1. Xsn-400a zinc oxide arrester resistive current tester measurement principle is what?
A: The use of digital signal processing and harmonic analysis technology, the application of Fourier transform technology, through the current signal and PT voltage signal sampling, the full current of the resistive current separation, to achieve the measurement of resistive current.
2. Why is the main measurement parameter resistive current rather than total current?
Answer: because impedance current can produce active power (active power is the calorific value), the lightning arrester of be affected with damp be affected with damp, aging failure, such as its resistance current will increase sharply, and most of all current for capacitive current, the capacitive current of reactive power, reactive power does not produce heat, the stand or fall of its data arrester in the reaction.
3 VS400A zinc oxide arrester resistive current tester test parameters are what?
A: Full current, resistive current, fundamental wave resistive current, 3, 5, 7 harmonic resistive current, active power, system voltage, etc. Note: Active power and system voltage cannot be measured without PT measurement.
4. How to judge whether the data of zinc oxide arrester is qualified?
Answer: take and initial data commonly (or one year data) compare method, if measure data is 150% of initial data, increase measure times, if measure data is 200% of initial data, answer to tear down arrester, undertake further measure. Statistics before the 1990s, the accident rate of zinc oxide arrester is 0.219 phase / 100 phase · year.
5. If there is no initial data, how to judge whether the arrester is good or bad?
Answer: There is no initial data, you can judge the quality of the lightning arrester according to the phase Angle of voltage and current of the arrester (hereinafter referred to as phase Angle). Generally, the phase Angle of the new lightning arrester is 85°, while the phase Angle of the troublefree lightning arrester in operation is 80°-85°. WS400A can display this Angle directly. If not, it can be calculated according to the following formula:
Theta equals the Arc cosine / 1.414 / Ix (Ir)
Where: θ - phase Angle
Ir - Peak resistive current
Ix -- Effective value of full current
To put the above content in a simple way: the peak value of the resistive current is about 1/5 of the effective value of the full current, so that the arrester can be judged as a fault-free arrester and the data can be used as the initial value of the arrester.
6. How do you connect the current test line of your instrument? Does this connection affect the accuracy of the data?
A: The current test line of the instrument is connected to both ends of the discharge counter. The internal resistance of the general discharge counter is dozens of ohms, and the internal resistance of the instrument current channel is about zero (only the test line resistance), so it is equivalent to short-circuit the discharge counter with the instrument, almost all the current passes from the inside of the instrument, so the counter does not image the accuracy of the current data.
7. How to judge whether the current line is connected properly before measurement?
Answer: After wiring, the discharge counter should be short-circuited, so the counter pointer should return to zero. If the pointer does not return to zero, it indicates that the test line is not properly connected. However, the following problems should be noted: (1) During three-phase measurement, phase A will definitely return to zero, and phase B/C will return to zero only when the phase is measured. ② Single phase measurement B/C phase, only when the measurement counter will return to zero. ③ When some counters are damaged, the pointer may not return to zero.
8. How do you connect the voltage test line of your instrument? Is it safe to do this?
Answer: The voltage test line is connected to the secondary test of PT 100 / SQRT (3)=57.74V, in order to protect PT safety, the instrument has three protection measures: ① The internal resistance of the voltage channel is 120K ω, and the current through it is about 0.05mA. ② The voltage channel is completely isolated from the instrument, and PT failure will not be caused by misoperation or damage of the instrument. (3) The top of the test line is connected with 0.2a fuse, which will not lead to PT short circuit because of the damage of the test line.
9. What is the principle of pT-free measurement?
Answer: HS2400 no PT harmonic analysis principle, through the current signal of high order harmonic content analysis, can probably understand the phase relationship between the fundamental wave current and voltage signal, so as to get resistive current, its accuracy is affected by the content of harmonic voltage signal, general error (and have PT comparison) is not more than 10%. Three-phase measurement and application of three phase comparison method, theoretically A, B, C phase three qualified lightning arrester in the running state (not calculated and interference) 180 degrees to its current phase, if one phase impedance increase current phenomenon in A lightning arrester, so its phase Angle deviation, necessarily instrument based on three-phase arrester phase difference of the sampling, If there is a surge arrester with data significantly inconsistent with the other two phases, intensive monitoring and further accurate measurements are required.
10. Battery maintenance methods?
Answer: The built-in battery used by the instrument is lithium ion. Like most lithium ion batteries, the following matters should be noted in use: ① The instrument should be fully charged when unused, and it should be charged once every three months. ② Make sure the power switch is off after using the instrument. ③ Avoid working or storing the instrument in places where the temperature is too high or too low.
11. What is the data trend of the arrester's resistive current under the action of interphase interference?
Answer: Under the influence of interphase interference, A phase data is relatively large, while C phase data is relatively small. B phase data is basically not affected by interphase interference.
