CN202550694U

CN202550694U - CT (current transformer) power taking circuit allowing for reducing heat of CT

Info

Publication number: CN202550694U
Application number: CN2012201762992U
Authority: CN
Inventors: 梁忠伟
Original assignee: XIAMEN LEELEN HIGH VOLTAGE ELECTRIC CO Ltd
Current assignee: XIAMEN LEELEN HIGH VOLTAGE ELECTRIC CO Ltd
Priority date: 2012-04-24
Filing date: 2012-04-24
Publication date: 2012-11-21
Anticipated expiration: 2022-04-24

Abstract

The utility model discloses a CT (current transformer) power taking circuit allowing for reducing heat of a CT. The CT power taking circuit comprises a surge suppression loop connected with the CT, a bridge rectifier circuit, an over-voltage shutdown circuit, a GS protection circuit and an electronic switch. The bridge rectifier circuit is disposed at the rear end of the surge suppression loop to rectify. The over-voltage shutdown circuit is disposed between two output ends of the bridge rectifier circuit and is shut down when output voltage of the bridge rectifier circuit is over over-voltage threshold. The GS protection circuit is disposed between an input end and a control end of the electronic switch to be used for protecting the electronic switch. Compared with the prior art, the CT power taking circuit adds the over-voltage shutdown circuit, the electronic switch is switched off when voltage is over the over-voltage threshold, namely a load loop and the CT power taking circuit are disconnected, a large equivalent resistor in the over-voltage shutdown circuit is used for radiating, actual current is only 1-2mA, heat quantity can be ignored, and accordingly long-term stable operation of a whole power supply system can be guaranteed.

Description

A kind of CT power-supply circuit that reduces the CT heating

Technical field

The utility model relates to current transformer power-supply circuit field, relates to a kind of CT power-supply circuit of the CT of reduction heating in particular.

Background technology

CT promptly refers to current transformer, and it is to form according to electromagnetic induction principle; Specifically form by the iron core and the winding of closure; A umber of turn of current transformer seldom, its string is in the circuit of the electric current that needs are measured, so it often has whole electric currents of circuit to flow through; The secondary winding number of turn is then many; It is serially connected in measuring instrument and protects in the loop, and current transformer is when work, and its secondary circuit is closed all the time; Therefore measuring instrument is very little with the impedance of protection loop series coil, and the operating state of current transformer is near short circuit; In brief, current transformer is to be used for big electric current is become behind the little electric current and to be convenient for measuring and to protect.

As shown in Figure 1; It is the common circuit structure of CT power taking; CT output is carried out rectifying and wave-filtering through current rectifying and wave filtering circuit 23 again after surge suppresses loop 21 and overload bleed-off circuit 22, and obtains the galvanic current source through DC-DC or linear voltage-stabilizing circuit 24 and supply load circuit 25.I increases to a certain degree when primary side 50HZ alternating current; The energy of CT output will be greater than the energy of need of load; At this moment the bleed-off circuit 22 that transships will play effect; The approximate short circuit of CT is handled, and current rectifying and wave filtering circuit 23 is inoperative like this, can avoid Vin voltage further to raise and causes the hidden danger of lowering and stabilizing blood pressure chip damage.

When primary current I continue to increase, CT exports abundant energy soon and causes transshipping bleed-off circuit 22 and work after primary current I zero passage, in two zero crossings the remaining time; CT will be near short circuit, and the internal resistance of supposing CT is Rc, and the output average current is Ic; Under the situation of CT short circuit, Ic is maximum so, and heating is the most severe; CT is in short-circuit condition for a long time, will make overload bleed-off circuit 22 serious with the CT self-heating, thereby influences the long-term working stability of whole electric power system.

In view of this, the inventor deeply studies to above-mentioned deficiency of the prior art, has this case to produce then.

The utility model content

The purpose of the utility model is to provide a kind of CT power-supply circuit of the CT of reduction heating, seriously influences the problem of whole electric power system long-term working stability to solve prior art overload bleed-off circuit and CT self-heating.

In order to reach above-mentioned purpose, the solution of the utility model is:

A kind of CT power-supply circuit that reduces the CT heating; Comprise that the surge that confession links to each other with CT suppresses the loop; Wherein, Also comprise bridge rectifier, overvoltage breaking circuit, GS protective circuit and electronic switch; This bridge rectifier is arranged on surge to be suppressed the rear end, loop and carries out rectification, and this overvoltage breaking circuit is arranged between bridge rectifier two outputs and when the bridge rectifier output voltage surpasses the overvoltage thresholding, is off state, and this GS protective circuit then is arranged between electronic switch input and the control end and is used to protect electronic switch.

Further; This overvoltage breaking circuit comprises first voltage stabilizing didoe, first resistance, the 3rd resistance, the 6th resistance, first triode and second triode; This first voltage stabilizing didoe links to each other with the 6th resistance serial connection and is arranged between two outputs of bridge rectifier; The 3rd resistance one end links to each other with first voltage stabilizing didoe, and the other end links to each other with the base stage of first triode; This first resistance, one end links to each other with an output of bridge rectifier; The other end links to each other with the collector electrode of first triode and the base stage of second triode, and the emitter of this first triode and second triode all links to each other with another output of bridge rectifier.

Further, this GS protective circuit comprises second resistance, the 4th resistance and second voltage stabilizing didoe, and this second resistance and the 4th resistance serial connection links to each other and is arranged between the collector electrode of output and second triode of bridge rectifier; This second voltage stabilizing didoe then is connected in parallel on the second resistance two ends; This electronic switch then adopts the PMOS pipe, and its input and control end are connected to the two ends of second voltage stabilizing didoe.

Further, this CT power-supply circuit also comprises the halfwave rectifier filter circuit that is arranged between load circuit and the electronic switch.

After adopting said structure, the CT power-supply circuit of a kind of CT of reduction heating that the utility model relates to, compared with prior art; It no longer carries out capacitor filtering, but has increased an overvoltage breaking circuit after current transformer is handled through bridge rectifier; Thus, when voltage surpassed the overvoltage thresholding, electronic switch then can be closed condition; Promptly let and be the disconnection shape between load circuit and the CT power-supply circuit; Then dispel the heat through the big resistance of the equivalence in the overvoltage breaking circuit, its actual current has only 1-2mA again, and caloric value can be ignored; Thereby the long-term work that can guarantee whole electric power system is stable, and this GS protective circuit then plays the effect that the protection electronic switch is not damaged by high pressure.

Description of drawings

Fig. 1 is the common electrical block diagram of CT power taking;

The theory diagram of Fig. 2 a kind of CT power-supply circuit of the CT of reduction heating for the utility model relates to;

The physical circuit figure of Fig. 3 a kind of CT power-supply circuit of the CT of reduction heating for the utility model relates to.

Among the figure:

CT power-supply circuit 100

Surge suppresses loop 1 bridge rectifier 2

Overvoltage breaking circuit 3 GS protective circuits 4

Electronic switch 5 halfwave rectifier filter circuits 6

Load circuit 7

Surge suppresses loop 21 overload bleed-off circuits 22

Current rectifying and wave filtering circuit 23 linear voltage-stabilizing circuits 24

Load circuit 25.

Embodiment

In order further to explain the technical scheme of the utility model, come the utility model is set forth in detail through specific embodiment below.

As shown in Figure 2; The CT power-supply circuit 100 of a kind of CT of reduction heating that the utility model relates to; It comprises that surge suppresses loop 1, bridge rectifier 2, overvoltage breaking circuit 3, GS protective circuit 4 and electronic switch 5, and this surge suppresses loop 1 and directly links to each other with CT.

This bridge rectifier 2 is arranged on surge to be suppressed 1 rear end, loop and carries out rectification; 3 of this overvoltage breaking circuits are arranged between 2 liang of outputs of bridge rectifier; And it can be off state when bridge rectifier 2 output voltages surpass the overvoltage thresholding, and 4 of this GS protective circuits are arranged between electronic switch 5 inputs and the control end and are used to protect electronic switch 5.Preferably, this CT power-supply circuit 100 also comprises halfwave rectifier filter circuit 6, and this halfwave rectifier filter circuit 6 is arranged between load circuit 7 and the electronic switch 5, sees also Fig. 3, and it specifically is made up of diode D1, capacitor C 1 and capacitor C T1.

Like this, the utility model is through increasing an overvoltage breaking circuit 3, thus; When voltage surpassed the overvoltage thresholding, 5 of electronic switches can be closed condition, promptly let be the disconnection shape between load circuit 7 and the CT power-supply circuit 100; Then dispel the heat through the big resistance of the equivalence in the overvoltage breaking circuit 3 again; Its actual current has only 1-2mA, and caloric value can be ignored, thereby the long-term work that can guarantee whole electric power system is stable.More specifically; The utility model has changed the processing mode of CT excess energy; After making that promptly CT output energy satisfies need of load; CT loop and load circuit 7 break off, and CT can't export energy again, thereby have avoided traditional bleed-off circuit to cause CT to continue the problem that the output energy causes the serious heating in CT loop.

As shown in Figure 3; It is a kind of practical implementation circuit diagram of the utility model; Wherein, this overvoltage breaking circuit 3 comprises the first voltage stabilizing didoe D2, first resistance R 1, the 3rd resistance R 3, the 6th resistance R 6, the first triode Q2 and the second triode Q3, and this first voltage stabilizing didoe D2 links to each other with the 6th resistance R 6 serial connections and is arranged between two outputs of bridge rectifier 2; The 3rd resistance R 3 one ends link to each other with the first voltage stabilizing didoe D2, and the other end links to each other with the base stage of the first triode Q2; These first resistance R, 1 one ends link to each other with an output of bridge rectifier 2; The other end links to each other with the collector electrode of the first triode Q2 and the base stage of the second triode Q3, and the emitter of this first triode Q2 and the second triode Q3 all links to each other with another output of bridge rectifier 2.

In addition; 4 of this GS protective circuits comprise second resistance R 2, the 4th resistance R 4 and the second voltage stabilizing didoe D3, and this second resistance R 2 and the 4th resistance R 4 serial connections link to each other and are arranged between the collector electrode of output and the second triode Q3 of bridge rectifier 2; This second voltage stabilizing didoe D3 then is connected in parallel on second resistance R, 2 two ends; This electronic switch 5Q1 then adopts the PMOS pipe, and its input and control end are connected to the two ends of the second voltage stabilizing didoe D3.

Product form of the foregoing description and graphic and non-limiting the utility model and style, the those of ordinary skill of any affiliated technical field all should be regarded as not breaking away from the patent category of the utility model to its suitable variation or modification of doing.

Claims

1. one kind is reduced the CT power-supply circuit that CT generates heat; Comprise that the surge that confession links to each other with CT suppresses the loop; It is characterized in that; Also comprise bridge rectifier, overvoltage breaking circuit, GS protective circuit and electronic switch; This bridge rectifier is arranged on surge to be suppressed the rear end, loop and carries out rectification, and this overvoltage breaking circuit is arranged between bridge rectifier two outputs and when the bridge rectifier output voltage surpasses the overvoltage thresholding, is off state, and this GS protective circuit then is arranged between electronic switch input and the control end and is used to protect electronic switch.

2. a kind of CT power-supply circuit that reduces the CT heating as claimed in claim 1; It is characterized in that; This overvoltage breaking circuit comprises first voltage stabilizing didoe, first resistance, the 3rd resistance, the 6th resistance, first triode and second triode; This first voltage stabilizing didoe links to each other with the 6th resistance serial connection and is arranged between two outputs of bridge rectifier, and the 3rd resistance one end links to each other with first voltage stabilizing didoe, and the other end links to each other with the base stage of first triode; This first resistance, one end links to each other with an output of bridge rectifier; The other end links to each other with the collector electrode of first triode and the base stage of second triode, and the emitter of this first triode and second triode all links to each other with another output of bridge rectifier.

3. a kind of CT power-supply circuit that reduces the CT heating as claimed in claim 2; It is characterized in that; This GS protective circuit comprises second resistance, the 4th resistance and second voltage stabilizing didoe, and this second resistance and the 4th resistance serial connection links to each other and is arranged between the collector electrode of output and second triode of bridge rectifier; This second voltage stabilizing didoe then is connected in parallel on the second resistance two ends; This electronic switch then adopts the PMOS pipe, and its input and control end are connected to the two ends of second voltage stabilizing didoe.

4. a kind of CT power-supply circuit that reduces the CT heating as claimed in claim 1 is characterized in that this CT power-supply circuit also comprises the halfwave rectifier filter circuit that is arranged between load circuit and the electronic switch.