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DL 804-2014 Guidelines for the use of metal oxide surge arresters in AC power systems
Basic knowledge of lightning arresters, including operating environmental conditions, system conditions, type classification, and general selection procedures. Parameter selection during model selection and design and application, specific requirements for type test, periodic test, sampling test, acceptance test, handover test, and preventive test
Edited at 2022-10-11 11:42:34
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DL 804-2014 Guidelines for the use of metal oxide surge arresters in AC power systems
- Valentine's Day marketing campaign
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- Outline
DL 804-2014 Guidelines for the use of metal oxide surge arresters in AC power systems
3 usage environment
3.1 Normal operating conditions
3.2 Abnormal action conditions
4 Power system conditions
4.1 System nominal voltage Un
4.1 Maximum system operating voltage Um
4.2 System rated frequency 50Hz
4.3 System grounding method
Neutral point effective grounding system
The ratio of zero sequence reactance to positive sequence reactance (X0/X1) is positive and not greater than 3
The ratio of zero sequence resistance to positive sequence reactance (R0/X1) is positive and not greater than 1
Neutral point non-effective grounding system
Neutral point ungrounded method
Neutral point low resistance grounding method
Neutral point high resistance grounding method
Neutral point resonant grounding method
4.4 Ground fault factor
Neutral point effective grounding system
Bus side is not greater than 1.3
Line side is not greater than 1.4
Neutral point non-effective grounding system
Usually no greater than 1.73
When the ground resistance is 37% of the total capacitive reactance of the power grid, the ground fault factor can reach 1.82~1.90
Please refer to Appendix A for the determination method of transient overvoltage caused by ground fault.
4.5 Ground fault duration
Neutral point effective grounding system
Less than or equal to 10S
Neutral point non-effective grounding system
Not grounded, grounded through arc suppression coil, grounded through high resistance
Greater than 10S
Low resistance to ground
Less than or equal to 10S
5 Arrester Types
5.1 Classification by use
Lightning arrester for power station
Lightning arrester for power distribution
Arrester for parallel capacitors
Lightning arrester for generator
Lightning arrester for electric motor
Lightning arrester for generator neutral point
Lightning arrester for transformer neutral point
Other special purpose lightning arresters
Equipment overvoltage protection
transmission lines
Series reactor
series capacitor
Cable sheath
Current Transformer
Between voltage transformer voltage and high voltage side turns
Generator demagnetization circuit
This standard does not apply
5.2 Classification by structure
Gapless arrester
Gap arrester
5.3 Classification by jacket material
Porcelain jacket arrester
Composite jacket arrester
GIS lightning arrester
6 General procedures for arrester selection
(a~m)
7 Parameter selection and application of arrester
7.1 Continuous operating voltage Uc
The continuous operating voltage of the arrester is generally related to 75%~85% of the rated voltage.
Neutral point effective grounding system
The continuous operating voltage should not be lower than the highest operating phase voltage of the power system
Neutral point non-effective grounding system
Remove the fault within 10 seconds or less
Uc≥Um/1.732
Remove the fault after 10 seconds or more
3kV~20kV system
Uc≥1.1Um
35kV~66kV system
Uc≥Um
7.2 Rated voltage Ur
7.2.2 Neutral point effective grounding system
Usually it is equal to or greater than the maximum power frequency temporary overvoltage at the installation site.
line side
1.4 standard unit value
bus side
1.3 standard unit value
7.2.3 Neutral point non-effectively grounded system
Remove the fault within 10 seconds or less
Usually it is equal to or greater than the maximum power frequency temporary overvoltage at the installation site.
line side
1.4 standard unit value
bus side
1.3 standard unit value
Remove the fault after 10 seconds or more
Gapless arrester
Ur≥kUt
k: Time coefficient for removing single-phase ground fault
When resecting within 10S or less, k=1.0
When resection takes more than 10 seconds, k≈1.25
Ut: temporary overvoltage, kV
3~20kV system: Ut=1.1Um
35~66kV system: Ut=Um
Suggested value for Ur
Remove the fault within 10 seconds or less
System nominal voltage: 3kV
Arrester rated voltage: 4kV
System nominal voltage: 6kV
Arrester rated voltage: 8kV
System nominal voltage: 10kV
Arrester rated voltage: 13kV
System nominal voltage: 20kV
Arrester rated voltage: 26kV
System nominal voltage: 35kV
Arrester rated voltage: 42kV
System nominal voltage: 66kV
Arrester rated voltage: 72kV
Remove the fault after 10 seconds or more
System nominal voltage: 3kV
Arrester rated voltage: 5kV
System nominal voltage: 6kV
Arrester rated voltage: 10kV
System nominal voltage: 10kV
Arrester rated voltage: 17kV
System nominal voltage: 20kV
Arrester rated voltage: 34kV
System nominal voltage: 35kV
Arrester rated voltage: 51kV
System nominal voltage: 66kV
Arrester rated voltage: 90kV
7.2.4 Lightning arrester for generator protection
Suggested value for Ur
Generator rated voltage: 3.15kV
Arrester rated voltage: 4kV
Generator rated voltage: 6.3kV
Arrester rated voltage: 8kV
Generator rated voltage: 10.5kV
Arrester rated voltage: 13.5kV
Generator rated voltage: 13.8kV
Arrester rated voltage: 17.5kV
Generator rated voltage: 15.75kV
Arrester rated voltage: 20kV
Generator rated voltage: 18kV
Arrester rated voltage: 23kV
Generator rated voltage: 20kV
Arrester rated voltage: 25kV
Generator rated voltage: 22kV
Arrester rated voltage: 27.5kV
Generator rated voltage: 24kV
Arrester rated voltage: 30kV
Generator rated voltage: 26kV
Arrester rated voltage: 32.5kV
7.2.5 Lightning arrester for neutral point
Transformer neutral point arrester
When the neutral point insulation of the transformer is fully insulated, the rated voltage of the arrester
Effective grounding system: should not be lower than the highest operating phase voltage of the system
Non-effectively grounded system: should not be lower than the maximum working voltage of the system
Transformer neutral point insulation level
Fully insulated
System nominal voltage: 35kV
Arrester rated voltage: 51kV
Neutral point lightning impulse insulation level: 185kV
System nominal voltage: 66kV
Arrester rated voltage: 96kV
Neutral point lightning impulse insulation level: 325kV
Graded insulation
System nominal voltage: 110kV
Arrester rated voltage: 72kV
Neutral point lightning impulse insulation level: 250kV
System nominal voltage: 220kV
Arrester rated voltage: 144kV
Neutral point lightning impulse insulation level: 400kV
System nominal voltage: 330kV
Arrester rated voltage: 207kV
Neutral point lightning impulse insulation level: 550kV
System nominal voltage: 500kV
Arrester rated voltage: 102kV
Neutral point lightning impulse insulation level: 325kV
Generator neutral point arrester
It can be selected according to 1.25 times the rated phase voltage of the generator. suggested value:
Generator rated voltage: 3.15kV
Arrester rated voltage: 2.4kV
Generator rated voltage: 6.3kV
Arrester rated voltage: 4.8kV
Generator rated voltage: 10.5kV
Arrester rated voltage: 8.0kV
Generator rated voltage: 13.8kV
Arrester rated voltage: 10.5kV
Generator rated voltage: 15.75kV
Arrester rated voltage: 12.0kV
Generator rated voltage: 18kV
Arrester rated voltage: 13.7kV
Generator rated voltage: 20kV
Arrester rated voltage: 15.2kV
Generator rated voltage: 22kV
Arrester rated voltage: 16kV
Generator rated voltage: 24kV
Arrester rated voltage: 18.0kV
Generator rated voltage: 26kV
Arrester rated voltage: 19.0kV
7.3 Reference voltage Uref
Power frequency reference voltage
The maximum peak value of the arrester’s power frequency voltage measured under the power frequency reference current is divided by √2 (1.414)
DC reference voltage
Voltage across the arrester measured at DC reference current
7.4 Nominal discharge current
Lightning impulse current peak value with 8/20 microsecond waveform used to classify arresters.
It is related to the ability of the arrester to withstand impulse current and the protection characteristics of the arrester.
DL/T 620 regulations
66~110kV
5kA: optional
10kA: In areas with strong lightning activity, important changes
220~330kV
Optional 10~20kA
35kV and below
5kA
2.5kA
1.5kA
Near-area lightning strikes are generally not used as a basis for selecting the nominal discharge current, but the arrester should have sufficient large current impulse withstand capability
Arrester nominal discharge ammeter (Table 4)
Lightning arrester for power station
Rated voltage Ur: 414≤Ur≤828kV
Nominal discharge current In: 20kA
Rated voltage Ur: 90≤Ur≤468kV
Nominal discharge current In: 10kA
Rated voltage Ur: 5≤Ur≤108kV
Nominal discharge current In: 5kA
Lightning arrester for power distribution
Rated voltage Ur: 5≤Ur≤34kV
Nominal discharge current In: 5kA
Arrester for parallel capacitors
Rated voltage Ur: 5≤Ur≤90kV
Nominal discharge current In: 5kA
Lightning arrester for generator
Rated voltage Ur: 4≤Ur≤25kV
Nominal discharge current In: 5kA
Lightning arrester for electric motor
Rated voltage Ur: 4≤Ur≤13.5kV
Nominal discharge current In: 2.5kA
Lightning arrester for transformer neutral point
Rated voltage Ur: 60≤Ur≤207kV
Nominal discharge current In: 1.5kA
Lightning arrester for generator neutral point
Rated voltage Ur: 2.4≤Ur≤15.2kV
Nominal discharge current In: 1.5kA
7.5 Power frequency voltage withstand time characteristics
The power frequency voltage withstand time characteristics of the arrester refers to the relationship curve of the corresponding maximum duration when different power frequency voltages are applied to the arrester under specified conditions and the arrester is not damaged or thermal collapse occurs.
time limit
0.1S~20min
For neutral point non-effectively grounded systems without ground fault clearing devices, the time should be expanded to 24h
The arrester should withstand a temporary overvoltage equal to the rated voltage for 10 seconds.
If it is shorter or longer than 10S, it can be checked using the power frequency voltage withstand time characteristic curve.
7.6 Energy absorption capacity
7.6.1 Energy absorption capacity of arrester
Operational impact energy absorption capacity
The use of surge arresters for systems of 330kV and above is the main consideration
Mainly using long-duration current impulse for assessment
Lightning impact energy absorption capacity
The main consideration is the use of surge arresters for systems of 220kV and below.
Mainly using large current impact for assessment
7.6.2 Long duration current surge absorption capability
7.6.2.1 Gapless arresters shall have the ability to absorb operating impulse current energy under the following operating overvoltage
No-load line and single-phase reclosing overvoltage
Single-phase to ground fault overvoltage, transient overvoltage that occurs on a sound phase during a single-phase to ground fault
Fault clearing overvoltage, a transient overvoltage that occurs on the sound phase of the faulted line or on adjacent sound phase lines when the circuit breaker of the faulted line cuts off the fault current after a grounding or short-circuit fault on the line
Fault-free load shedding overvoltage
Oscillation decomposition overvoltage
Switching no-load transformer overvoltage
Switching parallel capacitor bank overvoltage
7.6.2.2 For different levels of arresters, the long-duration current impulse absorption capacity of the arrester can be determined through a line discharge withstand capability test or a square wave impulse current withstand capability test.
Line discharge withstand capability
Square wave impulse current withstand capability
7.6.3 Large current surge withstand capability
It is considered that when a direct lightning strike or counterattack occurs close to the installation location of the arrester, the lightning current passing through the arrester will be larger.
Nominal discharge current: 20kA
Large current surge current value (peak value): 100kA
Nominal discharge current: 10kA
Large current surge current value (peak value): 100kA
Nominal discharge current: 5kA
High current surge current value (peak value): 65kA
Nominal discharge current: 2.5kA
High current surge current value (peak value): 25kA
Nominal discharge current: 1.5kA
Large current surge current value (peak value): 10kA
7.7 Protection level and insulation coordination
7.7.2 Lightning overvoltage protection level
The maximum residual voltage under steep wave impulse current is divided by 1.15
Maximum residual voltage at nominal discharge current
Whichever is higher
7.7.3 Operating overvoltage protection levels
The wave head time of the operating impulse current for testing should not be less than 30 microseconds.
Lightning arrester for power station
Nominal discharge current In: 20kA
Rated voltage Ur: 420≤Ur≤828kV
Operating impulse current value (peak value): 500 and 2000A
Nominal discharge current In: 10kA
Rated voltage Ur: 3≤Ur≤216kV
Operating impulse current value (peak value): 125 and 500A
Nominal discharge current In: 10kA
Rated voltage Ur: 288≤Ur≤324kV
Operating impulse current value (peak value): 250 and 1000A
Nominal discharge current In: 10kA
Rated voltage Ur: 420≤Ur≤468kV
Operating impulse current value (peak value): 500 and 2000A
Nominal discharge current In: 5kA
Rated voltage Ur: 5≤Ur≤84kV
Operating impulse current value (peak value): 250A
Nominal discharge current In: 5kA
Rated voltage Ur: 90≤Ur≤108kV
Operating impulse current value (peak value): 125 and 500A
Lightning arrester for electrified railways
Nominal discharge current In: 10kA
Rated voltage Ur: 42≤Ur≤84kV
Operating impulse current value (peak value): 500A
Nominal discharge current In: 5kA
Rated voltage Ur: 42≤Ur≤84kV
Operating impulse current value (peak value): 250A
Arrester for parallel capacitors
Nominal discharge current In: 5kA
Rated voltage Ur: 5≤Ur≤90kV
Operating impulse current value (peak value): 125 and 500A
Lightning arrester for electric motor
Nominal discharge current In: 5kA
Rated voltage Ur: 4≤Ur≤25kV
Operating impulse current value (peak value): 250A
Lightning arrester for power distribution
Nominal discharge current In: 5kA
Rated voltage Ur: 5≤Ur≤17kV
Operating impulse current value (peak value): 100A
Lightning arrester for generator
Nominal discharge current In: 2.5kA
Rated voltage Ur: 4≤Ur≤13.5kV
Operating impulse current value (peak value): 100A
Lightning arrester for transformer neutral point
Nominal discharge current In: 1.5kA
Rated voltage Ur: 60≤Ur≤207kV
Operating impulse current value (peak value): 500A
Lightning arrester for generator neutral point
Nominal discharge current In: 1.5kA
Rated voltage Ur: 2.4≤Ur≤15.2kV
Operating impulse current value (peak value): 100A
7.7.4 Fit coefficient
Coordination coefficient of lightning overvoltage
Neutral point arresters and arresters close to protection equipment
Ks＞1.25
Lightning arrester non-close protection equipment
Ks＞1.4 (excluding UHV arrester)
For substations of 330 kV and above, coordination factors for substations with cable sections
If necessary, the insulation coordination status can be checked through simulation calculations.
Statistical methods can also be used to calculate the risk probability of a substation.
Cooperation coefficient for operating overvoltage
Ks＞1.15
7.8 Short-circuit current capability
In the event of an internal failure of the arrester, the fault current passing through the arrester should not cause a crushing explosion of the arrester jacket, and if an open flame occurs, it should self-extinguish within the specified time.
The short-circuit current that the arrester can withstand should be greater than the maximum short-circuit current where the arrester is installed, and the short-circuit current resistance level of the arrester should be selected accordingly.
Select short circuit current level
Please refer to the effective value of the maximum short-circuit current (periodic component) that may be achieved by system development within 10 years at the installation site.
Considering that the arrester may encounter different system short-circuit current conditions during operation, the pressure relief device of the arrester is required to operate reliably under both the rated short-circuit current and the reduced short-circuit current.
Arrester short circuit test current required value
Nominal discharge current In: 20kA, 10kA
Rated short circuit current: 80kA
Reduced short circuit current ±10%: 50kA, 25kA
Small short circuit current: 600±200
Rated short circuit current: 63kA
Reduced short circuit current ±10%: 25kA, 12kA
Small short circuit current: 600±200
Rated short circuit current: 50kA
Reduced short circuit current ±10%: 25kA, 12kA
Small short circuit current: 600±200
Rated short circuit current: 40kA
Reduced short circuit current ±10%: 25kA, 12kA
Small short circuit current: 600±200
Rated short circuit current: 31kA
Reduced short circuit current ±10%: 12kA, 6kA
Small short circuit current: 600±200
Nominal discharge current In: 20kA, 10kA, 5kA
Rated short circuit current: 20kA
Reduced short circuit current ±10%: 12kA, 6kA
Small short circuit current: 600±200
Nominal discharge current In: 10kA, 5kA
Rated short circuit current: 16kA
Reduced short circuit current ±10%: 6kA, 3kA
Small short circuit current: 600±200
Nominal discharge current In: 10kA, 5kA, 2.5kA, 1.5kA
Rated short circuit current: 5kA
Reduced short circuit current ±10%: 3kA, 1.5kA
Small short circuit current: 600±200
7.9 External insulation and minor accident resistance performance of arrester
7.10 Partial discharge and radio interference performance
Partial discharge should not exceed 10pC
7.11 Mechanical properties and seismic properties
7.12 Sealing performance
Insulating jacket arrester
Porcelain jacket arrester
Helium mass spectrometer leak detector leak detection method
The maximum seal leakage rate should be lower than 6.65*10-E5 Pa*L/S
air extraction immersion method
Put the lightning arrester into an observable sealed container containing water at ambient temperature, and pump the air pressure above the water in the container to the specified vacuum degree. If there are no continuous bubbles within the specified time, it is considered qualified.
Hot water without soaking method
Immerse the arrester in water with a specified temperature difference higher than the ambient temperature. If there are no continuous bubbles within the specified time, it is considered qualified.
Composite jacket arrester
Type test
boiling method
Immerse the arrester in a container filled with boiling deionized water for 42 hours. The NaCl content in the water is 1kg/m^3. After boiling is completed, the arrester should be kept in the container until the water has cooled to approximately 50°C and maintained at this temperature until verification tests are carried out.
Verification tests should be performed on samples that have been cooled to room temperature.
The change in DC reference voltage before and after the test is less than 5%
Leakage current changes less than 20 microamps
Partial discharge is not greater than 10pC
Routine tests
air extraction immersion method
Other effective methods
GIS lightning arrester
The relative annual leakage rate of SF6 gas from the interior of the arrester to the atmosphere should be less than 1%
7.13 Resistance to weathering and moisture infiltration
Weathering resistance
The composite jacket may be ablated or aged under the stress of long-term continuous operating voltage and humidity, heat, salt spray, strong ultraviolet rays, etc., and affect its electrical performance.
Composite jacket arresters for outdoor use should have good ability to withstand specified climatic conditions.
The ability of composite jacket arresters to withstand climate aging is related to the structural design, the specific composition of the composite material and the creepage distance.
Resistance to moisture infiltration
Composite jacketed arresters may encounter extreme high temperature or low humidity weather during operation, and may be accompanied by certain mechanical stress.
Composite jacketed arresters should undergo the moisture immersion test specified in GB11032. After the test, the arrester should not have obvious mechanical changes and have good sealing performance.
The ability of composite-jacketed arresters to withstand moisture infiltration is related to the sealing system, the high and low temperature resistance of the composite material, and the mechanical strength.
7.14 Environmental performance
The insulating jacket arrester should have the ability to withstand specified environmental conditions and ensure good sealing performance under extreme high and low temperature weather, acid rain, salt spray, etc.
specified environmental conditions
temperature cycle
The temperature difference between high and low temperature is 85K
The high temperature is not lower than 40℃ and not higher than 70℃
Sulfur dioxide with a concentration of 25*10-E6 for 21 days
Sulfur dioxide concentration 5%, lasting 96 hours
In the moisture immersion test, the composite jacketed arrester has been tested for the extreme high and low temperatures it may be exposed to, and there is no requirement for the temperature cycle test.
7.15 Discharge characteristics of gapped arrester
8 inspection
8.2 Type test
8.2.1 Gapless arrester
Porcelain jacket arrester
Table 17
Composite jacket arrester
Table 18
GIS lightning arrester
Table 19
8.2.2 Gap arrester
Table 20
DL/T 815
8.3 Periodic testing
Once every 3 years
8.3.1 Gapless arrester
8.3.1.1 Porcelain jacket arrester and GIS arrester
Table 21
8.3.1.2 Composite jacket arrester
Table 22
8.3.2 Gap arrester
Table 23
8.4 Sampling test
8.4.1 Gapless arrester
8.3.1.1 Porcelain jacket arrester and GIS arrester
Table 24
8.3.1.2 Composite jacket arrester
Table 25
8.3.2 Gap arrester
Table 26
DL/T 815
8.5 Routine testing
8.5.1 Gapless arrester
Porcelain jacket arrester
Table 27
Composite jacket arrester
Table 28
GIS lightning arrester
Table 29
8.5.2 Gap arrester
Table 30
DL/T 815
8.6 Acceptance test
Table 31
8.7 Handover test
Gapless arrester
Measure arrester and base resistance
35kV and below
Not less than 1000MΩ
2500V insulation resistance meter
35kV and above
Not less than 2500MΩ
5000V insulation resistance meter
base
Not less than 5MΩ
500V insulation resistance meter
Insulated jacket arrester
DC reference voltage
Not less than 95% of the factory value
Leakage current at 75% DC reference voltage
Not greater than 50 microamps
Measure the AC reference voltage and continuous current of the arrester
Resistive current
full current
The test results are compared horizontally, and the dispersion between them is equivalent to that of the factory test.
Check the discharge counter action indication and monitor the ammeter indication
Gap arrester
Measure arrester and base resistance
35kV and below
Not less than 1000MΩ
2500V insulation resistance meter
35kV and above
Not less than 2500MΩ
5000V insulation resistance meter
base
Not less than 5MΩ
500V insulation resistance meter
DC reference voltage
Not less than 95% of the factory value
Leakage current at 75% DC reference voltage
Not greater than 50 microamps
The measurement of gap distance should comply with the value specified by the manufacturer
8.8 Precautionary testing
DL/T 393
8.8.2 Inspection and routine testing
Inspection
project
Visual inspection
No abnormality in appearance
Porcelain sleeve without cracks
Composite jacket has no traces of electrical corrosion
No foreign matter attached
No misalignment of pressure equalizing ring
High voltage lead and ground wire are connected normally
Continuous current value
There is no abnormality in the current value
The current continuous current value should be recorded
Compare with the continuous current value of other arresters under the same operating conditions, there should be no significant difference.
counter
Record counter indication
cycle
500kV and above
2 weeks
220kV, 330kV
January
110kV, 66kV
March
Routine tests
project
Infrared thermal imaging detection
Require
No abnormality
Use an infrared thermal imaging camera to detect the arrester body and electrical connections. The infrared thermal imaging should show no abnormal temperature rise, temperature difference and/or relative temperature difference.
In case of abnormality, test the leakage current at DC 1mA voltage and 0.75U1mA.
Measurement and analysis methods refer to DL/T 664
cycle
500kV and above
1 week
220kV, 330kV
March
110kV, 66kV
half a year
Continuous current during operation
Require
When the conditions for live detection are available, this project should be carried out before the thunderstorm season every year.
Judgment is made by comparing the results of other surge arresters in the same group. There should be no significant difference between them.
The continuous running current is too large, with a DC voltage of 1mA and a leakage current of 0.75U1mA.
cycle
1 year
DC 1mA voltage and leakage current at 0.75U1mA
Require
The initial value difference of leakage current under U1mA shall not exceed 5% and shall not be lower than the value specified in GB11032 (note value)
The difference in the initial value of the leakage current at 0.75U1mA is not more than 30% or not more than 50 microamps (note value)
For single-phase multi-section series structures, this should be done section by section.
When the leakage current is too low or too high at 0.75U1mA, the influence of corona and external insulation surface leakage current should be eliminated first.
Do this project when there are defects in the resistor due to aging or internal moisture, and the hidden dangers have not been eliminated.
cycle
1 year
No continuous current detection
6 years
With continuous current detection
Base insulation resistance
Require
≥100MΩ
Measure with a 2500V insulation resistance meter
cycle
1 year
No continuous current detection
6 years
With continuous current detection
Discharge counter function check
Require
functioning normally
cycle
If there has been no inspection for more than 3 years, this project will be carried out when there is a power outage.
After checking, the current base number should be recorded
If there is an ammeter, the ammeter should be calibrated at the same time, and the calibration results should comply with the requirements of the equipment technical documents.
8.3.3 Diagnostic testing of metal oxide surge arresters
Power frequency reference voltage under power frequency reference current
Should comply with GB 11032 or manufacturer's regulations
Diagnose whether the internal resistor is aging
This project is carried out when inspecting the voltage-equalizing capacitor for defects.
For single-phase multi-series structures, this should be done section by section
Methods refer to GB 11032
The capacitance of the voltage equalizing capacitor
The initial value of the capacitance does not exceed ±5% or meets the manufacturer’s technical requirements.
If the metal oxide arrester is equipped with a voltage equalizing capacitor, this project can be carried out in order to diagnose its defects.
For single-phase multi-series structures, this should be done section by section
Diagnostic methods for metal oxide arresters in operation (Appendix B)
B.1 Arrester diagnostic device
B.1.1 Fault indicator
B.1.2 Detached products
B.1.3 Discharge counter
B.1.4 Monitoring spark gaps
B.1.5 Temperature measurement
B.1.6 Full current characteristics of metal oxide resistors
capacitive current
Resistive current
B.1.7 External surface leakage current
B.2 Measurement of full current
B.3 Measurement of resistive current
B.3.1 Measurement of fundamental wave of resistive current
B.3.2 Using voltage signals as reference
B.3.3 Balancing approach
B.3.4 Zero sequence current method
B.3.5 3rd harmonic method
B.4 Information provided by MOA manufacturer
DC 1mA (or several milliamperes) voltage value, leakage current value at 0.75 times DC 1mA (or several milliamperes) voltage, and ambient temperature, humidity, etc.
AC reference voltage value (at a reference current of several milliamperes), money current of gapless metal oxide arrester under continuous operating voltage, resistive current angle, resistive current fundamental wave peak value and ambient temperature, humidity, etc.