CN201780345U - Switching element poor closing detecting circuit - Google Patents
Switching element poor closing detecting circuit Download PDFInfo
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- CN201780345U CN201780345U CN2009202845789U CN200920284578U CN201780345U CN 201780345 U CN201780345 U CN 201780345U CN 2009202845789 U CN2009202845789 U CN 2009202845789U CN 200920284578 U CN200920284578 U CN 200920284578U CN 201780345 U CN201780345 U CN 201780345U
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Abstract
The utility model provides a circuit used for detecting whether a closing state of a switching element (an electronic element or a mechanical element) is fine or not, and belongs to the technical field of electrical and electronic application. The detecting circuit connected in parallel to two ends of the switching element comprises a current limiting circuit unit, an over-current protection circuit unit and a triggering circuit unit. When voltage of two ends of the switching element exceeds a certain value due to poor-contact closing of the switching element in work, signal level outputted by the detecting circuit is reversed to give alarm to a main circuit controller so that the main circuit controller cuts off a power supply and heating damage to a switch and peripheral equipment and fire accident of the integral circuit are prevented. The detecting circuit has the advantages of simple structure, small number of used elements, low cost and capability of effectively improving operation reliability of a switch circuit.
Description
Technical field
The utility model relates to the closed bad testing circuit of a kind of switching device, belongs to the electric and electronic applied technical field.
Background technology
Having in the power electronic system of AC-DC change-over circuit as frequency converter, induction heating, uninterrupted power source etc., for level and smooth commutating voltage waveform, minimizing DC voltage ripple, DC side generally need connect the electrochemical capacitor of larger capacity.Electrochemical capacitor both end voltage before power supply drops into is almost nil, and switch combined floodgate moment will produce very big surge impact electric current like this.This surge current causes the damage of rectifier bridge, electrochemical capacitor etc. easily.For this reason, generally suppress resistance, as shown in Figure 1 at a switch ends surge current in parallel.Throwing electric moment, switch SW disconnects, and electric current suppresses resistance R in through surge current and charges for electrochemical capacitor and load circuit.Because the existence of resistance, surge current is reduced greatly.After treating that capacitance voltage rises to certain value, close a switch, system enters the normal power supply state.
Yet because factor affecting such as the environment of the quality problems of switching device own or field of employment is abominable, switch is after closing, and its upper and lower contact may produce closed bad phenomenon, causes contact resistance to increase.When big electric current flows through, the power consumption on the switching device will sharply increase, and cause that switch contact burns out, and when serious, the on-off element fever time is long, and the objects such as device itself and peripheral circuits, electric wire that can ignite cause fire failure.
In order to prevent the generation of this class accident, some system selects the on-off element from contact-carrying adhesive measuring ability for use, and some system selects the international famous brand switch that has good quality for use.These schemes can improve the security of on-off circuit really, but can increase the cost of system greatly.
Summary of the invention
The utility model aims to provide a kind of simple and practical switching device closed condition testing circuit, and is bad or send alerting signal when losing efficacy in switching device work.Circuit constitutes simple, with low cost, can effectively improve the reliability of on-off circuit.
The utility model circuit is connected in parallel on switching device SW two ends, comprises current-limiting circuit, circuit overcurrent protection and three circuit units of trigger circuit.
Above-mentioned current-limiting circuit unit is made up of resistance R 1, and the one end links to each other with a contact of switching device SW, and the other end is connected with resistance R 2 in the described circuit overcurrent protection.
Above-mentioned circuit overcurrent protection unit comprises the base drive circuit G1 of resistance R 2, triode Q1 and Q1.One end of described resistance R 2 connects the Q1 base drive circuit and is connected to resistance R 1, and the other end connects the collector of Q1.The negative pole of the emitter of triode Q1 and Q1 base drive circuit is connected to the b contact of switch SW.
Above-mentioned trigger circuit unit comprises base drive circuit G2, photoelectrical coupler PC, direct supply VCC-GND and the resistance R 3 of triode Q2, Q2.The emission side positive pole of described photoelectrical coupler PC links to each other with the collector of above-mentioned circuit overcurrent protection unit triode Q1, and the emission side negative pole of PC links to each other with the collector of described triode Q2, and the emitter of triode Q2 connects the emitter of triode Q1.The sensitive side positive pole of photoelectrical coupler PC is connected to the anodal VCC of direct supply VCC-GND by resistance R 3 and as signal output part of the present utility model, the negative pole of PC sensitive side is received the negative pole GND of power supply VCC-GND.Q2 base drive circuit G2 one end is connected the emission side positive pole of photoelectrical coupler PC, and the other end is connected to the emitter of triode Q2.
The another kind of circuit form of above-mentioned trigger element is that circuit only is made up of base drive circuit G2, resistance R 3 and the direct supply VCC-GND of triode Q2, Q2.The collector of described triode Q2 is connected to the anodal VCC of direct supply VCC-GND by resistance R 3, and as signal output part of the present utility model, the emitter of Q2 links to each other with the negative pole GND of direct supply VCC-GND, and is connected to the b contact of switching device SW jointly.Q2 base drive circuit G2 one end is connected the collector of triode Q2, and the other end is connected to the emitter of Q2.
Principle of work of the present utility model is: when producing closed bad phenomenon in the switching device SW work, its both end voltage produces electric current in the loop that the base drive circuit G2 by resistance R 1, resistance R 2, triode Q2 forms, when this electric current reaches certain value, G2 drives triode Q2 conducting, photoelectrical coupler PC emission side has electric current to flow through and is luminous, the PC sensitive side receives its inner triode conducting behind this photosignal, the anodal level of sensitive side is by high step-down, that is output signal of the present utility model becomes low level by high level.By checking the variation of this signal level, can judge whether switching device exists closed bad phenomenon.Do not have the circuit form of photoelectrical coupler for trigger element, its collector level is low by hypermutation after the triode Q2 conducting, causes the utility model output signal level to change equally.Resistance R 1 is used to limit the electric current that flows through on the trigger circuit components and parts.Resistance R 2 is used to detect the electric current that flows through trigger element; when this electric current reaches the overcurrent protection threshold value; the base drive circuit work of triode Q1; drive triode Q1 conducting; big electric current is got back in the switch SW side main circuit by resistance R 1 and triode Q1 gone, thereby the protection trigger circuit are avoided heavy current impact.
Description of drawings
Fig. 1: power supply has the AC rectification system of surge current inhibit feature when dropping into.
Fig. 2: a kind of photoelectrical coupler (that is so-called insulated type) switch-closed condition testing circuit legend that has that the utility model relates to.
Fig. 3: a kind of photoelectrical coupler (that is so-called nonisulated type) switch-closed condition testing circuit legend of not being with that the utility model relates to.
Embodiment
As shown in Figure 2, the closed bad testing circuit of a kind of switching device comprises current-limiting circuit unit, circuit overcurrent protection unit and trigger circuit unit.The current-limiting circuit unit comprises resistance R 1 (10k Ω); The circuit overcurrent protection unit comprises resistance R 2 (20 Ω), triode Q1 (2SC2712) and Q1 base drive circuit G2; Trigger element comprises photoelectrical coupler PC (TLP181GR), triode Q2 (2SC6026) and Q2 base drive circuit G2, resistance R 3 (2.2k Ω), direct supply VCC (5V).It is in parallel that the utility model circuit and on-off element SW (PCD124D1M) and surge current are suppressed resistance R in (75 Ω), and the output terminal of testing circuit is connected to equally by control chips such as the DSP of direct supply VCC power supply or MCU.When control chip detects the incoming signal level counter-rotating after switch closes, show that promptly testing circuit has detected the bad fault of switch closure.In order to prevent trigger circuit, between testing circuit output terminal and direct supply GND or at holding circuit resistance R 2 two ends, may need but be not respectively to increase a ceramic filter capacitor (1nF) because of the mistake protection action that circuit noise produces wrong alerting signal or current foldback circuit.
The load that this circuit is suitable for the switching device supply is capacitive load or active property controllable load, and promptly switch off state does not have high voltage to continue to be present in the switching device two ends.Described switching device can be the various switching devices that are used for connecting and disconnecting of the circuit control such as relay, contactor, isolating switch.
Claims (4)
1. the closed bad testing circuit of switching device is characterized in that described circuit is connected in parallel on switching device SW two ends, is made up of three circuit units such as current-limiting circuit, circuit overcurrent protection and trigger circuit.
2. according to the closed bad testing circuit of the switching device described in the claim 1, it is characterized in that current-limiting circuit comprises a resistance R 1, R1 one end connects a contact of switching device SW, and the other end connects the resistance R 2 in the described circuit overcurrent protection.
3. according to the closed bad testing circuit of the switching device described in the claim 1; it is characterized in that circuit overcurrent protection comprises the base drive circuit G1 of resistance R 2 and triode Q1 and Q1; one end of resistance R 2 connects above-mentioned resistance R 1 and Q1 base drive circuit G1; the other end connects the collector of Q1, and the negative pole of the emitter of Q1 and Q1 base drive circuit is connected to the b contact of switching device SW.
4. according to the closed bad testing circuit of the switching device described in the claim 1, it is characterized in that the trigger circuit output terminal has insulation and nonisulated two kinds of circuit forms, the insulated type testing circuit comprises photoelectrical coupler PC, triode Q2, the base drive circuit G2 of Q2, compositions such as resistance R 3 and direct supply VCC-GND, the anodal end that connects above-mentioned resistance R 2 of the emission side of photoelectrical coupler PC, negative pole is connected to the collector of triode Q2, the emitter of triode Q2 connects the emitter of triode Q1 and is connected to the b contact of switching device SW jointly, the sensitive side positive pole of photoelectrical coupler PC is connected to the anodal VCC of direct supply VCC-GND by resistance R 3, as signal output part of the present utility model, the sensitive side negative pole is connected to the negative pole GND of direct supply VCC-GND; Nonisulated type testing circuit comprises the compositions such as base drive circuit, resistance R 3 and direct supply VCC-GND of triode Q2, Q2, the collector of triode Q2 is connected to the anodal VCC of direct supply VCC-GND by resistance R 3, as signal output part of the present utility model, the emitter of triode Q2 connects the negative pole GND of direct supply VCC-GND and is connected to the b contact of switching device SW jointly.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202845789U CN201780345U (en) | 2009-12-12 | 2009-12-12 | Switching element poor closing detecting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202845789U CN201780345U (en) | 2009-12-12 | 2009-12-12 | Switching element poor closing detecting circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201780345U true CN201780345U (en) | 2011-03-30 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2009202845789U Expired - Lifetime CN201780345U (en) | 2009-12-12 | 2009-12-12 | Switching element poor closing detecting circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201780345U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104360213A (en) * | 2014-10-31 | 2015-02-18 | 深圳怡化电脑股份有限公司 | Detection circuit |
| CN106771807A (en) * | 2016-12-19 | 2017-05-31 | 杭州先途电子有限公司 | The detection method of heater switch fault |
-
2009
- 2009-12-12 CN CN2009202845789U patent/CN201780345U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104360213A (en) * | 2014-10-31 | 2015-02-18 | 深圳怡化电脑股份有限公司 | Detection circuit |
| CN106771807A (en) * | 2016-12-19 | 2017-05-31 | 杭州先途电子有限公司 | The detection method of heater switch fault |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| PE01 | Entry into force of the registration of the contract for pledge of patent right |
Denomination of utility model: Switching element poor closing detecting circuit Effective date of registration: 20131209 Granted publication date: 20110330 Pledgee: Agricultural Bank of China Limited by Share Ltd Wuxi science and Technology Branch Pledgor: Jiangsu Reya Electric Co., Ltd. Registration number: 2013990000946 |
|
| PLDC | Enforcement, change and cancellation of contracts on pledge of patent right or utility model | ||
| PC01 | Cancellation of the registration of the contract for pledge of patent right |
Date of cancellation: 20141203 Granted publication date: 20110330 Pledgee: Agricultural Bank of China Limited by Share Ltd Wuxi science and Technology Branch Pledgor: Jiangsu Reya Electric Co., Ltd. Registration number: 2013990000946 |
|
| PLDC | Enforcement, change and cancellation of contracts on pledge of patent right or utility model | ||
| CX01 | Expiry of patent term |
Granted publication date: 20110330 |
|
| CX01 | Expiry of patent term |