CN204142823U - A kind of measurement and protective device being applied to 10kV electric system - Google Patents

Abstract

A measurement and protection device applied to a 10kV power system, including a current transformer, one end of the current transformer is connected to the 10kV incoming line, the other end is connected to the 10kV bus, and the current transformer outputs current signals to the secondary measurement equipment; it also includes 3 Hall sensor, each Hall sensor includes a shell and a Hall sheet arranged on the surface of the shell, the upper part of the shell is a ring structure, the three-phase lines of the 10kV bus pass through the ring structure of the three Hall sensors, and the Hall Four lead wires a, b, c, and d are drawn out from the chip. The a and b leads of each Hall sensor are connected to the 220V excitation power supply, the c lead is connected to the secondary measurement equipment, and the d lead is grounded. The utility model can not only realize the function of traditional PT to measure line voltage, but also can effectively avoid various bad consequences caused by PT resonance.

Description

A Measuring and Protecting Device Applied in 10kV Power System

technical field

The utility model belongs to the technical field of power electronics, in particular to a measuring and protecting device applied to a 10kV power system. the

Background technique

Most of the voltage transformers (PT) in the 10kV power system are electromagnetic voltage transformers. Since the 10kV power system is a system with an ungrounded neutral point, single-phase grounding is a common temporary fault. When the phase-to-ground fault is eliminated, due to the change of system parameters, the PT iron core may be saturated and the inductive reactance will drop, and the capacitive reactance with the grid meets the resonance condition, so ferromagnetic resonance occurs at a certain frequency, resulting in overvoltage. In addition, the system voltage returns to normal when the intermittent arc at the single-phase grounding point is extinguished, and the system voltage changes again after the arc is re-ignited. Such a change in voltage is also the cause of system resonance. Ferromagnetic resonance and overvoltage will cause the primary high-voltage fuse of the PT to blow, and even cause the PT to be overheated and burned or damaged by insulation breakdown.

The PT resonant circuit can be simplified as a LC resonant circuit, in which the inductance L is the inductive reactance of the electromagnetic voltage transformer, and the capacitor C is the system capacitance. If a new sensor is used to replace the PT, the sensor can completely eliminate the inductance in the resonant circuit, then the condition of resonance will not be formed, and the generation of resonance will be eliminated in principle.

Utility model content

In order to solve the technical problems existing in the background technology, the utility model aims to provide a measurement and protection device applied to a 10kV power system, which can not only realize the function of PT measuring line voltage, but also effectively avoid various defects caused by PT resonance as a result of.

In order to realize above-mentioned technical purpose, the technical scheme of the utility model is:

Including a current transformer, one end of the current transformer is connected to the 10kV incoming line, the other end is connected to the 10kV busbar, and the current transformer outputs current signals to the secondary measuring equipment; it also includes 3 Hall sensors, each Hall sensor includes a housing and a setting The Hall plate on the surface of the shell, the upper part of the shell is a ring structure, the three-phase lines of the 10kV bus pass through the ring structure of the three Hall sensors respectively, and the Hall plate leads to four leads a, b, c, and d. The a and b leads of each Hall sensor are connected to the 220V excitation power supply, the c lead is connected to the secondary measurement equipment, and the d leads are grounded.

Wherein, the casing of the above-mentioned Hall sensor is encapsulated by epoxy resin.

Wherein, the Hall plate of the above-mentioned Hall sensor adopts a semiconductor single chip.

Wherein, the above-mentioned semiconductor single wafer is a silicon single wafer.

Wherein, the above-mentioned Hall sensor is installed under the busbar in the switch cabinet of the 10kV power system, and the installation method is a pillar installation method.

The beneficial effect brought by adopting the above-mentioned technical scheme:

The utility model adopts the Hall element to replace the traditional electromagnetic voltage sensor to detect the voltage signal of the 10kV bus, completely eliminates the inductance L in the LC resonant circuit, does not constitute a condition for resonance, eliminates the generation of LC resonance in principle, and avoids the LC resonance band adverse consequences to come.

Description of drawings

Fig. 1 is the circuit connection diagram of the utility model.

Fig. 2 is a schematic diagram of circuit connection of the Hall sensor of the present invention.

Fig. 3 is a schematic diagram of the Hall sensor of the present invention.

Detailed ways

The technical solutions of the present utility model will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the circuit connection schematic diagram of the utility model, a measurement and protection device applied to a 10kV power system, includes a current transformer (CT), one end of the current transformer is connected to a 10kV incoming line, and the other end is connected to a 10kV busbar. The current transformer outputs the current signal to the secondary measuring equipment. The function of CT is to convert the large current in the primary circuit into the standard small current in the secondary circuit through electromagnetic induction, which is convenient for the secondary measurement equipment to measure and protect the line.

As shown in Figure 2, the circuit connection schematic diagram of the Hall sensor of the utility model, the utility model also includes 3 Hall sensors, and the Hall sensor is installed under the busbar in the switch cabinet of the 10kV power system, and the installation method is a pillar type Installation method. The structural diagram of the Hall sensor is shown in Figure 3. Each Hall sensor includes a housing and a Hall plate arranged on the surface of the housing. The upper part of the housing is a ring structure, and the three-phase cables of the 10kV bus pass through three Hall sensors. The ring structure at the upper end, the four leads a, b, c, and d are drawn out from the Hall plate, the a and b leads of the three Hall sensors are connected to the 220V excitation power supply; the c leads of the three Hall sensors are connected to the secondary measurement equipment; The d leads of the 3 hall sensors are all grounded.

In this embodiment, the housing of the Hall sensor is encapsulated by epoxy resin. The Hall plate of the Hall sensor uses a silicon single chip.

The above embodiments are only to illustrate the technical ideas of the utility model, and cannot limit the protection scope of the utility model with this. Any changes made on the basis of the technical solutions according to the technical ideas proposed by the utility model all fall into the scope of the utility model. within the scope of the new protection.

Claims (5)

1. A measurement and protection device applied to a 10kV power system, including a current transformer, one end of the current transformer is connected to the 10kV incoming line, the other end is connected to the 10kV bus, and the current transformer outputs current signals to the secondary measurement equipment. Its characteristics It is: it also includes 3 Hall sensors, each Hall sensor includes a housing and a Hall plate arranged on the surface of the housing, the upper part of the housing is a ring structure, and the three-phase lines of the 10kV bus pass through the three Hall sensors respectively Ring structure, four lead wires a, b, c, d lead out from the Hall plate, the a, b lead wires of each Hall sensor are connected to the 220V excitation power supply, the c lead wire is connected to the secondary measurement equipment, and the d lead wires are all grounded. 2. A measurement and protection device applied to a 10kV power system according to claim 1, wherein the housing of the Hall sensor is encapsulated by epoxy resin. 3. A measurement and protection device applied to a 10kV power system according to claim 1, characterized in that: the Hall plate of the Hall sensor adopts a semiconductor single chip. 4. A measurement and protection device applied to a 10kV power system according to claim 3, wherein the semiconductor single chip is a silicon single chip. 5. A measurement and protection device applied to a 10kV power system according to claim 1, wherein the Hall sensor is installed under the busbar in the switch cabinet of the 10kV power system, and the installation method is a pillar type Installation method.