CN108288846B - Optical coupler input protection circuit and protection method thereof - Google Patents
Optical coupler input protection circuit and protection method thereof Download PDFInfo
- Publication number
- CN108288846B CN108288846B CN201710013160.3A CN201710013160A CN108288846B CN 108288846 B CN108288846 B CN 108288846B CN 201710013160 A CN201710013160 A CN 201710013160A CN 108288846 B CN108288846 B CN 108288846B
- Authority
- CN
- China
- Prior art keywords
- signal input
- protection circuit
- optocoupler
- input
- port
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/06—Details with automatic reconnection
- H02H3/066—Reconnection being a consequence of eliminating the fault which caused disconnection
Landscapes
- Electronic Switches (AREA)
Abstract
The application discloses an optocoupler input protection circuit and a protection method thereof, wherein the optocoupler input protection circuit comprises a signal input unit, an input protection circuit and an optocoupler, wherein the signal input unit is sequentially connected with the input protection circuit and the optocoupler; the IN ports of the signal input units are respectively connected with photoelectric couplers, and diodes are arranged IN a photoelectric coupling input loop to cut off reverse high voltage; a self-recovery fuse is connected in series between the COM port of the signal input unit and the internal circuit; the IN ports of the signal input units are connected to the internal common terminal COM1 through diodes, respectively. The optical coupling input protection circuit is used for protecting the control panel and realizing the self-recovery of the circuit function after the abnormal signal is cancelled according to the working condition that a user is mistakenly connected with active high voltage (AC/DC) in a signal input unit on site, thereby effectively reducing the damage of the control panel caused by the wrong wiring on site and the loss of time and economy caused by the damage.
Description
Technical Field
The application relates to the technical field of circuits, in particular to an optical coupler input protection circuit and a protection method thereof.
Background
In the current common input signal detection circuit, the input signal is usually isolated by a photoelectric coupler and then transmitted into an internal circuit, so that the filtering effect on high-frequency interference signals is realized, and meanwhile, the electrical isolation among different electrical modules is realized. However, such a circuit still has a problem: if the field needs manual wiring, active/passive, when low voltage/high voltage different access signals exist, the passive or low voltage optical coupler is input to detect signal input, once the high voltage signal is accessed by mistake, the rear photoelectric coupler and the resistor are broken down and burnt, so that a new controller is likely to need to be replaced, the whole process is time-consuming and labor-consuming, and very troublesome, especially, the circuit is applied to the industrial fields like elevators, and when the personal safety problem is involved, the protection of the circuit on abnormal working conditions is very important.
In view of the above problems, it is desirable to provide an optical coupler input protection circuit and a protection method thereof, which have functions of self-protection and self-recovery of an abnormal signal and detection of a protection action.
Disclosure of Invention
In order to solve the technical problem, the application discloses an optical coupler input protection circuit and a protection method thereof.
An optical coupler input protection circuit comprises a signal input unit, an input protection circuit and an optical coupler, wherein the signal input unit is sequentially connected with the input protection circuit and the optical coupler;
the IN ports of the signal input units are respectively connected with photoelectric couplers, and diodes are arranged IN a photoelectric coupling input loop to cut off reverse high voltage;
a self-recovery fuse is connected in series between the COM port of the signal input unit and the internal circuit;
the IN ports of the signal input units are respectively connected with the internal COM1 through diodes;
furthermore, the protection circuit also comprises a protection action detection circuit, wherein the protection action detection circuit comprises a photoelectric coupler, a reverse diode and a current-limiting resistor;
further, the signal input unit is a passive signal input;
furthermore, the signal input unit comprises a plurality of signal input ports and an input public terminal interface;
furthermore, the polarity directions of the IN port of the signal input unit and a diode IN the photoelectric coupling input loop are respectively consistent with the polarity direction of the input end of the photoelectric coupler all the time;
further, the IN ports of the signal input units are connected to the internal common terminal COM1 through a diode IN a forward direction, respectively.
Further, the IN ports of the signal input units are connected to the internal common terminal COM1 through an inverted diode, respectively.
A protection method using the optocoupler input protection circuit according to claim 1, comprising:
when high voltage exists between any two ports of an IN port of the signal input unit, the whole circuit loop is not conducted at the moment because a diode for carrying out reverse protection for cutting off the high voltage is arranged IN the loop, and the corresponding photoelectric coupler does not have large current to pass through, so that the photoelectric coupler is ensured not to be burnt;
when there is a high voltage between the COM port of the signal input unit and the IN port of the signal input unit: a diode for cutting off and reversely protecting the high voltage is arranged in the loop, at the moment, the whole circuit loop is not conducted, and the corresponding photoelectric coupler has no large current, so that the photoelectric coupler is ensured not to be burnt; or, the voltage is conducted through the diode bypass to form a short circuit loop, the self-recovery fuse is broken, and the photoelectric coupler connected with the IN port has no large current to pass through, so that the photoelectric coupler is prevented from being burnt;
the protection circuit further comprises a protection action detection circuit, once the self-recovery fuse is fused, the connection from the COM port of the signal input unit to the COM1 is disconnected, a photoelectric coupler of the protection action detection circuit is not conducted, and the output end of the photoelectric coupler of the protection action detection circuit detects the jump of an output signal to prompt that the current self-recovery fuse is fused;
furthermore, when the voltage applied to the input end disappears for a period of time, the self-recovery fuse can automatically recover the low-resistance state;
furthermore, a diode of the optical coupling input protection circuit and the self-recovery fuse are both high-voltage resistant.
Compared with the prior art, the problem that maintenance is time-consuming and labor-consuming due to circuit faults caused by burning of the photoelectric coupler when a high-voltage signal is mistakenly connected to the signal input end is solved; on the other hand, because the protection action detection circuit is connected, when abnormal reverse voltage exists between the COM port and any IN port of the signal input unit, current directly forms a loop between the COM port and the corresponding IN port through the self-recovery fuse and the bypass diode, the self-recovery fuse generates self-fusing (high resistance) after passing through over-rated current, and further protects the photoelectric coupler and other internal circuits, and meanwhile, whether the current self-recovery fuse is disconnected or not can be prompted through the conduction or not of the photoelectric coupler IN the protection action detection circuit; finally, the self-healing fuse has the capability of self-healing, which reduces the number of times of product repair and service, thereby reducing the cost.
Of course, it is not necessary for any product to achieve all of the above-described technical effects simultaneously.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a conventional opto-coupler input detection circuit.
Fig. 2 is a first optical coupling input detection circuit with a protection function after the improvement of the present application.
Fig. 3 is a second optical coupling input detection circuit with a protection function after the improvement of the present application.
Detailed Description
Embodiments of the present application will be described in detail with reference to the drawings and examples, so that how to implement technical means to solve technical problems and achieve technical effects of the present application can be fully understood and implemented.
As shown in fig. 1, in a conventional optical coupler input detection circuit, an input signal is isolated by an optical coupler and then transmitted to an internal circuit, so that the filtering effect on a high-frequency interference signal is realized, and meanwhile, electrical isolation among different electrical modules is realized. However, such circuits still have problems: once a high voltage signal is introduced, the following photocoupler and resistor may be broken down and burnt, so that a new controller needs to be replaced immediately, and the whole process is troublesome and time-consuming and labor-consuming.
As shown in FIG. 2, the improved optical coupler input detection circuit with the protection function comprises a signal input unit, an input protection circuit and a plurality of optical couplers.
The signal input unit comprises several IN ports and one COM port (common port). The signal input unit is typically a passive signal such as a relay output contact or the like. As shown IN fig. 2, IN normal operation, when the IN ports (IN1 to IN4) and the COM port (common port) of the signal input unit are short-circuited, the input terminal of the photocoupler connected to the corresponding IN port is turned on, the output terminal of the photocoupler is at a low level "0", and when the IN ports (IN1 to IN4) and the COM port (common port) of the signal input unit are turned off, the input terminal of the photocoupler connected to the corresponding IN port is not turned on, and the output terminal of the photocoupler is at a high level "1".
Because the light emitting source of optoelectronic coupler input is mostly emitting diode, its conduction current and reverse breakdown voltage are all less generally, when using, if have the mistake and insert high-voltage signal, cause the burnout of optoelectronic coupler easily.
An input protection circuit: the IN ports (IN 1-IN 4) of the signal input unit are respectively connected with the cathode input end of a photoelectric coupler through a reverse high-voltage resistant diode (D1-D4), so that the aim of preventing a high-voltage signal from being connected into the cathode input of the photoelectric coupler through the IN port to cause reverse high-voltage breakdown of the input end of the photoelectric coupler is fulfilled; a self-recovery fuse is connected in series between the COM port of the signal input unit and the internal common terminal COM1, and when the current flowing through the common terminal is greater than the protection value of the fuse, the common terminal is automatically disconnected through fuse fusing to protect subsequent circuits; the internal common terminal COM1 and the IN port of the signal input unit are connected through a diode (D11-D14) IN a forward direction, respectively. When a high-voltage signal is connected to the common terminal COM, the high-voltage signal passes through the self-recovery fuse and directly returns to the IN port through the bypass diodes (D11-D14), and the generated large short-circuit current directly fuses (high resistance) the self-recovery fuse circuit to protect a subsequent circuit.
When the external abnormal signal is cancelled, the self-recovery safety circuit can automatically recover (low resistance), and the normal work of the circuit is ensured.
Furthermore, the improved circuit also comprises a protection action detection circuit of the self-recovery fuse, which comprises a photoelectric coupler, a reverse diode (D5) and a current-limiting resistor, wherein the COM port of the signal input unit is connected with the cathode input end of the photoelectric coupler through a reverse diode (reverse voltage cut-off); the anode input end of the photoelectric coupler is connected with an internal power supply V through a current-limiting resistorDD(ii) a When the self-recovery fuse does not act, the photoelectric coupler in the protection action detection circuit can be conducted, at this time, the output end of the photoelectric coupler is low level '0', and when the self-recovery fuse acts, the protection action detection circuit is disconnected due to the disconnection of the loopThe output end of the photoelectric coupler is at high level 1 when the photoelectric coupler in the middle can not be conducted.
The controller can judge whether the protection action detection circuit acts or not by detecting the output signal of the photoelectric coupler of the protection action detection circuit and give a relevant prompt to a user.
The following is a detailed description with reference to the examples:
as shown in fig. 2, in the first embodiment: when high voltage is present between any two ports of the IN port, e.g. when VIN1＝220V,VIN2At 0V, the entire circuit cannot be looped due to the reverse voltage cutoff of the diode (D1) connected to the IN1 port, and at this time, the photocouplers connected to the IN1 port and the IN2 port, respectively, are not affected by the high voltage input and are protected from being burned.
As shown in fig. 2, the second embodiment: when the IN port is currently at a high voltage and the COM port is currently at a low voltage, e.g. when VIN1＝220V,VCOMAt 0V, the entire circuit cannot be looped due to the reverse voltage cutoff of the diode (D1) connected to the IN1 port, and the corresponding photocoupler is not burned out by high voltage breakdown.
As shown in fig. 2, example three: when the current COM port is high and one IN port is low, e.g. when VIN1＝0V,VCOMWhen the voltage is 220V, at the moment, a diode (D11) connected with the IN port with low voltage is conducted IN a bypass mode to form a short circuit loop, a self-recovery fuse (L1) is fused, and a large current does not pass through a photoelectric coupler connected with the IN port, so that the photoelectric coupler is guaranteed not to be burnt. The protection action detection circuitry's opto-coupler input is because the high resistance state of self-resuming insurance, by the state switch that originally switches on to can not the on-state, detects the jump of output signal at protection action detection circuitry's optoelectronic coupler output, and the suggestion is current self-resuming fuse takes place the fusing, and the control panel can detect the action of self-resuming insurance according to this state change that detects the opto-coupler.
As shown in fig. 3, the improved second optical coupler input detection circuit with protection function of the present application includes a signal input unit, an input protection circuit and a plurality of optical couplers. Compared to the circuit of fig. 2, there are also the following main differences:
the current flows to: the common terminal IN fig. 2 is connected to GND of the internal power supply through a self-recovery fuse, and during normal operation, the external signal current flows from the IN terminal to the COM terminal; the common terminal of fig. 3 is connected to VDD of the internal power supply through the self-recovery fuse, and during normal operation, the external signal current flows from the COM terminal to the IN terminal.
A bypass circuit: IN FIG. 2, the internal common terminal COM1 and the IN port of the signal input unit are respectively connected through a forward diode (D11-D14) for bypassing the abnormal condition of the COM terminal high voltage; and the internal common terminal COM1 of fig. 3 and the IN port of the signal input unit are respectively connected through a reverse diode (D11-D14) for bypassing the abnormal condition of the high voltage at the IN terminal.
Input signal opto-coupler circuit: IN fig. 2, the IN port of the signal input unit is connected to the reverse protection diode and then to the cathode of the photocoupler; IN fig. 3, the IN port of the signal input unit is connected to the anode of the photoelectric coupler, and the cathode of the photoelectric coupler is connected to the reverse protection diode; however, the polarity directions of the reverse protection diodes in the input signal optocoupler circuits of the above 2 circuits are all consistent with the polarity direction of the input end of the optocoupler. In the specific implementation, the connection position of the reverse protection diode in the input signal optical coupling loop in fig. 2 can also be applied to fig. 3.
As shown in fig. 3, example four: when a high voltage is applied between any two current IN ports, for example, when VIN1 is 220V and VIN2 is 0V, the entire circuit cannot form a loop due to the reverse voltage blocking effect of the diode (D2) connected to the IN2 port, and at this time, the photo-couplers respectively connected to the IN1 port and the IN2 port are not affected by the high voltage input, so that they are protected from being burned out.
As shown in fig. 3, example five: when the IN port is currently at a low voltage and the COM port is currently at a high voltage, e.g. when VIN1＝0V,VCOMAt 220V, the diode (D1) connected to the IN1 port is turned off by the reverse voltage, so that the whole circuit cannot be looped and the corresponding light is not emittedThe electrical coupler is not burned off by high voltage breakdown.
As shown in fig. 3, example six: when the COM port is low and the IN port is high, for example, when VIN1＝220V,VCOMWhen the voltage is equal to 0V, at the moment, a diode (D11) connected with the IN port with high voltage is conducted IN a bypass mode to form a short circuit loop, a self-recovery fuse (L1) IN the self-recovery circuit is fused, and a large current does not pass through a photoelectric coupler connected with the IN port, so that the photoelectric coupler is guaranteed not to be burnt. The protection action detection circuitry's opto-coupler input is because the high resistance state of self-resuming insurance, by the state switch that originally switches on to can not the on-state, detects the jump of output signal at protection action detection circuitry's optoelectronic coupler output, and the suggestion is current self-resuming fuse takes place the fusing, and the control panel can detect the action of self-resuming insurance according to this state change that detects the opto-coupler.
In a specific application, the user can select a signal input unit with more ports according to practical situations, and the signal input unit is not limited to the type mentioned in the application.
And the diode and the self-recovery fuse of the optocoupler input protection circuit are both high-voltage resistant.
The circuit design can be applied to direct-current voltage or alternating-current voltage input protection.
The type of access circuit may be determined according to the actual situation and is not particularly limited.
The foregoing description shows and describes several preferred embodiments of the invention, but as aforementioned, it is to be understood that the invention is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The utility model provides an optical coupling input protection circuit, includes signal input unit, input protection circuit and optoelectronic coupler, and signal input unit is connected its characterized in that with input protection circuit, optoelectronic coupler in proper order:
the signal input unit is a passive signal input;
the IN ports of the signal input units are respectively connected with photoelectric couplers, and diodes are arranged IN a photoelectric coupling input loop to cut off reverse high voltage;
a self-recovery fuse is connected in series between the COM port of the signal input unit and the internal circuit;
the IN ports of the signal input units are connected to the internal common terminal COM1 through diodes, respectively.
2. The optocoupler input protection circuit of claim 1, further comprising a protection action detection circuit comprising a photocoupler, a reverse diode, and a current limiting resistor.
3. An optocoupler input protection circuit according to any of claims 1-2, characterized in that the signal input unit comprises a number of signal input ports and an input common port.
4. The optocoupler input protection circuit of claim 1, wherein the IN port of the signal input unit and the diode IN the optocoupler input loop have polarity directions that always coincide with the input terminal polarity direction of the optocoupler, respectively.
5. An optocoupler input protection circuit according to claim 1, characterized IN that the IN ports of the signal input units are connected to the internal common COM1 via a forward diode respectively.
6. An optocoupler input protection circuit according to claim 1, characterized IN that the IN ports of the signal input units are connected to the internal common COM1 through an inverted diode respectively.
7. A control method using the optocoupler input protection circuit according to claim 1, characterized in that:
when high voltage exists between any two ports of an IN port of the signal input unit, the whole circuit loop is not conducted at the moment because a diode for carrying out reverse protection for cutting off the high voltage is arranged IN the loop, and a corresponding photoelectric coupler does not have large current to pass through, so that the photoelectric coupler is ensured not to be burnt;
when there is a high voltage between the COM port of the signal input unit and the IN port of the signal input unit: a diode for cutting off and reversely protecting the high voltage is arranged in the loop, at the moment, the whole circuit loop is not conducted, and the corresponding photoelectric coupler has no large current, so that the photoelectric coupler is ensured not to be burnt; or the voltage is conducted through the diode bypass to form a short circuit loop, the self-recovery fuse is broken, and the photoelectric coupler connected with the IN port has no large current to pass through, so that the photoelectric coupler is guaranteed not to be burnt.
8. The control method of the optocoupler input protection circuit according to claim 7, characterized in that: once the self-recovery fuse is fused, the connection from the COM port of the protection action detection circuit to the internal common end COM1 is disconnected, the photoelectric coupler of the protection action detection circuit is not conducted, and the output end of the photoelectric coupler of the protection action detection circuit detects the jump of an output signal to prompt that the self-recovery fuse is fused at present.
9. The control method of the optocoupler input protection circuit according to claim 7, characterized in that: when the voltage applied at the input end disappears for a period of time, the self-recovery fuse can automatically recover the low-resistance state.
10. The control method of the optocoupler input protection circuit according to claim 7, characterized in that: and the diode and the self-recovery fuse of the optocoupler input protection circuit are both high-voltage resistant.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710013160.3A CN108288846B (en) | 2017-01-09 | 2017-01-09 | Optical coupler input protection circuit and protection method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710013160.3A CN108288846B (en) | 2017-01-09 | 2017-01-09 | Optical coupler input protection circuit and protection method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108288846A CN108288846A (en) | 2018-07-17 |
| CN108288846B true CN108288846B (en) | 2020-07-03 |
Family
ID=62819276
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710013160.3A Active CN108288846B (en) | 2017-01-09 | 2017-01-09 | Optical coupler input protection circuit and protection method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108288846B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109302773A (en) * | 2018-11-15 | 2019-02-01 | 常州格林照明股份有限公司 | A kind of LED projector lamp driving circuit |
| CN111007434A (en) * | 2019-12-25 | 2020-04-14 | 深圳万讯自控股份有限公司 | Output short circuit detection protection circuit and method |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101272047A (en) * | 2008-05-15 | 2008-09-24 | 佛山市中格威电子有限公司 | Five-in-one intelligent digital general air conditioner protector |
| CN102184750A (en) * | 2011-04-11 | 2011-09-14 | 北京广利核系统工程有限公司 | Testing device of nuclear power station digitized instrument and control system |
| CN202503258U (en) * | 2012-04-07 | 2012-10-24 | 乐清市恒亚电气有限公司 | Wide-voltage phase sequence, in-phase and loss-of-phase protector |
| CN204789923U (en) * | 2015-05-26 | 2015-11-18 | 吴小燕 | Failure detector circuit |
| US9351366B1 (en) * | 2014-11-27 | 2016-05-24 | Yujing Technology Co., Ltd. | Isolation dimmer circuit structure |
| CN206370677U (en) * | 2017-01-09 | 2017-08-01 | 展鹏科技股份有限公司 | A kind of optocoupler input protection circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103297033B (en) * | 2013-06-14 | 2016-06-08 | 南京电力自动化设备三厂有限公司 | A kind of pulse signal acquisition circuit |
-
2017
- 2017-01-09 CN CN201710013160.3A patent/CN108288846B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101272047A (en) * | 2008-05-15 | 2008-09-24 | 佛山市中格威电子有限公司 | Five-in-one intelligent digital general air conditioner protector |
| CN102184750A (en) * | 2011-04-11 | 2011-09-14 | 北京广利核系统工程有限公司 | Testing device of nuclear power station digitized instrument and control system |
| CN202503258U (en) * | 2012-04-07 | 2012-10-24 | 乐清市恒亚电气有限公司 | Wide-voltage phase sequence, in-phase and loss-of-phase protector |
| US9351366B1 (en) * | 2014-11-27 | 2016-05-24 | Yujing Technology Co., Ltd. | Isolation dimmer circuit structure |
| CN204789923U (en) * | 2015-05-26 | 2015-11-18 | 吴小燕 | Failure detector circuit |
| CN206370677U (en) * | 2017-01-09 | 2017-08-01 | 展鹏科技股份有限公司 | A kind of optocoupler input protection circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108288846A (en) | 2018-07-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7944653B2 (en) | Self fault-detection circuit for ground fault circuit interrupter | |
| CN103069530B (en) | The DC load cut-off catalyst of quasiconductor auxiliary | |
| KR101247208B1 (en) | Earth leakage breaker | |
| US10004123B1 (en) | Failure detection and alerting circuit for a differential mode surge protection device in an LED driver | |
| MXPA06008708A (en) | Ground fault circuit interrupter (gfci) end-of-life (eol) status indicator. | |
| EP2526620B1 (en) | Optocoupler circuit for gate driver | |
| JP7097459B2 (en) | Circuit breaker control module | |
| GB2518733A (en) | Neutral line breakage detection circuit, method and corresponding residual current circuit breaker | |
| CN108288846B (en) | Optical coupler input protection circuit and protection method thereof | |
| KR20180066203A (en) | AC load detection circuit | |
| WO2011006411A1 (en) | Dc fan fault detecting device and method with alarm | |
| CN103631163B (en) | A kind of on-off circuit of AC power | |
| CN206370677U (en) | A kind of optocoupler input protection circuit | |
| EP3471229A1 (en) | Switching apparatus for residual current circuit breaker | |
| CN110581531B (en) | Open-circuit preventing device of current transformer | |
| KR20210027325A (en) | Electronic protective circuit | |
| KR101186896B1 (en) | Short circuit protection apparatus using diode | |
| RU2246161C1 (en) | Device for protection of electrical installations against abnormal operating conditions | |
| CN111722101A (en) | Detection circuit and protection method of double-loop relay | |
| CN114552528B (en) | Train LCU protection circuit and fault detection method thereof | |
| CN206250744U (en) | A kind of resistance to shorting electronic switch | |
| CN218592025U (en) | Open-phase protection control circuit of three-phase inverter welding machine | |
| CN106786464B (en) | Active protection type sensor isolation protection circuit | |
| CN216560832U (en) | Grounding detection circuit and electric appliance | |
| CN212905371U (en) | Short circuit detection circuit of safety loop to ground wire |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |