CN106546804A - A kind of transistor over-current detection circuit - Google Patents
A kind of transistor over-current detection circuit Download PDFInfo
- Publication number
- CN106546804A CN106546804A CN201611226091.6A CN201611226091A CN106546804A CN 106546804 A CN106546804 A CN 106546804A CN 201611226091 A CN201611226091 A CN 201611226091A CN 106546804 A CN106546804 A CN 106546804A
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- Prior art keywords
- transistor
- current detection
- detection circuit
- supply line
- transistor over
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/36—Overload-protection arrangements or circuits for electric measuring instruments
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
- G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
- G01R19/16547—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies voltage or current in AC supplies
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses a kind of transistor over-current detection circuit, being related to over-current detection technical field includes the elements such as single phase poaer supply line (L, N), chopper (QF), fuse (FU), catalyst (KM), auxiliary reclay (KA), current transformer (TA), step-down transformer (T), rectifier bridge (UR1), rectifier bridge (UR2), transistor (VT1), transistor (VT2), three terminal regulator 7812, resistance, electric capacity, light emitting diode.Transistor over-current detection circuit simple structure of the present invention, cost are relatively low；Circuit can automatically cut off power supply when user power utilization overcurrent or supply line are short-circuited failure.
Description
Technical field
The present invention relates to over-current detection technical field, more particularly to a kind of transistor over-current detection circuit.
Background technology
Overcurrent protection is exactly, when electric current exceedes predetermined maximum, to make a kind of protected mode of protection device action, when
When flowing through the electric current protected in original paper more than certain numerical value adjusted in advance, protection device starts, and uses time limit safety action
Selectivity, make circuit breaker trip or provide alarm signal.When there is phase fault in electrical network, electric current can increase suddenly,
Voltage declines suddenly, and overcurrent protection is exactly the requirement by route choosing, the action current of setting current relay, works as circuit
When middle fault current reaches the working value of electric current relay, electric current relay action has choosing by protection device selectively requirement
The disengagement failure circuit of selecting property.
The content of the invention
The present invention is electric in order to power supply is automatically cut off when user power utilization overcurrent or supply line are short-circuited failure
A kind of road, there is provided transistor over-current detection circuit.
For achieving the above object, the technical solution used in the present invention is：
A kind of transistor over-current detection circuit, including single phase poaer supply line (L, N), the single phase poaer supply line (L, N) lead to successively
It is load supplying to cross chopper (QF), fuse (FU), the main contacts of catalyst (KM), the coil of catalyst (KM) with it is middle after
It is connected in parallel between single phase poaer supply line (L, N) after the normally-closed contact series connection of electrical equipment (KA)；Single phase poaer supply line (L, N) two ends are connected with change
Depressor (T) former limit, transformator (T) secondary are filtered by filter capacitor (C2), with three-terminal voltage-stabilizing through rectifier bridge (UR2) rectification
The input of device 7812 is connected, and the earth terminal of three terminal regulator 7812 is connected to the ground, the outfan output of three terminal regulator 7812
12V unidirectional currents；Current transformer (TA) former limit is serially connected on single phase poaer supply line (L), and current transformer (TA) secondary is through rectification
Bridge (UR1) rectification, is filtered by filter capacitor (C1), and resistance (R1) is connected in parallel on filter capacitor (C1) two ends, transistor (VT1)
Base stage is connected with resistance (R1), and the emitter stage of transistor (VT1) is connected with the base stage of transistor (VT2), the collection of transistor (VT1)
Electrode is connected with the colelctor electrode of transistor (VT2), coil one end and transistor (VT2) current collection of auxiliary reclay (KA)
Extremely it is connected, the other end is electrically connected with 12V direct currents.
Further, the transformator (T) is step-down transformer.
Further, the turn ratio of transformator (T) primary and secondary side is 18:1.
Further, resistance (R2) after connecting with light emitting diode (VD1), is connected in parallel on the coil of auxiliary reclay (KA)
Two ends.
Further, the normally opened contact of auxiliary reclay (KA) is connected in parallel on transistor (VT2) after connecting with button (SB)
Colelctor electrode and emitter stage between.
Further, resistance (R3) is connected in parallel on 7812 outfan of three terminal regulator after connecting with light emitting diode (VD3)
Between ground.
Further, diode (VD2) is connected between the outfan and input of the three terminal regulator 7812.
Further, the outfan of the three terminal regulator 7812 is parallel with output filter capacitor (C3).
Beneficial effects of the present invention：A kind of transistor over-current detection circuit, over-current detection circuit by transistor, catalyst,
The elements such as auxiliary reclay, current transformer, step-down transformer, manostat, rectifier bridge, filter capacitor are constituted, circuit structure letter
Single, cost is relatively low；The circuit can automatically cut off power supply electricity when user power utilization overcurrent or supply line are short-circuited failure
Source.
Description of the drawings
Fig. 1 is over-current detection circuit schematic diagram of the present invention.
Specific embodiment
In order that technological means, creation characteristic, reached purpose and effect that the present invention is realized are easy to understand, tie below
Conjunction is specifically illustrating, and the present invention is expanded on further.
When being embodied as, with reference to Fig. 1, a kind of transistor over-current detection circuit, including single phase poaer supply line (L, N), chopper
(QF), fuse (FU), catalyst (KM), auxiliary reclay (KA), current transformer (TA), step-down transformer (T), rectifier bridge
(UR1), rectifier bridge (UR2), transistor (VT1), transistor (VT2), three terminal regulator 7812.Single phase poaer supply line (L, N) is successively
It is load supplying by the main contacts of chopper (QF), fuse (FU), catalyst (KM).The coil of catalyst (KM) and centre
It is connected in parallel between single phase poaer supply line (L, N) after the normally-closed contact series connection of relay (KA).Single phase poaer supply line (L, N) two ends are connected with
Transformator (T) former limit, transformator (T) secondary are filtered by filter capacitor (C2) through rectifier bridge (UR2) rectification, steady with three ends
The input of depressor 7812 is connected, and the earth terminal of three terminal regulator 7812 is connected to the ground, and the outfan of three terminal regulator 7812 is defeated
Go out 12V unidirectional currents.Transformator (T) is step-down transformer, and the turn ratio of step-down transformer primary and secondary side is 18:1.Current Mutual Inductance
Device (TA) former limit is serially connected on single phase poaer supply line (L), current transformer (TA) secondary through rectifier bridge (UR1) rectification, by filter
Ripple electric capacity (C1) is filtered, and resistance (R1) is connected in parallel on filter capacitor (C1) two ends, base stage and resistance (R1) phase of transistor (VT1)
Even, the emitter stage of transistor (VT1) is connected with the base stage of transistor (VT2), the colelctor electrode and transistor of transistor (VT1)
(VT2) colelctor electrode is connected, and coil one end of auxiliary reclay (KA) is connected with transistor (VT2) colelctor electrode, another
End is electrically connected with 12V direct currents.There is resistance (R2) after connecting with light emitting diode (VD1), to be connected in parallel on the coil of auxiliary reclay (KA)
Two ends.The normally opened contact for having auxiliary reclay (KA) is connected in parallel on the colelctor electrode of transistor (VT2) and is sent out after being connected with button (SB)
Between emitter-base bandgap grading.There is resistance (R3) to be connected in parallel between 7812 outfan of three terminal regulator and ground after connecting with light emitting diode (VD3).
Diode (VD2) is connected between the outfan and input of three terminal regulator 7812.The outfan of three terminal regulator 7812 is simultaneously
It is associated with output filter capacitor (C3).
During specific works, chopper (QF) is connected, catalyst (KM) coil in main circuit obtains electric, catalyst (KM) is main to be touched
Point closure, single phase alternating current power supply is load supplying.If customer power supply power consumption is without departing from electric current predetermined value, step-down transformer
(T) 220V alternating currents are become into 12V alternating currents, by rectifier bridge (UR2) rectification, after filter capacitor (C2) filtering, then through three ends
Manostat 7812 is stable into 12V unidirectional currents, and on the one hand 12V unidirectional currents are resistance (R3), light emitting diode (VD2) is powered, and are lighted
Diode (VD2) is luminous to show user's normal electricity consumption；On the other hand 12V unidirectional currents are given auxiliary reclay (KA), resistance (R2), are sent out
Optical diode (VD1) is powered.When user's normal electricity consumption, resistance (R1) is partial pressure potential device, and the electric resistance partial pressure of lower end is relatively low, makes
Obtain transistor (VT1), transistor (VT2) to be not turned on, auxiliary reclay (KA) coil losing electricity, light emitting diode (VD1) do not light.
When user connects the larger electrical equipment of power or circuit short trouble occurs, the electric current increase in main circuit is a lot,
The current surge that current transformer (TA) former limit in measure loop flows through, the electric current of current transformer (TA) secondary sensing
Increase, after rectifier bridge (UR2) rectification, filter capacitor (C1) filtering, transistor is worked as in electric resistance partial pressure increase in resistance (R1) lower end
(VT1), when base voltage is more than 1.4V, transistor (VT1), transistor (VT2) conducting, auxiliary reclay (KA) coil obtain electric,
Auxiliary reclay (KA) normally-closed contact disconnects so that catalyst (KM) coil losing electricity, and catalyst (KM) main contacts disconnects, and cut-out is single
Phase power supply powers to the load.Meanwhile, auxiliary reclay (KA) normally opened contact closure, 12V unidirectional currents are continuously auxiliary reclay
(KA) coil power supply, light emitting diode (VD1) is luminous to remind the super power consumption of user or line fault.Only when reduce power consumption or
Press the button (SB), auxiliary reclay (KA) coil blackout, auxiliary reclay (KA) normally-closed contact resets, catalyst (KM) coil
Just can again it is electric so as to main contacts close, connect single phase poaer supply, be that user load is powered.
Transistor over-current detection circuit of the present invention, over-current detection circuit is by transistor, catalyst, auxiliary reclay, electric current
The elements such as transformer, step-down transformer, manostat, rectifier bridge, filter capacitor are constituted, and circuit structure is simple, cost is relatively low；The electricity
Road can automatically cut off power supply when user power utilization overcurrent or supply line are short-circuited failure.
Claims (8)
1. a kind of transistor over-current detection circuit, including single phase poaer supply line (L, N), the single phase poaer supply line (L, N) are passed sequentially through
Chopper (QF), fuse (FU), the main contacts of catalyst (KM) are load supplying, it is characterised in that：The line of catalyst (KM)
Circle is connected in parallel between single phase poaer supply line (L, N) after being connected with the normally-closed contact of auxiliary reclay (KA)；Single phase poaer supply line (L, N) two
End is connected with transformator (T) former limit, and transformator (T) secondary is filtered by filter capacitor (C2) through rectifier bridge (UR2) rectification,
It is connected with the input of three terminal regulator 7812, the earth terminal of three terminal regulator 7812 is connected to the ground, three terminal regulator 7812
Outfan exports 12V unidirectional currents；Current transformer (TA) former limit is serially connected on single phase poaer supply line (L), and current transformer (TA) is secondary
While through rectifier bridge (UR1) rectification, being filtered by filter capacitor (C1), resistance (R1) is connected in parallel on filter capacitor (C1) two ends, brilliant
The base stage of body pipe (VT1) is connected with resistance (R1), and the emitter stage of transistor (VT1) is connected with the base stage of transistor (VT2), crystal
The colelctor electrode of pipe (VT1) is connected with the colelctor electrode of transistor (VT2), coil one end of auxiliary reclay (KA) and transistor crystal
Pipe (VT2) colelctor electrode is connected, and the other end is electrically connected with 12V direct currents.
2. according to a kind of transistor over-current detection circuit described in claim 1, it is characterised in that：The transformator (T) is drop
Pressure transformer.
3. according to a kind of transistor over-current detection circuit described in claim 2, it is characterised in that：Transformator (T) former limit
Turn ratio with secondary is 18:1.
4. according to a kind of transistor over-current detection circuit described in claim 1, it is characterised in that：There is resistance (R2) with luminous two
The coil two ends of auxiliary reclay (KA) are connected in parallel on after pole pipe (VD1) series connection.
5. according to a kind of transistor over-current detection circuit described in claim 1, it is characterised in that：There is auxiliary reclay (KA)
Normally opened contact is connected in parallel on after being connected with button (SB) between the colelctor electrode and emitter stage of transistor (VT2).
6. according to a kind of transistor over-current detection circuit described in claim 1, it is characterised in that：There is resistance (R3) with luminous two
It is connected in parallel between 7812 outfan of three terminal regulator and ground after pole pipe (VD3) series connection.
7. according to a kind of transistor over-current detection circuit described in claim 1, it is characterised in that：The three terminal regulator 7812
Outfan and input between be connected with diode (VD2).
8. according to a kind of transistor over-current detection circuit described in claim 1, it is characterised in that：The three terminal regulator 7812
Outfan be parallel with output filter capacitor (C3).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611226091.6A CN106546804A (en) | 2016-12-27 | 2016-12-27 | A kind of transistor over-current detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611226091.6A CN106546804A (en) | 2016-12-27 | 2016-12-27 | A kind of transistor over-current detection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN106546804A true CN106546804A (en) | 2017-03-29 |
Family
ID=58397799
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201611226091.6A Withdrawn CN106546804A (en) | 2016-12-27 | 2016-12-27 | A kind of transistor over-current detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN106546804A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108318730A (en) * | 2018-03-30 | 2018-07-24 | 成都众宜天成科技有限公司 | A kind of communication power supply voltage detecting circuit |
-
2016
- 2016-12-27 CN CN201611226091.6A patent/CN106546804A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108318730A (en) * | 2018-03-30 | 2018-07-24 | 成都众宜天成科技有限公司 | A kind of communication power supply voltage detecting circuit |
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Application publication date: 20170329 |
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| WW01 | Invention patent application withdrawn after publication |