection circuit through the metering chip 220, generate a residual current value according to the induced voltage signal, and determine the state of the secondary side winding according to the detected voltage signal;
the single chip microcomputer 210 is further configured to control the alarm module 400 to alarm according to the residual current value or the state of the secondary side winding, specifically:
when the residual current value exceeds a preset alarm current threshold value, the single chip microcomputer 210 controls the alarm module 400 to alarm;
when the state of the secondary side winding is open circuit or short circuit, the single chip microcomputer 210 controls the alarm module 400 to alarm.
The metering chip 220 can also be used to monitor the power supply conditions of the power supply network, such as overvoltage, undervoltage, overcurrent, electrical load, etc., which are applied in the prior art and therefore will not be described in detail.
In this embodiment, the metering chip 220 may be, for example, the metering chip 220 with the model CS5460A, and the single chip microcomputer 210 may be, for example, the single chip microcomputer 210 with the model AT89C 51.
Embodiment 3 is an electric energy meter, including an alarm module 400, a single chip microcomputer 210, a metering chip 220, a current transformer 300, and the state detection circuit described in embodiment 1, where the single chip microcomputer 210 is coupled to the alarm module 400 and the metering chip 220, respectively, and the state detection circuit is coupled to the current transformer 300, the single chip microcomputer 210, and the metering chip 220, respectively.
Note that the alarm module 400, the single chip microcomputer 210, and the metering chip 220 are all modules/chips of an existing electric energy meter, and the current transformer 300 is a residual current transformer.
The primary side winding of the residual current mutual inductance is used for collecting residual current, and the secondary side winding is used for generating corresponding induced current;
the single chip microcomputer 210 is configured to collect an induced voltage signal or a detected voltage signal output by the state detection circuit through the metering chip 220, generate a residual current value according to the induced voltage signal, and determine the state of the secondary side winding according to the detected voltage signal;
the single chip microcomputer 210 is further configured to control the alarm module 400 to alarm according to the state of the secondary side winding.
The specific work content of the electric energy meter for fire alarm in the embodiment is as follows:
1. the single chip microcomputer 210 prohibits sending a control signal to the state detection circuit;
a primary side winding of the residual current mutual inductance collects residual current, and a secondary side winding generates corresponding induced current;
a triode QN1 in the state detection circuit is in a cut-off state, the induction current and the first sampling resistor RN4 form a current loop, and the first sampling resistor RN4 converts the induction current into a voltage signal;
the metering chip 220 acquires voltage signals at two ends of the first sampling resistor RN4 through the first filtering module 130 and the second filtering module 140 to obtain an induced voltage signal, and sends the induced voltage signal to the single chip microcomputer 210, and the single chip microcomputer 210 calculates a residual current value according to the induced voltage signal.
The single chip microcomputer 210 judges whether the residual current value is greater than a preset alarm current threshold value, and if the residual current value is greater than the preset alarm current threshold value, the alarm module 400 is controlled to alarm for a fire alarm.
The one-chip microcomputer 210 judges whether the remaining current value is 0, and if not, the one-chip microcomputer 210 keeps the work of detecting the remaining current value.
2. The single chip microcomputer 210 judges whether the residual current value is 0, if not, the single chip microcomputer 210 keeps working for detecting the residual current value, otherwise, the single chip microcomputer 210 detects the working state of the secondary side winding.
When the remaining current value is 0, the single chip microcomputer 210 sends a control signal to the state detection circuit, at this time, a triode QN1 in the state detection circuit is in a conducting state, and the input voltage end outputs a detection signal to the sampling module 120 through the output voltage end;
since the residual current value is 0 at this time, that is, no induced current is generated in the secondary winding, the detection signal is divided by the first sampling resistor RN3 and the first sampling resistor RN4 in the sampling module 120;
the metering chip 220 acquires voltage signals at two ends of the first sampling resistor RN4 through the first filtering module 130 and the second filtering module 140 to obtain detection voltage signals, and sends the detection voltage signals to the single chip microcomputer 210, and the single chip microcomputer 210 calculates according to the detection voltage signals to obtain voltage amplitude values.
The single chip microcomputer 210 compares the obtained voltage amplitude with a preset maximum threshold value and a preset minimum threshold value:
when the voltage amplitude exceeds the maximum threshold value, the state of the secondary side winding is judged to be open circuit, and the alarm module 400 is controlled to alarm;
when the voltage amplitude is smaller than the minimum threshold value, the state of the secondary side winding is judged to be open circuit, and the alarm module 400 is controlled to alarm;
when the voltage amplitude is between the maximum threshold and the minimum threshold (including the maximum threshold and the minimum threshold), it is determined that the state of the secondary winding is normal, and the single chip microcomputer 210 stops sending the control signal to the state detection circuit and continues detecting the remaining current value.
The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
It should be noted that:
reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase "one embodiment" or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.
While the preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the appended claims be interpreted as including the preferred embodiment and all such alterations and modifications as fall within the scope of the invention.
In addition, it should be noted that names and the like of components of the specific embodiments described in the present specification may be different. All equivalent or simple changes made according to the structure, characteristics and principle of the utility model are included in the protection scope of the utility model. Various modifications, additions and substitutions may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.
Claims (10)
1. A secondary side state detection circuit of a current transformer is respectively coupled with a secondary side winding of an external current transformer and a metering judgment module, and is characterized by comprising a control module, a sampling module, a first filtering module and a second filtering module, wherein the sampling module is respectively coupled with the control module, the first filtering module, the second filtering module and the secondary side winding of the external current transformer; the control module, the first filtering module and the second filtering module are all coupled with an external metering judgment module;
the control module is used for receiving a control signal sent by an external metering judgment module and sending a detection signal to the sampling module according to the control signal;
the sampling module is used for receiving the detection signal and generating a first detection voltage signal and a second detection voltage signal according to the detection signal, the sampling module sends the first detection voltage signal to the external metering judgment module after passing through the first filtering module, the second detection voltage signal is sent to the external metering judgment module after passing through the second filtering module, and the external metering judgment module judges the state of a secondary side winding of the current transformer.
2. The current transformer secondary side state detection circuit according to claim 1, characterized in that:
the control module comprises a control signal input end, a voltage output end and a switch circuit, wherein the switch circuit is respectively coupled with the control signal input end, the voltage input end and the voltage output end;
the control signal input end is used for receiving a control signal sent by an external metering judgment module;
the switch circuit is used for controlling the conduction of the voltage input end and the voltage output end according to the control signal, and when the voltage input end is conducted with the voltage output end, the voltage output end outputs a voltage signal to the sampling module to serve as a detection signal.
3. The current transformer secondary side state detection circuit according to claim 2, characterized in that:
the switching circuit comprises a first biasing resistor, a second biasing resistor and a triode, wherein the triode is a PNP type triode;
the emitting electrode of the triode is coupled with the voltage input end and is also coupled with the base electrode of the triode through a first bias resistor;
the base electrode of the triode is also coupled with the input end of the control signal through a second biasing resistor;
and the collector of the triode is coupled with the voltage output end.
4. The current transformer secondary side state detection circuit according to claim 1, characterized in that:
the sampling module comprises a first sampling resistor and a second sampling resistor which are connected in series;
the second sampling resistor is connected with a secondary side winding of an external current transformer in parallel to form a parallel branch;
one end of the parallel branch is coupled with the control module through a first sampling resistor and is also coupled with an external metering judgment module through a first filtering module, and the other end of the parallel branch is coupled with the external metering judgment module through a second filtering module.
5. The current transformer secondary side state detection circuit according to claim 1, characterized in that:
and the first filtering module and the second filtering module both adopt resistance-capacitance filtering circuits.
6. The current transformer secondary side state detection circuit according to claim 1, characterized in that:
the input signal protection module is connected with two ends of a secondary side winding of the external current transformer in parallel and is composed of two diodes which are connected in parallel in an opposite direction.
7. A fire alarm device comprises a residual current transformer, a metering judgment module and an alarm module, wherein the metering judgment module is coupled with the alarm module, a primary side winding of the residual current transformer is used for collecting residual current, and a secondary side winding of the residual current transformer is used for generating corresponding induced current; the secondary side winding state detection circuit is characterized by further comprising a state detection circuit according to any one of claims 1 to 6, wherein the state detection circuit is respectively coupled with the secondary side winding and the metering judgment module.
8. The fire alarm apparatus according to claim 7, wherein:
the metering judgment module is used for controlling the state detection circuit to output an induced voltage signal of the induced current or outputting a detection voltage signal for detecting the state of the secondary side winding;
the metering judgment module is also used for generating a residual current value according to the induction voltage signal and controlling the alarm module to alarm according to the residual current value;
the metering judgment module is also used for determining the state of the secondary side winding according to the detection voltage signal and controlling the alarm module to alarm according to the state.
9. An electric energy meter comprises an alarm module, a single chip microcomputer and a metering chip, wherein the single chip microcomputer is respectively coupled with the alarm module and the metering chip, and the electric energy meter is characterized by further comprising a residual current transformer and a state detection circuit according to any one of claims 1 to 6, wherein the state detection circuit is respectively coupled with the residual current transformer, the single chip microcomputer and the metering chip.
10. The electrical energy meter of claim 9, wherein:
the primary side winding of the residual current transformer is used for collecting residual current, and the secondary side winding of the residual current transformer is used for generating corresponding induced current;
the single chip microcomputer is used for acquiring an induced voltage signal or a detection voltage signal output by the state detection circuit through a metering chip, generating a residual current value according to the induced voltage signal and judging the state of the secondary side winding according to the detection voltage signal;
the single chip microcomputer is also used for controlling an alarm module to give an alarm according to the residual current value or the state of the secondary side winding.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111060864A (en) * | 2020-01-14 | 2020-04-24 | 杭州海兴电力科技股份有限公司 | Secondary side state detection circuit of current transformer, fire alarm device and electric energy meter |
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2020
- 2020-01-14 CN CN202020078322.9U patent/CN211741546U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111060864A (en) * | 2020-01-14 | 2020-04-24 | 杭州海兴电力科技股份有限公司 | Secondary side state detection circuit of current transformer, fire alarm device and electric energy meter |
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