CN105445583A - Transformer station lightning arrester test method - Google Patents

Abstract

The invention relates to the lightning arrester test technology and particularly relates to a transformer station lightning arrester test method. The transformer station lightning arrester test method comprises steps of cleaning the surface of the lightning arrester and detecting whether damages exist and whether two end heads are loosen or corroded, detecting the lightning arrester conditions of internal damping and porcelain sleeve cracking, detecting whether the contact of the parallel connection resistor is sound or whether the parallel connection resistor is aged and spoiled or broken, detecting insulation resistance, detecting conduction current, converting the temperature of the conduction current, and measuring the power frequency discharge. The transformer station lightning arrester test method is applicable to the FZ series valve type lightning arrester and eliminates the safety hidden danger of the lightning arrester.

Description

A test method for substation lightning arrester

technical field

The invention relates to a lightning arrester test technology, in particular to a test method for a substation lightning arrester.

Background technique

Arresters include tubular arresters, valve arresters and zinc oxide arresters. The arrester is usually connected between the wire and the ground, and connected in parallel with the protected equipment. When the protected equipment is running under the normal working voltage, the arrester does not act, that is, it is regarded as an open circuit to the ground. Once an overvoltage occurs and endangers the insulation of the protected equipment, the arrester will act immediately to guide the high-voltage surge current to the ground, thereby limiting the voltage amplitude and protecting the insulation of the electrical equipment. When the overvoltage disappears, the arrester quickly returns to its original state, so that the system can supply power normally.

Most of the arrester tests are carried out before the thunderstorm season and after overhaul or when necessary. There has never been a specification description for the test method of the arrester in the prior art. Different substations have different test methods. At present, most substations do not There are no specific regulations, and the specifications and constraints for the test are poor. The test results of the arrester directly affect the quality of the arrester, and the inaccurate results may even affect the safety of the entire substation.

Contents of the invention

The present invention provides a method for testing lightning arresters in substations, which solves the problem of irregular testing of lightning arresters in the prior art. The specific technical solutions are as follows:

A method for testing a substation lightning arrester, comprising the steps of:

S1 Clean the surface of the arrester, check whether there is any trauma, and whether the two ends are loose and rusted;

S2 Check the moisture inside the arrester and the cracks of the porcelain sleeve, and check whether the parallel resistance is in good contact, whether it is aged, deteriorated and broken;

S3 Insulation resistance test: Use a 5000V insulation resistance meter to measure the insulation. For a multi-component arrester, each component should be individually measured for its insulation resistance to the ground;

S4 Measure conductance current: use the half-wave rectification method, step up the voltage through the voltage regulator transformer to obtain AC high voltage, and then pass the rectification element into DC high voltage and add it to the side of the arrester to be tested, and use the milliampere meter to approach the high voltage side of the arrester To measure the conductance current, add a filter capacitor with a capacitance above 0.1nF to the high-voltage rectification circuit, and use an electrostatic voltmeter to measure the DC test voltage in the rectification circuit;

S5 Temperature conversion of conductance current: The conductance current is related to temperature, and the room temperature should be recorded during the test. The standard value of conductance current is the value when the temperature is 20°C. When the difference between the test temperature and the standard temperature exceeds 5°C, it should be converted to the value at 20°C. The temperature conversion formula is

I ₂₀ ＝IT[I+K(20-T)/10]＝ITK _t

, where I ₂₀ is the conductance current converted to 20°C; T is the measured room temperature during measurement; K is the percentage change of the conductance current when the temperature changes by 10°C, generally K=0.05; K _t is the temperature of the conductance current conversion factor;

S6: Power frequency discharge voltage measurement: adjust the single-phase auto-coupling voltage regulator AV to increase the voltage evenly, and the boosting speed is controlled from the beginning of boosting to 4-5s when the arrester discharge contactor trips. The waveform of the test voltage adopts Sine wave, repeat the power frequency discharge test for each arrester 3 times, the interval between each test should not be less than one minute, take the average value of the power frequency discharge voltage of the three tests, cut off the power supply within 0.5s after the gap discharge, and install an overvoltage protection circuit in the circuit The flow rate breaks the protection device and limits the power frequency current passing through the arrester within the range of 0.2-0.7A.

Preferably, in the step S4, a shielded wire is used to connect the microammeter and the arrester.

Preferably, in the step S4, the filter capacitor with a capacitance above 0.1nF can be replaced by a phase shift capacitor.

Preferably, there are two methods for boosting the voltage of the single-phase autovoltage regulator in S6: one is manual operation, equipped with a time control device, that is, an insulating rod is fixed on the handle of the single-phase autovoltage regulator , when the voltage rises to close to the arc-extinguishing voltage, it rotates rapidly until the arrester discharges and trips; the second is electric operation, that is, a motor is used to operate the voltage regulator through the transmission device to boost the voltage, and after the arrester is discharged, the over-current trips.

Beneficial effect:

The invention provides a test method for a substation lightning arrester, which is suitable for FZ series valve type lightning arresters, eliminates potential safety hazards of the lightning arresters through experimental steps, and improves the inspection accuracy of the lightning arresters.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic diagram of measuring conductance current wiring;

Figure 2 is a schematic diagram of measuring power frequency discharge voltage wiring.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all Example. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Example 1:

As shown in Figure 1 and Figure 2, a test method for a substation lightning arrester includes the following steps:

S1 Clean the surface of the arrester, check whether there is any trauma, and whether the two ends are loose and rusted;

S2 mainly checks the sealing condition of the arrester, checks the moisture inside the arrester, the cracks of the porcelain sleeve, and checks whether the parallel resistance is in good contact, whether it is aged, deteriorated and broken;

S3 Insulation resistance test: When the interior of the arrester is damp, the insulation resistance drops significantly, the standard is ≥2000MΩ, the insulation resistance bin is not clearly specified, and can only be compared with the previous value. When measuring the insulation, use a 5000V insulation resistance meter to measure it. For multi-component components The lightning arrester should measure the insulation resistance value of each component separately to the ground;

S4 Measure conductance current: Mainly check the aging of parallel resistors. If the contact is poor, the conductance current will drop significantly. If it is broken, the conductance current will drop to zero. If it is damp, the conductance current will increase sharply to more than 1000μA. Use the half-wave rectification method to pass through the voltage regulator. The voltage regulating transformer is boosted to obtain AC high voltage, and then through the rectifier element, it becomes DC high voltage and added to the side of the arrester to be tested, and the conductance current is measured by a milliampere meter close to the high voltage side of the arrester, and a capacitance of 0.1nF is added to the high voltage rectification circuit For the filter capacitor above, use an electrostatic voltmeter to measure the DC test voltage in the rectification circuit; as shown in Figure 2, PA1, PA2, PA3: ammeter; AV: voltage regulator; T: test transformer; V: high voltage silicon stack; R1 : Protection resistor; PV1: Low-voltage side voltmeter; PV2: Electrostatic voltmeter for direct measurement of test voltage; C: Filter capacitor; F: Lightning arrester, due to the non-linearity of the parallel resistance, the pulsation of the applied high-voltage rectified voltage affects the measurement results It is relatively large, and generally requires that the voltage ripple does not exceed ±1.5%, so in the high-voltage rectification circuit, a filter capacitor with a capacity of more than 0.1nF should be added. If there is no suitable capacitor, it can be replaced by a phase-shifting capacitor. At this time, the capacitor can be used in the DC high-voltage circuit according to 3 times its AC rated voltage. The test voltage should be measured directly on the high voltage side to ensure the reliability of the test results. An electrostatic voltmeter is often used to directly measure the DC test voltage, and a high-resistance series ammeter (or a resistor divider connected to a voltmeter) can also be used for measurement. Attention should be paid to the calibration of the measurement system so that the measurement error is not greater than 2%. In the measurement of conductance current, the influence of corona current and other stray currents of equipment such as wires should be avoided as much as possible. If the ground terminal of the arrester can be disconnected, the ammeter is at the ground terminal of the arrester, that is, the position 2 in Figure 1; if the ground terminal of the arrester cannot be disconnected, the ammeter is connected to the position 1 in Figure 1, and the lead wire from the ammeter to the arrester Shielding is required, safety should be paid attention to when reading, and the accuracy of the ammeter should be greater than 1.5.

S5 Temperature conversion of conductance current: The conductance current is related to temperature, and the room temperature should be recorded during the test. The standard value of conductance current is the value when the temperature is 20°C. When the difference between the test temperature and the standard temperature exceeds 5°C, it should be converted to the value at 20°C. The temperature conversion formula is

I ₂₀ ＝IT[I+K(20-T)/10]＝ITK _t

, where I ₂₀ is the conductance current converted to 20°C; T is the measured room temperature during measurement; K is the percentage change of the conductance current when the temperature changes by 10°C, generally K=0.05; K _t is the temperature of the conductance current Conversion factor, under the specified test voltage, the conductance current value of the valve-type surge arrester with parallel resistance should be within a certain range. If the conductance current increases significantly, it means that there is moisture inside; if the conductance current decreases significantly, it is the parallel resistance. Fracture or open welding;

S6: Power frequency discharge voltage measurement: adjust the single-phase auto-coupling voltage regulator AV to increase the voltage evenly, and the boosting speed is controlled from the beginning of boosting to 4-5s when the arrester discharge contactor trips. The waveform of the test voltage adopts Sine wave, repeat the power frequency discharge test for each arrester 3 times, the interval between each test should not be less than one minute, take the average value of the power frequency discharge voltage of the three tests, cut off the power supply within 0.5s after the gap discharge, and install an overvoltage protection circuit in the circuit Flow rate cut-off protection device, and limit the power frequency current passing through the arrester within the range of 0.2-0.7A. By measuring the power frequency discharge voltage of the valve-type arrester, it can reflect whether the structure and characteristics of the spark gap are normal, and check whether the protection performance is normal. normal. The power frequency discharge voltage cannot be too high, otherwise it means that the surge voltage of the arrester is too high (because the shock coefficient of the arrester is certain). In this way, when the atmospheric overvoltage strikes, the arrester cannot operate reliably, which affects the protection performance of the arrester. Therefore, the upper limit value of the power frequency discharge voltage is stipulated in the test procedures, and the power frequency discharge voltage value must not exceed the upper limit value. At the same time, the power frequency discharge voltage should not be too low, otherwise the arc extinguishing voltage will also decrease, so that in some cases the power frequency continuous current cannot be cut off, and even the arrester may explode. In addition, misoperation may occur under internal overvoltage (the flow capacity of ordinary valve arresters is small, and it is generally not allowed to operate under internal overvoltage). Therefore, the lower limit value of the power frequency discharge voltage is stipulated in the test procedure, and the power frequency discharge voltage value must not be lower than the lower limit value.

In the step S4, a shielded wire is used to connect the microammeter and the arrester, and a shielded wire is used between the microammeter and the arrester, so that the measurement results are less affected by stray currents and the accuracy is improved; in the step S4, the electric The filter capacitor with a capacity above 0.1nF can be replaced by a phase-shifting capacitor. There are two ways to boost the voltage of the single-phase auto-transformer in the S6: one is manual operation, equipped with a time control device, that is, in the single-phase auto-transformer An insulating rod is fixed on the turning handle of the voltage regulator. When the voltage rises to close to the arc-extinguishing voltage, it rotates rapidly until the arrester discharges and trips; After discharge, the overcurrent trips.

The invention provides a test method for a substation lightning arrester, which is suitable for FZ series valve type lightning arresters, eliminates potential safety hazards of the lightning arresters through experimental steps, and improves the inspection accuracy of the lightning arresters.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be described in the foregoing embodiments Modifications are made to the recorded technical solutions, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (4)

1. a transformer substation arrester test method, is characterized in that, comprises the steps:

S1 is clean by lightning arrester surface cleaning, and check with or without wound, two ends has non-loosening and corrosion;

Whether S2 checks lightning arrester internal wetted, insulator cracks, and checks that whether the contact of parallel resistance is good, aged deterioration and fracture;

S3 megger test: measure with 5000V insulation resistance meter when measuring insulation, for the lightning arrester of multicomponent composition, tackles its insulating resistance value over the ground of each element independent measurement;

S4 measures conduction current: adopt half-wave rectification method, ac high-voltage is obtained by the boosting of pressure regulator adjustable transformer, become high direct voltage by rectifier cell again and be added in lightning arrester side to be measured, utilize milliammeter near the high-pressure side of lightning arrester to measure conduction current, in high-voltage rectifying loop, add the filter capacitor of electric capacity at more than 0.1nF, adopt the DC experiment voltage in electrostatic voltmeter measurement commutating circuit;

The temperature conversion of S5 conduction current: conduction current is relevant with temperature, should record room temperature during test.The numerical value that the standard of conduction current is temperature when being 20 DEG C, when temperature and standard temperature differ by more than 5 DEG C when tested, numerical value when should be scaled to 20 DEG C, its temperature conversion formula is

I ₂₀＝IT[I+K(20-T)/10]＝ITK _t，

I in formula ₂₀conduction current during for being converted to 20 DEG C; Actual measurement room temperature when T is measurement; K is the percentage of temperature conduction current change when often changing 10 DEG C, generally gets K=0.05; K _tfor the temperature conversion factor of conduction current;

S6: power-frequency sparkover voltage is measured: adjustment single-phase self-coupling pressure regulator AV even boosted voltage; it is 4 ~ 5s that the rate of rise controls when boosting to lightning arrester discharge contactor and thread off from just; the waveform of trial voltage adopts sinusoidal wave; each lightning arrester repeats 3 power-frequency discharge tests; each intertrial interval must not be less than one minute; power-frequency sparkover voltage gets the mean value of three tests; 0.5s internal cutting off power supply after gap discharge; install instantaneous over-current protective device in the loop, and made to be limited within 0.2 ~ 0.7A scope by the power current of lightning arrester.

2. transformer substation arrester test method as claimed in claim 1, is characterized in that, adopt shielded conductor to be connected in described step S4 between microampere meter with lightning arrester.

3. transformer substation arrester test method as claimed in claim 1, it is characterized in that, in described step S4, electric capacity can replace with phase-shift capacitor at the filter capacitor of more than 0.1nF.

4. transformer substation arrester test method as claimed in claim 1, it is characterized in that, in described S6, the method for single-phase self-coupling pressure regulator boosting has two kinds: one to be manual operation, is furnished with time-controlling arrangement, namely on single-phase self-coupling pressure regulator handle, an insulation rod is fixed, when voltage rises to close to extinguishing voltage, rotate rapidly, until lightning arrester discharge tripping operation; Two is electric operatings, is namely boosted by actuator operation pressure regulator with a motor, after lightning arrester discharge, and overcurrent trip.