CN201229381Y - Anomalous frequency test system for ground resistance of grounded screen - Google Patents

Abstract

The utility model relates to an earth resistance different frequency testing system of grounding systems, which is composed of a different frequency power supply (1), a sensor (2), a filter circuit (3), an A/D collecting chip (4), a single chip microcomputer (5) and a touch screen (6) which are connected in series in turn. The system converts a voltage current signal into a signal in the sampling range of the collecting chip through the sensor (2). The earth resistance different frequency testing system has the beneficial effects that firstly, different frequencies can be selected to compare, the system chooses and follows what is right, the system has enough strength to eliminate interference, secondly, the signal filtering rate highly reaches 99.8%, thirdly, the sampling precision is high, the testing precision of the earth resistance is high, fourthly, the system is light and is convenient for use, and fifthly, the system can switch circuits automatically and can effectively guarantee that tested data is accurate.

Description

Resistance of Grounding Grids alien frequencies test macro

Technical field

The utility model belongs to the electric power project engineering field, relates in particular to a kind of Resistance of Grounding Grids alien frequencies test macro, and this system is specially adapted to test the Resistance of Grounding Grids resistance of generating plant or transformer station.

Background technology

Lay grounded screen in generating plant and transformer station, fundamental purpose is in order to take precautions against natural calamities, and is in order to guarantee personal safety and device security is not struck by lightning or the infringement of other short trouble.In order to ensure the safety of the person with property, CNS requires the stake resistance resistance of grounded screen necessary up to standard.Therefore,, all must carry out the test of Resistance of Grounding Grids resistance in time, whether satisfy request of national standard with this tested regional Resistance of Grounding Grids of checking to the grounded screen or the grounded screen after operation a period of time of newly laying.And a kind of Resistance of Grounding Grids test macro that is referred to as the power frequency method of known current use but in use is subjected to the interference of power frequency component easily, so just makes that the resultant error of measuring is very big.And if adopt the very big result of this error to go to verify whether the resistance of being tested Resistance of Grounding Grids meets the requirements, very likely cause the security incident and even the personal safety accident of this grounded screen surrounding devices.

The utility model content

The technical problems to be solved in the utility model is: at the defective of known technology existence, a kind of Resistance of Grounding Grids alien frequencies test macro is provided, use this system, can accurately test Resistance of Grounding Grids, whether the resistance of verifying this stake resistance satisfies the rules requirement, and then effectively ensures the safety of the person and electrical equipment.

Technical solution of the present utility model is that described Resistance of Grounding Grids alien frequencies test macro as shown in Figure 1, is composed in series in regular turn by alien frequencies power supply 1, sensor 2, filtering circuit 3, A/D acquisition chip 4, single-chip microcomputer 5 and touch-screen 6.

The effect of the sensor 2 in the native system said structure is, by it, can realize the conversion of voltage and current signal, is about to voltage and current signal and changes into signal in the acquisition chip sample range; Filtering circuit 3 should select classical Order RC circuit for well.The concrete parameter of this Order RC circuit is, resistance R is 51,000 Europe resistance, and capacitor C is 1 microfarad electric capacity; The MAX197 cake core that described A/D acquisition chip 4 generally adopts MAX company to produce carries out data acquisition is advisable, and this chip can carry out 8 passage synchronous acquisition; Described single-chip microcomputer 5 is a signal processing, is mainly used to image data is carried out effective value calculating, resistance calculating and differentiation.Signal processing chip generally adopts the W77E58 type single-chip microcomputer of Hua Bang company, and its touch-screen 6 is a liquid-crystal display section in fact.Come therefrom to realize simultaneously to show and the class keyboard operation.

The calculating of stake resistance resistance: the electric current and voltage data of utilize gathering can calculate the included angle of the effective value I of the effective value U of voltage and electric current and voltage, electric current.Like this, the size of impedance ground is: Z=U/I, the size of stake resistance is: R=U * cos φ/I.

The beneficial effects of the utility model are:

1), the employing of the alien frequencies power supply of frequency adjustable, make the tester can in test process, choose different frequencies and compare, choose what is good to follow.Moreover the output current of alien frequencies power supply can reach more than the 10A, has enough dynamics to eliminate on-the-spot the interference;

2), interference eliminated is thorough, 50Hz power frequency component rejection rate is up to 99.8%;

3), the sampling precision height, earth loop impedance test precision height;

4), the employing of touch-screen makes system more light and handy, easy to use;

5) but, the built-in sensors automatic switch-over circuit of native system, native system also can be selected the sensor of different ranges automatically according to measured parameter, thereby has guaranteed the accuracy of different electric currents and the following data of surveying of different voltages effectively.

Description of drawings

Fig. 1 is the structured flowchart of a specific embodiment of the utility model Resistance of Grounding Grids alien frequencies test macro, is denoted as among the figure:

1-alien frequencies power supply,

2-sensor,

3-filtering circuit,

4-A/D acquisition chip,

5-single-chip microcomputer,

6-touch-screen.

Embodiment

Referring to Fig. 1, Figure 1 shows that specific embodiment of the utility model Resistance of Grounding Grids alien frequencies test macro.The alien frequencies power supply 1 of this embodiment adopts Hunan China to economize the HYJC-3000 type alien frequencies power supply that the pure Power Tech Corp. Inc. of remittance produces; Built-in sensors 2 adopts a PT51C002 type 300V/3.5V voltage sensor of being produced by Chinese Sichuan Wei Bo company and a PT51C002 type 150V/3.5V voltage sensor, a PT51C002 type 75V/3.5V voltage sensor, a PT51C002 type 20V/3.5V voltage sensor, a CT53C902 type 20A/3.5V current sensor, a CT53C902 type 10A/3.5V current sensor, the sensor groups that CT53C902 type 5A/3.5V current sensor is formed in parallel of being produced by above-mentioned same company.So, just can be in test process, according to the size of measured signal, the sensor that automaticallyes switch and adapt, so as to the size of control measured signal in more than 1/3 of range of the sensor of routine, for measuring accuracy is given security; Sensor 2 becomes 5V to flow to filtering circuit 3 with interior AC signal conversion of signals the power frequency interference signals of 50Hz is considered to remove.This filtering circuit 3 is a typical commercially available Order RC filtering circuit, and the resistance of its resistance R is 51,000 Europe, and the capacity of capacitor C is 1 microfarad; The A/D acquisition chip 4 of present embodiment adopts U.S. MAX company to produce MAX197 type acquisition chip; Single-chip microcomputer 5 adopts U.S. Hua Bang company to produce the little process chip of W77E58 type.This single-chip microcomputer 5 is to each passage weekly after 32 discrete datas of phase synchronous acquisition, calculates the size of impedance ground and stake resistance according to the aforementioned calculation mode, and diagnostic result is presented on the touch-screen 6.This result also can become the output of paper spare by printer prints.Above-mentioned touch-screen 6 adopts China Shenzhen Guia Hill company to produce CA320240F type 320 * 240 dot matrix touch-screens.

The Resistance of Grounding Grids alien frequencies test macro of the present utility model of said structure is proved to be respond well through manufacturing experimently to try out, and is esy to use, safe and reliable, reaches designing requirement fully.

Claims (1)

1, a kind of Resistance of Grounding Grids alien frequencies test macro is characterized in that, it is composed in series in regular turn by alien frequencies power supply (1), sensor (2), filtering circuit (3), A/D acquisition chip (4), single-chip microcomputer (5) and touch-screen (6).

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