CN102759681A - Transformer core ground fault monitoring device - Google Patents

Abstract

The invention provides a transformer core ground fault monitoring device, which includes a current transformer, a casing, a display screen and a measurement circuit arranged inside the casing, and the measurement circuit is connected to the current transformer and the display screen ; The measurement circuit includes a current/voltage conversion unit, an amplifying circuit, an A/D conversion unit, an operation control unit, an alarm unit, a display unit and a wireless transmission unit, and the current transformer clamp is clamped on the ground lead of the transformer core and connected to the current/voltage conversion unit, the amplifying circuit is respectively connected to the A/D conversion unit and the current/voltage conversion unit, and the operation control unit is respectively connected to the A/D conversion unit, the display unit, the alarm unit and the wireless sending unit, the display screen of the display unit is set on the panel of the housing. The invention has the advantages of simple structure, accurate measurement and safe use.

Description

Transformer Core Ground Fault Monitoring Device

technical field

The invention belongs to the technical field of current and voltage monitoring, and in particular relates to a transformer core grounding fault monitoring device.

Background technique

The grounding current of the iron core of the transformer in the running state is very small, about a few milliamps to tens of milliamperes, but when the multi-point grounding fault occurs in the transformer core, the grounding current of the iron core increases rapidly to A few amps or even dozens of amps will cause the partial iron core of the transformer to overheat, which will cause the decomposition of oil, generate flammable gas, fuse the grounding wire, burn out the iron core, cause the potential of the iron core to float, cause discharge, and eventually cause the main body of the transformer to burn out. Fault. At present, the commonly used methods for monitoring multi-point grounding faults of transformer cores are: 1. Directly measure the insulation resistance of the core to the ground under the condition of temporary power failure of the transformer. However, the power failure detection of the transformer will seriously affect the life and production activities of the end users. To ensure the reliability of power supply, the method of temporary power outage is not in line with the purpose of providing high-quality power supply services. 2. On-site personnel use clamp ammeters to monitor its current. The biggest disadvantage of the monitoring method of using clamp ammeters to measure the current of the transformer grounding wire is that it cannot respond to the fault immediately, and there is a serious hidden danger of further expansion of the accident; and because the transformer is strong Due to the interference of the magnetic field, the measured value is very inaccurate, and even several measured values at the same measurement point are very different.

In order to solve the above existing problems, people have been seeking an ideal technical solution.

Contents of the invention

The object of the present invention is to address the deficiencies of the prior art, thereby providing a transformer core grounding fault monitoring device with simple structure, rapid response, accurate measurement, easy operation, safe use and strong practicability.

In order to achieve the above object, the technical solution adopted by the present invention is: a transformer core ground fault monitoring device, which includes a current transformer, a housing, a display screen and a measuring circuit arranged inside the housing, the measuring circuit Connect the current transformer and the display screen respectively; the measurement circuit includes a current/voltage conversion unit, an amplification circuit, an A/D conversion unit, an operation control unit, an alarm unit, a display unit and a wireless transmission unit; the current The transformer clamp is clamped on the ground lead wire of the transformer core to sense and collect the ground current signal of the transformer core; the output end of the current transformer is connected to the input end of the current/voltage conversion unit to convert the collected The ground current signal is converted into a voltage signal; the output end of the current/voltage conversion unit is connected to the input end of the amplifying circuit to amplify the voltage signal; the output end of the amplifying circuit is connected to the input end of the A/D conversion unit to The analog voltage signal is converted into a digital voltage signal; the operation control unit is connected to the output terminal of the A/D conversion unit to analyze the converted digital voltage signal, perform operation processing to obtain an effective transformer core ground current value, and thereby Send corresponding control signals; the display screen of the display unit is set on the panel of the housing, the display unit is connected to the operation control unit to display the effective transformer core ground current value; the alarm unit is connected to the The operation control unit is used to send an alarm signal; the operation control unit is connected to the wireless sending unit to send the effective transformer core grounding current value to the remote monitoring system through the wireless communication network.

Based on the above, the current transformer is a clamp current transformer with a precision of 1%; the model of the current-voltage conversion chip of the current/voltage conversion unit is MAX4072; the amplifier circuit is an operational amplifier circuit for amplifying voltage signals.

Based on the above, the model of the A/D conversion chip in the A/D conversion unit is ADS8557. the

Compared with the prior art, the present invention has outstanding substantive features and significant progress. Specifically, the present invention has the following features: 1. The monitoring device realizes the purpose of real-time display of transformer core grounding current through simple circuit combination, so that Monitoring personnel can grasp the working status of the transformer at any time, avoiding the shutdown detection of the transformer, and saving manpower and material resources. 2. The monitoring device uses a clamp-type current transformer, which is directly clamped on the grounding wire of the transformer core, which is convenient and simple. 3. The monitoring device is connected to the remote monitoring system through the wireless sending unit, and the effective grounding current value of the transformer core is sent to the display device of the remote monitoring system for real-time display, so that the monitoring personnel do not need to go to the site for data collection. You can intuitively obtain the reading of the transformer core ground current.

Description of drawings

Fig. 1 is a schematic structural view of the present invention.

Figure 2 is a block diagram of the measurement circuit.

Detailed ways

The technical solutions of the present invention will be described in further detail below through specific implementation methods.

As shown in Figure 1, a transformer core ground fault monitoring device, it includes a current transformer 1, a housing 2, a display screen 3 and a measurement circuit arranged inside the housing 2, the measurement circuit is respectively connected to the The current transformer 1 and the display screen 3 .

As shown in Figure 2, the measurement circuit includes a current/voltage conversion unit, an amplification circuit, an A/D conversion unit, an operation control unit, an alarm unit, a display unit and a wireless transmission unit, and the current transformer 1 is clamped on the transformer The grounding lead wire 4 of the iron core is used to inductively collect the grounding current signal of the transformer core; the output end of the current transformer is connected to the input end of the current/voltage conversion unit to convert the grounding current signal of the collected transformer core into Voltage signal; the output end of the current/voltage conversion unit is connected to the input end of the amplifying circuit to amplify the voltage signal; the output end of the amplifying circuit is connected to the input end of the A/D conversion unit to convert the analog voltage signal It is a digital voltage signal; the operation control unit is connected to the output terminal of the A/D conversion unit to analyze the converted digital voltage signal, perform operation processing to obtain an effective transformer core ground current value, and then send a corresponding control signal The display screen 3 of the display unit is arranged on the panel of the housing 2, and the display unit is connected to the operation control unit to display the effective transformer core grounding current value; the alarm unit is connected to the operation control unit The unit sends out an alarm signal to immediately notify the on-site maintenance personnel to eliminate the accident.

The current transformer used is a clamp-type current transformer with an accuracy of 1% and a measuring current range of 0-20A, which is suitable for clamping on the grounding lead of the transformer iron core; the current-voltage conversion chip of the current/voltage conversion unit The model is MAX4072; the amplifier circuit is an operational amplifier circuit for amplifying voltage signals; the model of the A/D conversion chip in the A/D conversion unit is ADS8557.

The operation control unit is connected to the wireless sending unit, and the effective transformer core grounding current value is sent to the remote monitoring system through the wireless communication network, so that it can be displayed on the display device of the remote monitoring system, so that the operation of the control room in the remote monitoring system The personnel can intuitively obtain the effective value of the ground current of the transformer iron core, which is beneficial for the operator to grasp the current working state of the transformer.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications to the specific implementation of the invention or equivalent replacement of some technical features; without departing from the spirit of the technical solution of the present invention, should be included in the scope of the technical solution claimed in the present invention.

Claims (3)

1. A transformer core ground fault monitoring device, comprising a current transformer, a housing, a display screen and a measurement circuit arranged inside the housing, the measurement circuit is connected to the current transformer and the display screen respectively, It is characterized in that: the measurement circuit includes a current/voltage conversion unit, an amplifying circuit, an A/D conversion unit, an operation control unit, an alarm unit, a display unit and a wireless transmission unit; the current transformer is clamped on the iron core of the transformer The grounding current signal of the transformer iron core is collected by induction on the grounding lead; the output end of the current transformer is connected to the input end of the current/voltage conversion unit to convert the grounding current signal of the collected transformer iron core into a voltage signal; The output end of the current/voltage conversion unit is connected to the input end of the amplifying circuit to amplify the voltage signal; the output end of the amplifying circuit is connected to the input end of the A/D conversion unit to convert the analog voltage signal into a digital voltage signal ; The operation control unit is connected to the output end of the A/D conversion unit to analyze the converted digital voltage signal, and the operation processing obtains an effective transformer core ground current value to send a corresponding control signal; the display The display screen of the unit is set on the panel of the housing, the display unit is connected to the operation control unit to display the effective transformer core grounding current value; the alarm unit is connected to the operation control unit to send an alarm signal; The operation control unit is connected with the wireless sending unit to send the effective transformer iron core grounding current value to the remote monitoring system through the wireless communication network. 2. The transformer core ground fault monitoring device according to claim 1, characterized in that: the current transformer is a clamp current transformer with an accuracy of 1%; the current-voltage conversion chip of the current/voltage conversion unit The model is MAX4072; the amplifier circuit is an operational amplifier circuit for amplifying voltage signals. 3. The transformer core ground fault monitoring device according to claim 1, characterized in that: the model of the A/D conversion chip in the A/D conversion unit is ADS8557.

Images