CN209375111U - Protective type CT electricity getting device for Microcomputer Protection - Google Patents

Abstract

The utility model discloses a protection-type current transformer power-taking device for microcomputer protection, which includes a protection-level CT transformer, a power-taking transformer, a protection sampling transformer, a DC stabilized voltage-taking output circuit, and a pressure-sensitive transformer for protection. Resistor VR and discharge tube GDT, the DC stabilized voltage output circuit includes a first rectification circuit, an inverter circuit and a second rectification circuit, the output end of the first rectification circuit is connected to the input end of the inverter circuit, and the output end of the inverter circuit Connected to the input end of the second rectification circuit, the secondary winding of the protective CT transformer, the primary winding of the power-taking transformer, and the primary winding of the protective sampling transformer are sequentially connected in series to form a circuit; the protective piezoresistor VR and the discharge tube GDT 1. The input terminal of the first rectification circuit of the DC voltage stabilized power-taking output circuit is connected in parallel with the secondary winding of the power-taking transformer. The utility model outputs low-power DC 200V power supply to supply power to the microcomputer protection device, so that it can work normally without power supply from PT and DC power supply screen.

Description

Protective current transformer power-taking device for microcomputer protection

technical field

The utility model relates to a current transformer power-taking device, in particular to a protection type current transformer power-taking device used for microcomputer protection, and belongs to the technical field of electric power equipment.

Background technique

Microcomputer protection devices are widely used in current power systems, and PT or DC power panels are generally used for power supply. The power supply system is complicated and the cost is high. And in some occasions, because there is no power supply facility, the microcomputer protection device cannot be used. When the PT is used for power supply, the PT will lose voltage when the power supply line is short-circuited, which will affect the normal operation of the microcomputer protection device, and the phenomenon that the output cannot be protected normally will cause the protection system to fail. Therefore, it is of great significance to develop a power-taking device to ensure that the microcomputer protection device can work normally without PT and DC power supply screen.

Utility model content

The purpose of this utility model is to provide a protective current transformer power-taking device for microcomputer protection, which is suitable for power supply of microcomputer protection devices in power systems, and solves the situation that the microcomputer protection devices existing in the prior art do not have PTs and DC power screens The following does not work properly.

The purpose of this utility model is achieved through the following technical solutions:

A protective current transformer power-taking device for microcomputer protection, including a protection-level CT transformer 1, a power-taking transformer 2, a protection sampling transformer 3, a DC stabilized voltage-taking output circuit 4, and a protective piezoresistor VR and discharge tube GDT, the DC stabilized voltage output circuit 4 includes a first rectifier circuit 5, an inverter circuit 6 and a second rectifier circuit 7, the output terminal of the first rectifier circuit 5 is connected to the inverter circuit 6 The input terminal, the output terminal of the inverter circuit 6 is connected to the input terminal of the second rectifier circuit 7, the secondary winding of the protection level CT transformer 1, the primary winding of the power-taking transformer 2, the protection sampling transformer 3 The primary windings are sequentially connected in series to form a circuit; the input terminal of the first rectifier circuit 5 of the protection piezoresistor VR, the discharge tube GDT, and the DC stabilized power output circuit 4 is connected in parallel with the secondary winding of the power transformer 2 .

The purpose of this utility model can also be further realized through the following technical measures:

The aforementioned protective current transformer power-taking device for microcomputer protection, wherein the power-taking transformer 2 uses EI iron core material with a power of 8W, the primary winding is 20 turns, and the secondary winding is 500 turns.

The aforementioned protective current transformer power-taking device for microcomputer protection, wherein the protective varistor VR adopts the parameter values of 250V AC continuous working voltage and 390V varistor voltage, and the discharge tube GDT adopts 420V DC breakdown voltage.

Compared with the prior art, the beneficial effect of the utility model is that the protective current transformer power-taking device for microcomputer protection of the utility model outputs a low-power DC 200V power supply to supply power to the microcomputer protection device. This device will not affect the normal operation of the protective CT, nor will it affect the secondary output of the protective CT through the protective sampling transformer to output the protective sampling signal; the microcomputer protection device can work normally without power supply from PT and DC power screen, Make the microcomputer protection device more widely used.

Description of drawings

Fig. 1 is a schematic circuit diagram of the utility model;

Fig. 2 is a circuit structure diagram of the DC stabilized voltage fetching output circuit of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the utility model is further described.

As shown in Figure 1, the utility model is used for the protection type current transformer power-taking device for microcomputer protection, including a protection-level CT transformer 1, a power-taking transformer 2, a protection sampling transformer 3, and a DC voltage stabilized power-taking output circuit 4. Protection varistor VR and discharge tube GDT, power transformer 2 adopts EI iron core material with a power of 8W, primary winding is 20 turns, secondary winding is 500 turns, varistor VR selects 250V AC for continuous operation The parameter value of voltage and 390V varistor voltage, the discharge tube GDT adopts 420V DC breakdown voltage.

The secondary winding of the protection level CT transformer 1, the primary winding of the power-taking transformer 2, and the primary winding of the protection sampling transformer 3 are sequentially connected in series to form a loop, and the secondary winding of the protection sampling transformer 3 outputs a protection sampling signal; As shown in Figure 2, the DC stabilized voltage output circuit 4 includes a first rectifier circuit 5, an inverter circuit 6 and a second rectifier circuit 7, the output terminal of the first rectifier circuit 5 is connected to the inverter circuit 6 The input terminal, the output terminal of the inverter circuit 6 is connected to the input terminal of the second rectifier circuit 7, the input terminal of the first rectifier circuit 5 of the varistor VR, the discharge tube GDT, the DC stabilized voltage output circuit 4 is connected to the input terminal of the first rectifier circuit 5. The secondary windings of the electric transformer 2 are connected in parallel.

Protective grade CT transformer 1 selects the rated ratio 5A, and the primary current works at 10% of the rated value. The secondary winding output of protective grade CT transformer 1 is 0.5A, and the primary winding input of power-taking transformer 2 is 0.5A. Ratio conversion, its secondary winding can output 20mA current, which can meet the working power demand of the microcomputer protection device. When the primary current works at the rated value, the secondary winding of the protective CT transformer 1 outputs 5A, the primary winding of the power-taking transformer 2 outputs 5A, and the secondary winding can output 200mA. The power transformer 2 is output as a current source, and after being processed by the DC stabilized voltage output circuit 4, a 200V DC stabilized power supply is output. The function of the piezoresistor VR and the discharge tube GDT is: when the output circuit 4 of the DC stabilized voltage taking power fails, it prevents the output of the secondary winding of the power taking transformer 2 from being open, and can release the instantaneous overcurrent and limit the overvoltage. Ensure the working safety of the power transformer 2. Since the microcomputer protection device has high requirements on the power supply, the power transformer 2 obtains AC power, which is rectified into DC power by the first rectification current 5, and then the DC power is converted into AC by the inverter circuit 6, and finally by the second rectifier circuit 7 The alternating current is rectified into the direct current voltage of the microcomputer protection device. In this way, the DC power supply of the external strong current system can be completely isolated from the power supply of the weak current system of the microcomputer protection device. Therefore, the inverted DC power supply has strong anti-interference ability, and can completely isolate strong interference from various reasons such as tripping or closing of circuit breakers in the substation.

In addition to the above-mentioned embodiments, the utility model can also have other implementation modes, and all technical solutions formed by equivalent replacement or equivalent transformation all fall within the scope of protection required by the utility model.

Claims (3)

1. A protective current transformer power-taking device for microcomputer protection, characterized in that it comprises a protection grade CT transformer (1), a power-taking transformer (2), a protection sampling transformer (3), a DC stabilizer A voltage-feeding output circuit (4), a protective piezoresistor VR and a discharge tube GDT, the DC stabilized voltage-feeding output circuit (4) includes a first rectifier circuit (5), an inverter circuit (6) and a second A rectification circuit (7), the output terminal of the first rectification circuit (5) is connected to the input terminal of the inverter circuit (6), and the output terminal of the inverter circuit (6) is connected to the input of the second rectification circuit (7) end, the secondary winding of the protection level CT transformer (1), the primary winding of the power-taking transformer (2), and the primary winding of the protection sampling transformer (3) are sequentially connected in series to form a circuit, and the protective piezoresistor VR , the discharge tube GDT, the input end of the first rectifier circuit (5) of the DC voltage stabilization output circuit (4) and the secondary winding of the power transformer (2) are connected in parallel. 2. the protective current transformer power-taking device that is used for microcomputer protection as claimed in claim 1, is characterized in that, described power-taking transformer (2) adopts the EI iron core material that power is 8W, and primary winding is 20 turns, the secondary winding is 500 turns. 3. The protective current transformer power-taking device for microcomputer protection as claimed in claim 1, wherein the protective varistor VR selects the parameter values of 250V AC continuous operating voltage and 390V varistor voltage, The discharge tube GDT adopts 420V DC breakdown voltage.