Line Impedance Measurement

Line Impedance Measurement device integrated with pilot frequency power supply and host . In other words, pilot frequency power supply and output control, isolation transformer and its tap switch,test wiring change,ground switching control, signal measurement and acquisition, data analysis and calculation function are combined in once case .

It covers all required tested items on power lines , such as a) measurement of Line induced voltage, ground current. b) Check phase, insulation resistance and DC resistance measurement. C)Positive sequence impedance, zero sequence impedance, positive sequence capacitance, zero sequence capacitance of three phase transmission line. d) Zero sequence mutual impedance and zero sequence coupling capacitance between multiple homo-bar or parallel circuit circuits.

In the field measurement, according to the test objects and test items, the corresponding program built in the host can control the transformation of test wiring (including grounding operation, etc.), output of isolating transformer (frequency, voltage), data sampling, calculation and analysis in turn.

The chassis adopts frame-type structure, gusset plate installation, display screen, printer, keyboard, power supply indicator, power start button, alarm light, USB, etc. are concentrated on the front.The external wiring terminals are concentrated on the back of the case and recessed below the back plane. Three external current input terminals are drawn from the wiring board, which are used to access the standard source calibration device for measuring accuracy during instrument verification.

The dimension of the equipment conforms to the principle of ergonomics. The tester can operate the instrument when stand, Handling handles are installed on two sides of the chassis, and the bottom of the chassis can be embedded in a flat car with universal casters for transportation, on-site loading, unloading, and moving. The weight of the whole test device is controlled within 60 ~ 85kg according to the model and specification.

Hot tags: Transmission line parameter tester, transmission line test system

1. The device is equipped with high internal resistance induction voltage measuring element, which can quickly and accurately measure the power frequency electrostatic voltage, electromagnetic voltage and phase Angle of three-phase and two-phase transmission lines. At the same time, the device can measure the ground current (electromagnetic induction current and capacitive current) and phase Angle of each phase of the line under the condition of earthing and open circuit.

2. It can test positive sequence impedance, zero sequence impedance, positive sequence capacitance, zero sequence capacitance and other parameters of three-phase and two-phase transmission lines (railway traction transformer power supply lines, DC transmission lines and DC ground pole lines). The switch of wiring at the first end of the line test is completed automatically in the device. Only one wiring of the line is needed to complete all the test items, which greatly improves the work efficiency of the field test.

3. A three-phase large-current relay is installed in the device to automatically control the grounding operation of the road side of the front end of the tested line,cooperate with the transformation and signal acquisition of positive sequence and zero sequence parameters test during wiring. No need any manual switching of the front end to test the connection, to avoid the damage to the tester due to the induced voltage of the line during the change of the connection, thus ensuring the safety of the instrument.

4. The device has 8 independent measuring channels of voltage and current, which ensures that the single phase mutual inductance and coupling parameters of the line can be obtained at one time while the zero-sequence mutual impedance and zero-sequence coupling capacitance tests are carried out between the circuits of the same rod or parallel lines.

5.With strong anti-interference ability, the specially designed power frequency interference suppression device in the device can resist the normal test of line parameters under the condition that the ground induction current is less than 100A after the first and last two ends of the line under test are grounded. The principle of resistance to power frequency interference is that the isolation transformer of the device is specially designed with an induction voltage suppression module to form a low-resistance discharge channel to the ground.

6.The test frequency of line impedance parameter is 45Hz and 55Hz, which has better test equivalence.The capacitance test frequency is adjusted to 260Hz single frequency test, which solves the problem of measuring accuracy of capacitance parameters of ultra-short distance line.

7. The pilot frequency power supply has good fineness step boost control,the output voltage and current of the off-frequency power supply can be automatically adjusted through the precheck program, which solves the problem of parameter testing for ultra-short lines and large-section cables.

8. The latest mathematical algorithm and 16-bit high-precision AD chip are adopted to ensure the purity and high fidelity of the output signal of the device at different frequencies.Under the condition that the test signal and interference signal are 1:20 times, the different frequency test signal and power frequency interference signal can be completely separated accurately, so as to accurately calculate the line power frequency parameters.

9. The test device adopts single-phase 220V power supply mode, which facilitates the access of on-site working power supply and the use of single-phase generator power supply to complete all the test items, and has the function of alarm protection when the working power is mistakenly connected to 380V.

10. High reliability, the pilot frequency power supply with over voltage, over current, short circuit, overheating and other multiple protection.The operation panel is equipped with a manual emergency stop button, which ensures that the test power output can be turned off manually in case of any accident in the parameter test site. Meanwhile, the device automatically ground the first-end line three-phase, ensuring the safety of the equipment and testers.

11. The device is equipped with the function of testing grounding performance, which can not only ensure the power supply of the device does not start and output in the case of bad grounding, but also avoid the occurrence of zero sequence impedance parameter test deviation of the line due to bad grounding.

12.The instrument is equipped with a calendar chip and a large capacity memory, which can automatically save the test results according to the test number or time sequence, check the history at any time, and print out.

13. The stored data of the instrument can be exported by USB flash disk through the device panel, and it is convenient for users to manage the test data and edit the test report of line power frequency parameters on any PC.

1. According to the selection and configuration table of the test system, specifications and models suitable for different power frequency interference intensity and line length are selected to meet the test requirements for ac power frequency parameters of 0.2 ~ 1500km overhead lines or cable lines.

2. Anti-power frequency interference:Under the condition that the ratio of output signal to power frequency interference signal is 1:20, the output is reliable and stable, and the power frequency interference signal is separated accurately and all test items are completed.

3. Power supply: single-phase AC 220V±10%, (10 ~ 40A) 50Hz±2%

4. Protect function

1) Working power protection: When the input power of the instrument is mistakenly connected to the 380V power supply, the overvoltage alarm indicator will light up and the buzzer will send an alarm prompt.

2) Housing grounding and testing grounding detection :when the grounding is bad, the device will send an alarm prompt and turn off the power output.

3) It has an emergency stop button, which can cut off the power output and ground the first end of the line under test in case of accident, so as to protect the safety of testers and equipment.

4) Other protection: The device has four kinds of protection: overvoltage, overcurrent, short circuit and overheat. Fault indicator light is installed on the panel to indicate the fault type.

5. Output characteristics of pilot frequency power supply:

1) Output frequency：45Hz/55Hz/260Hz the frequency is better than ±0.1%.

2）Output waveform: standard sine wave, waveform distortion is better than ±2%;

6.Test accuracy ：

1）Electrostatic induction test: Measurement accuracy: ±5%±5 digits Max resolution: 0. 001kV

2）Electromagnetic voltage test: Measurement accuracy:±0.2%±2 words Max resolution:0. 001V

3) Current test: measurement accuracy ±0.2%±2 words highest resolution 0.01mA

4) Capacitance test: Highest resolution: 0.0001 F

≥0.1 F, ±1% reading ±5 characters;< 0.1 F, ±2% reading ±5 words;

5) Impedance parameters test: the highest resolution: 0.001 Ω

≥1Ω,±1% reading ±5 characters; ＜1Ω,±2% reading ±5 words;

Impedance Angle: 0° ~ 360°, ±1% reading ±0.05°

7.Different models