CN217882827U - Electric energy meter and protection circuit of external relay thereof - Google Patents
Electric energy meter and protection circuit of external relay thereof Download PDFInfo
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- CN217882827U CN217882827U CN202222125129.8U CN202222125129U CN217882827U CN 217882827 U CN217882827 U CN 217882827U CN 202222125129 U CN202222125129 U CN 202222125129U CN 217882827 U CN217882827 U CN 217882827U
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Abstract
The utility model provides an electric energy meter and a protection circuit of an external relay thereof.A first auxiliary terminal of the electric energy meter is connected with a fourth end of the external relay through an overcurrent protection unit; the third end of the external relay is connected with the second auxiliary terminal of the electric energy meter; a switch is arranged between the third end and the fourth end of the external relay; the first end of the external relay is connected with the power supply circuit through the impedance unit, and a rectifying unit is arranged between the first end and the second end of the external relay; the control end of the switch unit is used as the switching-off control end of the electric energy meter; the circuit of the external relay of the electric energy meter is reformed, and when the current of the circuit is suddenly overlarge, the circuit can be protected, so that the circuit cannot be broken and cannot work; that is, an overcurrent protection unit is added in a circuit of an external relay of the electric energy meter, so that the circuit is protected, and the shunt release is prevented from being burnt and the circuit is broken due to sudden increase of current or wrong wiring.
Description
Technical Field
The utility model belongs to the technical field of the protection circuit, more specifically the theory that says so especially relates to an electric energy meter and external relay's protection circuit.
Background
The existing external relay circuit is connected with the shunt release, and at the moment when the shunt release is switched on, the shunt release is possibly subjected to extremely high current, so that the shunt release is burnt out, a circuit is broken, and the shunt release cannot work. Or improper wiring of a user, which causes the current of the user to flow through the coil of the shunt release for a long time, can also cause the shunt release to be burnt.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model aims to provide an electric energy meter and external relay's protection circuit thereof for add the overcurrent protection unit in the circuit through the external relay of electric energy meter, realize protecting the circuit, prevent that the electric current from increasing suddenly, perhaps wrong wiring leads to shunt release to burn out, the circuit opens circuit.
The application first aspect discloses a protection circuit of external relay in electric energy meter, includes: the overcurrent protection unit, the rectification unit, the impedance unit and the switch unit;
the first end of the overcurrent protection unit is connected with a first auxiliary terminal of the electric energy meter;
the second end of the overcurrent protection unit is connected with the fourth end of the external relay;
the third end of the external relay is connected with the second auxiliary terminal of the electric energy meter;
a switch is arranged between the third end and the fourth end of the external relay;
the first end of the external relay is respectively connected with one end of the impedance unit and the output end of the rectifying unit;
the second end of the external relay is respectively connected with the input end of the rectifying unit and the first end of the switch unit;
the second end of the switch unit is grounded;
the other end of the impedance unit is connected with a power supply circuit;
and the control end of the switch unit is used as the switching-off control end of the electric energy meter.
Optionally, in the protection circuit of the external relay in the electric energy meter, the resistance value of the overcurrent protection unit is in direct proportion to the current of the external relay;
when the current of the external relay is larger than the maximum current which can be borne by the overcurrent protection unit, the overcurrent protection unit is in an open circuit state, and the current loop of the external relay is disconnected.
Optionally, in the protection circuit of an external relay in the electric energy meter, the overcurrent protection unit includes: at least one thermistor.
Optionally, in the protection circuit of the external relay in the electric energy meter, the overcurrent protection unit further includes: short-circuit bonding pads;
the short-circuit bonding pad is connected with the thermistor in parallel.
Optionally, in the protection circuit of the external relay in the electric energy meter, the impedance unit includes: at least one first resistor.
Optionally, in the protection circuit of the external relay in the electric energy meter, the number of the first resistors of the impedance unit is 2, and the first resistors are connected in parallel.
Optionally, in the protection circuit of an external relay in the electric energy meter, the rectifying unit includes: a rectifier diode;
the anode of the rectifying diode is used as the input end of the rectifying unit;
and the cathode of the rectifying diode is used as the output end of the rectifying unit.
Optionally, in the protection circuit of an external relay in the electric energy meter, the switch unit includes: the switch tube, the third resistor and the second resistor;
the first end of the second resistor is connected with the first end of the third resistor, and the connecting point is connected with the control end of the switching tube;
a second end of the second resistor is used as a control end of the switch unit;
the first end of the switch tube is used as the first end of the switch unit;
and the second end of the switch tube is connected with the second end of the third resistor, and the connection point is used as the second end of the switch unit.
Optionally, in the protection circuit of the external relay in the electric energy meter, the switching tube is a triode.
The second aspect of the present application discloses an electric energy meter, including: a chip, an external relay and a protection circuit as described in any one of the first aspect of the present application;
when the electric energy meter is switched off, the chip outputs a conducting signal to a control end of a switch unit in the protection circuit so as to conduct the switch unit;
the protection circuit is used for protecting the electric energy meter.
According to the above technical scheme, the utility model provides a pair of external relay's protection circuit, include: the overcurrent protection unit, the rectification unit, the impedance unit and the switch unit; the first end of the overcurrent protection unit is connected with a first auxiliary terminal of the electric energy meter; the second end of the overcurrent protection unit is connected with the fourth end of the external relay; the third end of the external relay is connected with the second auxiliary terminal of the electric energy meter; a switch is arranged between the third end and the fourth end of the external relay; the first end of the external relay is respectively connected with one end of the impedance unit and the output end of the rectifying unit; the second end of the external relay is respectively connected with the input end of the rectifying unit and the first end of the switch unit; the second end of the switch unit is grounded; the other end of the impedance unit is connected with the power supply circuit; the control end of the switch unit is used as the switching-off control end of the electric energy meter; the circuit of the external relay of the electric energy meter is reformed, and when the current of the circuit is suddenly overlarge, the circuit can be protected, so that the circuit cannot be broken and cannot work; that is, through adding overcurrent protection unit in the circuit of the external relay of electric energy meter, realize protecting the circuit, prevent that the electric current from increasing suddenly, perhaps wrong wiring, lead to shunt release burning out, circuit open circuit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are 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 protection circuit of an external relay according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a protection circuit of another external relay according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a protection circuit of another external relay according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a protection circuit of another external relay according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a protection circuit of another external relay according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a protection circuit of another external relay according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a protection circuit of another external relay according to an embodiment of the present invention;
fig. 8 is a schematic diagram of signal transmission of an electric energy meter structure according to an embodiment of the present invention;
fig. 9 is a schematic diagram of connection of an electric energy meter according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
The embodiment of the application provides a protection circuit of external relay in electric energy meter for external relay circuit connection shunt release among the solution prior art, in the twinkling of an eye that this shunt release switches on, can have very big electric current, causes shunt release to burn out, and the circuit opens circuit, can't work. Or improper wiring of a user causes current of the user to flow through a coil of the shunt release for a long time, and the shunt release is burnt.
It should be noted that, as shown in fig. 9, a live wire inlet of the electric energy meter is connected to a live wire of the commercial power; a live wire outlet of the electric energy meter is respectively connected with a first auxiliary terminal (an auxiliary terminal 2 shown in fig. 9) of the electric energy meter and a fifth end 5 of the shunt release; the zero line inlet of the electric energy meter is connected with the zero line of the commercial power; a zero line outlet of the electric energy meter is connected with a third end 3 of the shunt release; a second auxiliary terminal (an auxiliary terminal 3 shown in fig. 9) of the electric energy meter is connected with the first end 1 of the shunt release; the second end 2 of the shunt release is connected with the fourth end 4 of the shunt release; the sixth section 6 of the shunt release is connected to the consumer load or other external line.
The electric energy meter can be matched with the shunt release to conduct and break control on user loads or external lines.
Referring to fig. 1, comprising: the overcurrent protection unit 100, the rectifying unit 300, the impedance unit 500, and the switching unit 400.
A first end of the overcurrent protection unit 100 is connected with a first auxiliary terminal 11 of the electric energy meter; the second end of the overcurrent protection unit 100 is connected with the fourth end 4 of the external relay 200; the third terminal 3 of the external relay 200 is connected with the second auxiliary terminal 12 of the electric energy meter.
That is, the external relay 200 is not directly connected to the utility power; but the overcurrent protection unit 100 is connected to the utility power, and when the external relay 200 is improperly connected or the current is too high, the external relay 200 or even the electric energy meter can be protected by the overcurrent protection unit 100.
A switch is arranged between the third terminal 3 and the fourth terminal 4 of the external relay 200.
For convenience of description, a switch between the third end 3 and the fourth end 4 of the external relay 200 is named as a relay switch, and the name is also used in the following description, which is not described in detail below as the switch disposed between the third end 3 and the fourth end 4 of the external relay 200.
The relay switch is normally open, that is, the external relay 200 is normally open between the third terminal 3 and the fourth terminal 4.
Therefore, when the electric energy meter normally works, namely the electric energy meter is switched on, the relay switch is in a normally open state.
Specifically, when the current of the auxiliary terminal of the electric energy meter is small, the overcurrent protection unit 100 performs a protection action; when the current of the auxiliary terminal of the electric energy meter is large, the overcurrent protection unit 100 performs a protection action; it should be noted that the protection action may have two or more levels of protection, and is not specifically limited herein, and all of the protection actions are within the protection scope of the present application, as the case may be.
The following description takes two-stage protection as an example:
the primary protection is that when the current of the auxiliary terminal of the electric energy meter is within the range which can be borne by the overcurrent protection unit 100, the overcurrent protection unit 100 limits the current of the auxiliary terminal of the electric energy meter; the current is avoided too much, and specifically, the resistance value can be adjusted according to the current of the auxiliary terminal of the electric energy meter to avoid the current of the auxiliary terminal of the electric energy meter from being too great.
The secondary protection is that the current of the auxiliary terminal of the electric energy meter exceeds the range which can be borne by the overcurrent protection unit 100, and the overcurrent protection unit 100 is disconnected, so that the connection between the electric energy meter and the mains supply is disconnected, and the electric energy meter is prevented from being damaged.
The protection action of the over-current protection unit 100 may also be in other levels, or in other manners, which is not described herein any more, and is within the protection scope of the present application depending on the actual situation.
The first end 1 of the external relay 200 is respectively connected with one end of the impedance unit 500 and the output end of the rectifying unit 300; the other end of the impedance unit 500 is connected to the power supply circuit VHH.
That is, the external relay 200 is connected to the power supply circuit VHH through the impedance unit 500, in other words, the power supply circuit VHH supplies power to the external relay 200 through the impedance unit 500.
The resistance value of the impedance unit 500 can be selected according to the working voltage of the external relay 200 and the voltage of the power supply circuit VHH, which is not described herein any more, and is determined according to the actual situation, all within the protection scope of the present application.
The second end 2 of the external relay 200 is respectively connected with the input end of the rectifying unit 300 and the first end of the switching unit 400;
the second terminal of the switching unit 400 is grounded.
It should be noted that the current at the input end of the rectifying unit 300 can flow to the output end of the rectifying unit 300, but the current at the output end of the rectifying unit 300 cannot flow to the input end of the rectifying unit 300. That is, the rectifying unit 300 is unidirectional or not bidirectional.
The specific type of the rectifying unit 300 is not described herein, and is within the scope of the present application.
The control terminal of the switch unit 400 serves as a switching control terminal of the electric energy meter.
That is, the switching-off signal received at the switching-off control terminal of the electric energy meter and the signal received at the control terminal of the switch unit 400 both represent the same content; that is, when the pull-off signal indicates that the pull-off is required, the switch unit 400 performs the corresponding pull-off operation.
The specific switching-off operation may be that the switch unit 400 is in a conducting state, or the like, or may be in other manners, which is not described herein any more, and is within the protection scope of the present application depending on the actual situation.
In the present embodiment, a first end of the overcurrent protection unit 100 is connected to the first auxiliary terminal 11 of the electric energy meter; the second end of the overcurrent protection unit 100 is connected with the fourth end 4 of the external relay 200; the third end 3 of the external relay 200 is connected with the second auxiliary terminal 12 of the electric energy meter; a switch is arranged between the third end 3 and the fourth end 4 of the external relay 200; the first end 1 of the external relay 200 is respectively connected with one end of the impedance unit 500 and the output end of the rectifying unit 300; the second end 2 of the external relay 200 is respectively connected with the input end of the rectifying unit 300 and the first end of the switching unit 400; the second terminal of the switching unit 400 is grounded; the other end of the impedance unit 500 is connected to the power supply circuit VHH; the control end of the switch unit 400 is used as the switching control end of the electric energy meter; the circuit of the external relay 200 of the electric energy meter is reformed, and when the current of the circuit is suddenly overlarge, the circuit can be protected, so that the circuit cannot be broken and cannot work; that is, by adding the overcurrent protection unit 100 in the circuit of the external relay 200 of the electric energy meter, the circuit is protected, and the shunt release is prevented from being burnt and the circuit is prevented from being broken due to sudden increase of current or wrong wiring.
In practical applications, the resistance of the overcurrent protection unit 100 is proportional to the current of the external relay 200.
That is to say, when the current of the external relay 200 is larger, the resistance value of the overcurrent protection unit 100 is larger, the current of the external relay 200 is reduced, and the electric energy meter is prevented from being damaged due to the overlarge current of the external relay 200.
When the current of the external relay 200 is larger than the maximum current that the overcurrent protection unit 100 can bear, the overcurrent protection unit 100 is in an open circuit state, and the current loop of the external relay 200 is disconnected.
The open circuit state can be realized by burning out, and certainly, the open circuit of the overcurrent protection unit can also be controlled by the on-off of the switch.
Specifically, taking an example that the overcurrent protection unit realizes the open circuit by burning, if the current of the external relay 200 is greater than the maximum current that the overcurrent protection unit 100 can bear, the overcurrent protection unit 100 will burn out and cannot work normally; the external relay 200 can no longer receive mains current.
When the shunt release does not operate, the resistance value of the overcurrent protection unit 100 is substantially 60 Ω to 120 Ω, and no influence is caused on the circuit. However, when the separation release acts and a circuit needs to be disconnected, the normally open switch between the third end 3 and the fourth end 4 of the external relay 200 is closed, the shunt release is turned on within less than 1S, current flows through the control circuit of the shunt release within the short time, and since the current allowed by the shunt release is small, if too large current flows through the coil, the coil is easily fused, the shunt release is damaged, and the switch cannot be pulled according to the normal control circuit, so that the external relay 200 is connected with the overcurrent protection unit 100 in series to play a good current limiting role to protect the shunt release. When a user has improper wiring, for example, a wire coming out of the 2 end of the shunt release in fig. 9 is connected to the front of the 3 end, a current always flows through a control loop of the shunt release, when the overcurrent protection unit 100 is connected in series in a circuit of the external relay 300, the temperature of the circuit is raised due to an excessive current, and then the resistance value of the circuit is increased, so that the current of the circuit is reduced, the shunt release is not damaged, if the current exceeds the range that the overcurrent protection unit 100 can bear, the overcurrent protection unit 100 is burnt, the circuit is disconnected, and the maintenance cost is lower than that of the whole external relay.
In practical applications, referring to fig. 2, the over-current protection unit 100 may include: at least one thermistor PTC.
The thermistor PTC may be a positive thermistor PTC, i.e. the thermistor PTC is a PCT resistor. Of course, other schemes are not excluded, and are not described herein any more, and all are within the scope of the present application, depending on the actual situation.
When the number of the thermistors PTC is 1 (as shown in fig. 2), both ends of the thermistors PTC serve as both ends of the overcurrent protection unit 100 (as shown in fig. 2).
When the number of the thermistors PTC is plural, each thermistor PTC is connected in series or in parallel (not shown).
The number and connection relationship of the thermistors PTC are not described in detail herein, and are within the protection scope of the present application.
The selection of the type of the thermistor PTC is not described herein, and is within the scope of the present application.
In practical applications, referring to fig. 3, the overcurrent protection unit 100 further includes: shorting pad S4.
The shorting pad S4 is connected in parallel with the thermistor PTC.
Whether to switch on the thermistor PTC can be realized by controlling the state of the shorting pad S4. Specifically, when the short-circuit bonding pad S4 is closed, the thermistor PTC is short-circuited, namely the thermistor PTC is cut off; when the shorting pad S4 is opened, the thermistor PTC is connected into the line.
In practical applications, referring to fig. 4, the impedance unit 500 includes at least one first resistor R1.
Specifically, the number of the first resistors R1 may be 1; two ends of the first resistor R1 are respectively used as two ends of the impedance unit 500; that is, one end of the first resistor R1 is connected to the power supply circuit VHH as one end of the impedance unit 500, and the other end of the first resistor R1 is connected to the first end 1 of the external relay 200 and the output terminal of the rectifying unit 300 as the other end of the impedance unit 500.
The resistance value of the first resistor R1 can be determined according to the voltage of the power supply circuit VHH and the working voltage of the external relay 200, and is not repeated here any more, and is determined according to the actual situation, and is all within the protection range of the present application.
The number of the first resistors R1 may be multiple, and two ends of each of the first resistors R1 connected in parallel are respectively used as two ends of the impedance unit 500; that is, one end of each of the first resistors R1 connected in parallel is connected to the power supply circuit VHH as one end of the impedance unit 500, and the other end of each of the first resistors R1 connected in parallel is connected to the first end 1 of the external relay 200 and the output end of the rectifying unit 300 as the other end of the impedance unit 500.
In practical applications, the number of the first resistors R1 of the impedance unit 500 may be 2 (as shown in fig. 4), and the first resistors R1 are connected in parallel.
The number of the first resistors R1 in the impedance unit 500 is not described in detail herein, and is within the protection scope of the present application depending on the actual situation.
In practical applications, referring to fig. 5, the rectifying unit 300 includes: a rectifier diode M7;
the anode of the rectifying diode M7 serves as the input terminal of the rectifying unit 300; the cathode of the rectifying diode M7 serves as the output terminal of the rectifying unit 300.
The number of the rectifier diodes M7 may be 1, and certainly is not excluded from being multiple, which is not described herein any more, and is within the protection scope of the present application depending on the actual situation.
When the number of the rectifier diodes M7 is plural, each rectifier diode M7 may be connected in series; specifically, each rectifier diode M7 is connected in series in such a manner that the anode and the cathode of the adjacent rectifier tube are connected, and the cathode after the series connection is used as the output end of the rectifier unit 300; the serially connected anodes serve as input terminals of the rectifying unit 300.
In practical applications, referring to fig. 6, the switch unit 400 includes: the switch tube Q4, the third resistor R3 and the second resistor R2;
the first end of the second resistor R2 is connected with the first end of the third resistor R3, and the connecting point is connected with the control end of the switching tube Q4.
A second end of the second resistor R2 serves as a control end of the switch unit 400 and receives a switching-off signal; specifically, the control terminal of the switching unit 400 may be connected to a RELB pin of the chip.
A first end of the switching tube Q4 is used as a first end of the switching unit 400, and is connected to the input end of the rectifying unit 300 and the second end 2 of the external relay 200, respectively.
A second end of the switching tube Q4 is connected to a second end of the third resistor R3, and a connection point serves as a second end of the switching unit 400.
That is, when receiving the switching-off signal, the switching tube Q4 is turned on, and thus the current flows through the rectifying unit 300, and accordingly the current flows between the first terminal 1 and the second terminal 2 of the external relay 200; the electromagnetic induction in the external relay 200 establishes connection between the fourth terminal 4 and the third terminal 3 of the external relay 200, so as to control the disconnection of the external shunt release.
In practical application, the switching tube Q4 is a triode.
Specifically, the switching tube Q4 may also be a MOS tube, but is preferably a triode; the MOS tube is a voltage control element, the triode is a current control element, and when the signal voltage is low, the use of the triode is proper, the price of the MOS tube is high, and the cost of the triode is low.
Specifically, an application scenario of the protection circuit is described.
As shown in fig. 7; a fourth end 4 of the external relay J3 is respectively connected with one end of the thermistor and one end of the short-circuit bonding pad S4; a third end 3 of the external relay J3 is connected with an auxiliary terminal 3 of the electric energy meter; the other end of the thermistor PTC and the other end of the short-circuit bonding pad S4 are connected with an auxiliary terminal 2 of the electric energy meter; a first end 1 of the external relay J3 is respectively connected with a cathode of the rectifier diode M7, one end of the resistor R56 and one end of the resistor R55; the other end of the resistor R56 and the other end of the resistor R55 are both connected with the power supply circuit VHH; a second end 2 of the external relay J3 is respectively connected with the anode of the rectifier diode M7 and the first end of the triode Q4; the second end of the triode Q4 and one end of the resistor R54 are both grounded GND; the control end of the triode Q4 is respectively connected with the other end of the resistor R54 and one end of the resistor R52; the other end of the resistor R53 is connected to the RELB pin of the chip.
Specifically, pins 3 and 4 of the external relay J3 are in a normally open state, at this time, the RELB pin of the chip in the electric energy meter defaults to a low level, and the external shunt release is always off. When external relay J3 needs to be switched off, chip among the electric energy meter makes the RELB foot be the high level, triode Q4 switches on, external relay J3's 1, 2 feet have the electric current to flow through, through electromagnetic induction, external relay J3's 3, 4 feet are closed, control shunt release action, with the external circuit disconnection, this external circuit can be user load etc. no longer give unnecessary details one by one here, it can to decide according to actual conditions, all in the protection scope of this application.
It should be noted that, there is a coil between pins 1 to 2 of the external relay J3, and when pins 1 to 2 of the external relay J3 are turned on, a current flows through the coil to cause an electromagnetic induction, so that a normally open switch among pins 3 to 4 of the external relay J3 is turned off.
The type of the triode Q4 may be MMBT222AT, which is certainly not limited thereto, and is not described herein any more, and is determined according to the actual situation, and all of which are within the protection scope of the present application. Resistors R56 and R55 may be 100R/1206 resistors; the thermistor PTC can be a thermistor of MZ11-10A600-121 RM; the external relay J3 can be a relay of HF 32F/012-Z; resistor R52 may be a 1K Ω resistor; the resistor R54 may be a 10K Ω resistor. The types of the devices may be other types, which are not described in detail herein, and are all within the protection scope of the present application.
It should be noted that the auxiliary terminal 2 is the first auxiliary terminal 11 in the above description, and the auxiliary terminal 3 is the second auxiliary terminal 12 in the above description. The resistors R55 and R56 are the first resistor R1 in the above description; the resistor R52 is the second resistor R2 in the above description; the resistor R54 is the third resistor R3 in the above description; the external relay J3 is the same as the external relay 200, except for the same reference numerals.
An electric current wire (live wire of mains supply) passes through the shunt release, then two ends of the shunt release are connected to the auxiliary terminal 2 and the auxiliary terminal 3 of the electric energy meter, and when the shunt release does not work, the resistance value of the PTC (positive temperature coefficient) thermistor is basically 60-120 omega, and the circuit cannot be influenced. However, when the shunt release acts, that is, when the circuit needs to be disconnected, the normally open switch between the third end 3 and the fourth end 4 of the external relay J3 is closed, the shunt release is switched on within less than 1S, current flows through the control circuit of the shunt release within the short time, and since the allowed current of the coil of the shunt release is small, if an excessive current flows through the coil, the coil is easy to fuse, the shunt release is damaged, and the circuit cannot be normally controlled to be switched off; at the moment, a loop of the external relay is connected with a thermistor PTC with the resistance value of 60-120 omega basically in series, so that a good current limiting effect can be achieved, and the shunt release is protected. When a user has improper wiring, for example, a wire from the 2 end of the shunt release in fig. 9 is connected to the front of the 3 end, the control loop of the shunt release always has current flowing, when a thermistor PTC is connected in series in the circuit of the external relay J3, the temperature of the circuit is raised due to excessive current, and then the resistance value is increased, so that the current of the circuit is reduced, the damage of the shunt release cannot be caused, if the current exceeds the range that the thermistor PTC can bear, the thermistor PTC is burned out, the circuit is disconnected, and the maintenance cost is lower than that of the whole external relay.
The chip has two states of high level and low level, when the relay is switched off, the output of a chip pin RELB is high level, wherein the chip is an element of the electric energy meter; VHH is the supply circuit.
S4 is a short-circuit bonding pad, whether the thermistor PTC is connected or not can be selected, and R55 and R54 are connected in parallel because a single resistor cannot meet the power requirement.
The rectifier diode M7 can prevent the transistor Q4 from being damaged by the voltage of the power supply circuit VHH being 12V when the RELB pin is low and the transistor Q4 is not turned on.
Triode Q4 is controlled by the chip, and operating personnel sends the command of acting as go-between to the chip through 485 communications, and the RELB pin output high level of chip leads to triode Q4 to switch on, has the electric current between external relay J3's 1 ~ 2 pins, makes the disconnection of normally open switch 3-4 pin.
As shown in fig. 8, the signal transmission process includes:
an external communication signal-Mcu chip-RELB pin (which is a pin of Mcu chip) -Q4 triode-external relay J3-shunt release-circuit on-off.
Another embodiment of the present application provides an electric energy meter.
This electric energy meter includes: chip, external relay and protection circuit.
When the electric energy meter is switched off, the chip outputs a conducting signal to the control end of the switch unit in the protection circuit so as to conduct the switch unit.
The protection circuit is used for protecting the electric energy meter.
For details of the specific structure and the working principle of the protection circuit, reference is made to the protection circuit of the external relay in the electric energy meter provided by the embodiment, which is not described herein any more, and all that is required is within the protection scope of the present application, depending on the actual situation.
As shown in fig. 8, the process of signal transmission in the electric energy meter is as follows:
an external communication signal-Mcu chip-RELB pin (which is a pin of Mcu chip) -triode Q4-external relay J3-shunt release-circuit on-off.
Features described in the embodiments in the present specification may be replaced or combined with each other, and the same and similar portions among the embodiments may be referred to each other, and each embodiment is described with emphasis on differences from other embodiments. In particular, the system or system embodiments, which are substantially similar to the method embodiments, are described in a relatively simple manner, and reference may be made to some descriptions of the method embodiments for relevant points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement without inventive effort.
Those of skill would further appreciate that the various illustrative components and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the components and steps of the various examples have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A protection circuit of an external relay in an electric energy meter is characterized by comprising: the overcurrent protection unit, the rectification unit, the impedance unit and the switch unit;
the first end of the overcurrent protection unit is connected with a first auxiliary terminal of the electric energy meter;
the second end of the overcurrent protection unit is connected with the fourth end of the external relay;
the third end of the external relay is connected with the second auxiliary terminal of the electric energy meter;
a switch is arranged between the third end and the fourth end of the external relay;
the first end of the external relay is respectively connected with one end of the impedance unit and the output end of the rectifying unit;
the second end of the external relay is respectively connected with the input end of the rectifying unit and the first end of the switch unit;
the second end of the switch unit is grounded;
the other end of the impedance unit is connected with a power supply circuit;
and the control end of the switch unit is used as the switching-off control end of the electric energy meter.
2. The protection circuit of the external relay in the electric energy meter according to claim 1, wherein the resistance value of the over-current protection unit is in direct proportion to the current of the external relay;
when the current of the external relay is larger than the maximum current which can be borne by the overcurrent protection unit, the overcurrent protection unit is in an open circuit state, and the current loop of the external relay is disconnected.
3. The protection circuit of an external relay in an electric energy meter according to claim 1, wherein the overcurrent protection unit comprises: at least one thermistor.
4. The protection circuit of the external relay in the electric energy meter according to claim 3, wherein the over-current protection unit further comprises: short-circuit bonding pads;
the short-circuit bonding pad is connected with the thermistor in parallel.
5. The protection circuit of an external relay in an electric energy meter according to claim 1, wherein the impedance unit comprises: at least one first resistor.
6. The protection circuit of an external relay in an electric energy meter according to claim 5, wherein the number of the first resistors of the impedance unit is 2, and each of the first resistors is connected in parallel.
7. The protection circuit of an external relay in an electric energy meter according to claim 1, wherein the rectifying unit comprises: a rectifier diode;
the anode of the rectifying diode is used as the input end of the rectifying unit;
and the cathode of the rectifying diode is used as the output end of the rectifying unit.
8. The protection circuit of an external relay in an electric energy meter according to claim 1, wherein the switching unit comprises: the switch tube, the third resistor and the second resistor;
the first end of the second resistor is connected with the first end of the third resistor, and the connecting point is connected with the control end of the switching tube;
a second end of the second resistor is used as a control end of the switch unit;
the first end of the switch tube is used as the first end of the switch unit;
and the second end of the switch tube is connected with the second end of the third resistor, and the connection point is used as the second end of the switch unit.
9. The protection circuit of an external relay in an electric energy meter according to claim 8, wherein the switch tube is a triode.
10. An electric energy meter, comprising: a chip, an external relay and a protection circuit according to any one of claims 1 to 9;
when the electric energy meter is switched off, the chip outputs a conducting signal to a control end of a switch unit in the protection circuit so as to conduct the switch unit;
the protection circuit is used for protecting the electric energy meter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222125129.8U CN217882827U (en) | 2022-08-12 | 2022-08-12 | Electric energy meter and protection circuit of external relay thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222125129.8U CN217882827U (en) | 2022-08-12 | 2022-08-12 | Electric energy meter and protection circuit of external relay thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN217882827U true CN217882827U (en) | 2022-11-22 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202222125129.8U Active CN217882827U (en) | 2022-08-12 | 2022-08-12 | Electric energy meter and protection circuit of external relay thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN217882827U (en) |
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2022
- 2022-08-12 CN CN202222125129.8U patent/CN217882827U/en active Active
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