This standard specifies the applicable scope, terminology, product classification, technical requirements, test methods, inspection rules and markings of electric heating capacitors. JB/T 7110-1993 Electric heating capacitors JB/T7110-1993 Standard download decompression password: www.bzxz.net

Machinery Industry Standard of the People's Republic of China
710 — 93
Power Capacitor Standard
(1)
Published on October 8, 1993
Ministry of Machinery Industry of the People's Republic of China
Implementation on January 1, 1994
JB7110—93
Electrothermal Capacitors.
JB/T711493
Product Model Compilation Method of Power Capacitors.
(49)
Machinery Industry Standard of the People's Republic of China
Electrothermal Capacitors
Subject Content and Scope of Application
JB7110—93
This standard specifies the scope of application, terminology, product classification, technical requirements, test methods, inspection rules and markings of electrothermal capacitors. This standard applies to water-cooled and air-cooled electric heating capacitors (hereinafter referred to as capacitors) used to improve power factor or circuit characteristics in induction heating electrical systems with a frequency of 40 to 24000Hz. 2 Reference standards
CB311.2~311.6 High voltage test technology
GB11025
3 Terms
3.1 Capacitor
Internal fuse and internal overpressure isolator for parallel capacitorscapacitor
An assembly composed of one or more components assembled in a single housing and with terminals leading out. 3.2 Capacitor bank
capacitorbank
A group of capacitors electrically connected together. Electric heating capacitor
capacitor for electric heating installationsCapacitor used in induction heating installations. 3.4 Water-cooled capacitor for electric heating installations A type of electric heating capacitor that mainly relies on flowing water to dissipate the heat generated by losses during operation. 3.5 Air-cooled self-ventilated capacitor A type of electric heating capacitor that mainly relies on convection and radiation to dissipate the heat generated by losses during operation. 3.6 Line terminals Line terminals Used to connect to power lines or busbars. 3.7 Discharge device Discharge device A device that is connected across the line terminals or busbars of a capacitor or installed inside a capacitor. When the capacitor is disconnected from the power supply, it can reduce the residual voltage on the capacitor to a specified value within a specified time. Internal fuses Internal fuses Inside the capacitor, a fuse connected in series with a component or component group. Rated voltage (U.) ratedvoltage (U.) 3.9
The voltage (RMS value) used when designing capacitors. Rated capacitance (C,) ratedcapacitance (C,) 3.10
The capacitance used when designing capacitors. Rated frequency (f.) ratedfrequency (f.) 3.11
The frequency used when designing capacitors. 3.12 Rated current (la) ratedcurrent (l.) The current (RMS value) used when designing capacitors. 3.13 Rated capacity (Q.) ratedoutput (Q.) Approved by the Ministry of Machinery Industry on October 8, 1993
Implemented on January 1, 1994
JB7110-93
The reactive power calculated from the rated frequency, rated voltage (or rated current) and rated capacitance. 3.14 Loss ioss
Active power consumed by the capacitor.
Note: Unless otherwise specified, the loss of the capacitor should include the loss caused by the dielectric, internal fuse, internal discharge device, connectors, etc. 3.15 Tangent of the loss angle (tgo) The ratio of the loss of the capacitor to the reactive power. 3.16 Inlet water temperature inlet water temperature The temperature of the cooling water at the inlet of the capacitor cooling water pipe. 3.17 Outlet water temperature outlet water temperature The temperature of the cooling water at the outlet of the capacitor cooling water pipe. Cooling-air temperature for nir-eonled self-ventilated ea-3.18 Cooling air temperature for air-cooled capacitors
The air temperature measured at the midpoint of the line connecting the hottest points of the two capacitor shells in the hottest area of ​​the capacitor bank under steady state. If there is only one capacitor, it refers to the temperature corresponding to the hottest point of the capacitor shell, 0.1m away from the shell. 4 Product classification
Temperature category
Capacitors are classified by temperature category. Each temperature category is represented by two temperature values ​​separated by a slash. The first is the lowest temperature at which the capacitor can be put into operation, and the second is the upper limit of the cooling medium temperature. For water-cooled capacitors, the lowest temperature is not less than +5°C; the cooling medium temperature is the cooling water inlet temperature, and its value does not exceed +30°C, so the temperature category of water-cooled capacitors is: +5/+30. For air-cooled capacitors, the lowest temperature is selected from the four values ​​of +5°C, -5°C, -15°C, and -25°C; the cooling medium temperature is the cooling air temperature, and its upper limit is selected from the two values ​​of +45°C and +55°C. Any combination of the lowest temperature and the upper limit temperature can be selected as the temperature category of the capacitor.
4.2 Rated voltage
The rated voltage of the capacitor is recommended to be selected from the following values: 375, 500, 750, 1000, 1500, 2000, 3000V4.3 Rated frequency
The rated frequency of the capacitor is recommended to be selected from the following values: 50(60), 150, 400, 1000, 2500, 4000, 8000, 10000, 20000, 24000Hz. 4.4 Rated capacity
The rated capacity of the capacitor is recommended to be selected from the following values: 90, 125, 140, 160, 180, 200, 250, 280, 320, 360, 400, 500, 640800, 1000.1250, 1600, 2000, 2500, 3200kvar.
Note: Capacitors with other ratings can be manufactured according to the needs of the purchaser. 5 Technical requirements
5.1 Usage requirements
5.1.1 Altitude
The altitude of the installation and operation area should not exceed 1000m. Note: For capacitors used in areas above 1000m above sea level, the requirements are determined by the manufacturer and the purchaser. 5.1.2 Cooling medium temperature and water flow rate
For water-cooled capacitors, the inlet temperature of cooling water should not exceed +30℃; water flow rate: for 2
JB7110-93
capacitors with a rated capacity of less than 1000kvar should not be less than 4L/min; for capacitors with a rated capacity of 1000kvar and above, it should not be less than 6L/min. When the capacitor is running, the hottest air temperature measured at 5cm above the capacitor should not be higher than +50℃. For air-cooled capacitors, the cooling air temperature should not exceed the specified value in the corresponding capacitor temperature category. 5.1.3 Installation location
Capacitors should be installed indoors for use;
The installation location should be free of severe mechanical vibration; no harmful gases and vapors; no conductive or explosive dust. b.
5.1.4 Overload
5.1.4.1 Allowable overvoltage
The capacitor should be able to operate for 4 hours every 24 hours at a voltage of 1.1U. at the rated rate. In the transient state, the instantaneous voltage beep value between the terminals and between the terminals and the casing should not exceed 2√2U. . The maximum peak value of the voltage, including harmonics, should not exceed 1.6U. for capacitors with a rated frequency of 60Hz or less; and should not exceed 1.65U. for capacitors with a rated frequency of more than 60Hz. 5.1.4.2 Allowable overcurrent
The capacitor should be able to operate continuously at the following currents: not more than 1.25L for capacitors with a rated frequency of 60Hz or less. Not more than 1.351 for capacitors with a rated frequency of more than 60Hz. This current includes harmonic currents but does not include transient overcurrents. 5.1.4.3 Opening and Closing
The capacitor should be able to withstand 100 opening and closing operations without heavy breakdown every working day. 5.2 Performance and structural requirements
5.2.1 Sealing performance
The capacitor should be able to ensure that after all parts of the capacitor reach the maximum allowable operating temperature of the dielectric, it will not leak for at least 2 hours. 5.2.2 Capacitance deviation
The difference between the measured total capacitance of the capacitor under power frequency AC voltage and its rated value should not exceed -10% to +10% of the rated value. The difference between the measured value of each group capacitance of the capacitor and its rated value should not exceed -10% to +10% of the rated value. The ratio of the maximum value to the minimum value of the capacitance of each equal group of capacitors shall not be greater than 1.10. 5.2.3 Loss tangent (tg)
The loss tangent of the capacitor at 20°C under the rated voltage of industrial frequency AC shall meet the following requirements: Capacitors with rated voltage of 1kV and below:
For all-paper dielectric capacitors, it shall not be greater than 0.0040; For film-paper composite dielectric capacitors, it shall not be greater than 0.0022; For all-film dielectric capacitors, it shall not be greater than 0.0015. b. Capacitors with rated voltage above 1kV:
For film-paper composite dielectric capacitors, it shall not be greater than 0.0018; For all-film dielectric capacitors, it shall not be greater than 0.0012. Note: For capacitors with film-paper composite dielectrics, the loss tangent of different dielectric combinations shall be specified by the manufacturer under the condition that it is not greater than the corresponding specified value. The rated loss tangent of all-paper dielectric capacitors when its dielectric is at the highest operating temperature shall not exceed the above corresponding specified value. For capacitors with rated frequencies above 60Hz, the loss tangent at rated frequencies shall comply with the manufacturer's regulations. 5.2.4 Dielectric strength of dielectrics
The dielectric between the capacitor line terminals shall be able to withstand one of the following two test voltages for 10 seconds. The type of voltage to be used shall be selected by the manufacturer:
Rated AC voltage: 2.15U.
DC voltage: 4.3U.
JB7110-93
5.2.5 Insulation level
For capacitors with all line terminals insulated from the casing, the insulation between the line terminals and the casing shall be able to withstand the power frequency test voltage listed in Table 1 for 1 minute.
Rated voltage of capacitors
Rated test voltage
5.2.6 Appearance and anti-corrosion layer
The appearance of the capacitor shall comply with the requirements of the manufacturer's product drawings. Its exposed metal parts shall have a reliable anti-corrosion layer. 5.2.7 Grounding Terminal
Capacitors whose line terminals are not connected to the casing shall have terminals for grounding the casing or for fixing the potential. kv
5.2.8 Discharge Device
If a discharge device is installed inside the capacitor, the discharge device shall be able to reduce the residual voltage of the capacitor from √2U. to below 75V within the following time after the power supply is disconnected.
a. For capacitors with rated voltage of 1kV and below: 3min; b. For capacitors with rated voltage above 1kV: 10min. 5.2.9 Internal Fuse
If the capacitor is equipped with an internal fuse, when the component equipped with the fuse breaks down within the voltage range of u and u2, the fuse shall be able to disconnect the damaged component, where u; and uz are the lowest and highest instantaneous values ​​of the voltage between the capacitor terminals at the moment of fault, respectively, and the recommended values ​​of u and u2 are 0.8V2U. and 2.02U. respectively.
The fuse gap after melting must be able to withstand the steady-state voltage and positive short-term transient overvoltage that may appear on the isolated components. During the entire life of the capacitor, the fuse should be able to continuously withstand a current equal to or slightly greater than the maximum allowable value of the capacitor current divided by the number of parallel fuse paths; the inrush current caused by the switching operation and the discharge current when other internal components are damaged and the external short circuit; the fuse should be able to withstand 100 switching operations continuously per day.
6 Test methodwwW.bzxz.Net
6.1 Test conditions
All tests and measurements of capacitors, unless otherwise specified, should be carried out under the following conditions: a. The ambient air temperature is 10.5 to 10.35°C. If correction is required, it shall be based on 10.20°C. The temperature of the capacitor's dielectric should not be significantly different from the ambient air temperature. After the capacitor is placed in a constant ambient air temperature for a suitable period of time without power, the temperature of the capacitor's dielectric is considered to be the same as the ambient air temperature. b. The waveform of the AC voltage used for the test and measurement should be approximately sinusoidal (i.e. the waveforms of the two half-waves are basically the same, and the ratio of their peak value to the RMS value is within the limit of √2 ± 0.007, and the RMS value of the harmonics is not greater than 5% of the RMS value of the fundamental wave). 6.2 Appearance inspection
Carry out according to the manufacturer's drawings and relevant technical requirements. 6.3 Sealing test
The sealing test of the capacitor is carried out by heating according to the requirements of Article 5.2.1. During the factory test, an equivalent method that has been verified and proved to be effective can also be used.
6.4 Capacitance measurement
Capacitance measurement should be carried out with rated voltage. The measurement method should be able to eliminate the errors caused by harmonics and accessories in the measurement circuit. The measurement accuracy should not be less than 2%, and the measurement accuracy should be sufficient to reflect the amount of breakdown of a component. In order to reveal whether there is a capacitance change caused by a component breakdown or an internal fuse blowing, the capacitance should be initially measured at a voltage not higher than the rated voltage before other electrical tests; after the withstand voltage test, the capacitance should be re-measured at a voltage of (0.9~1.1)U. 6.5 Withstand voltage test
The withstand voltage test of capacitors is generally carried out in accordance with the relevant provisions in GB311.2~311.6. Additional instructions are as follows: a. When applying voltage, the voltage should start from half of the rated voltage of the capacitor or lower, and rise to the test value evenly within 2~10s, and maintain the required time at the test voltage. b. When conducting the withstand voltage test of the line terminal to the shell, all the line terminals insulated from the shell should be connected together, and the voltage should be applied between this common joint and the shell.
c. When testing with DC voltage, the capacitor should be discharged through a resistor with a limiting current of no more than 10In after the test. d. During the test, check whether the capacitor is damaged by following the instructions of the instrument, the discharge sound, observation and re-measurement of the capacitance. 6.6 Measurement of loss tangent (tg8)
6.6.1 Factory test
During factory test, the loss tangent of capacitors shall be measured at rated voltage of power frequency after withstand voltage test, and the measurement accuracy shall not be less than 20%.
6.6.2 Type test
6.6.2.1 For capacitors with rated frequency of 40-60Hz, after the capacitor reaches thermal stability under the conditions specified in 6.7, the measurement shall be carried out in accordance with 6.6.1.
6.6.2.2 For water-cooled capacitors with a rated frequency of more than 60 Hz, after the capacitor reaches thermal stability under the conditions specified in Article 6.7, the loss of the capacitor at the rated frequency is calculated as follows: P=70g9
Where: P-the loss of the capacitor after reaching thermal stability, W; g-the flow rate of cooling water, L/min;
△9-the temperature difference between the outlet and inlet water, K, and the capacitor loss tangent is calculated as follows: tg5=P/Q
Where: P-the loss of the capacitor calculated according to formula (1); (1)
Q-the capacity of the capacitor during the thermal stability test. Water-cooled capacitors also dissipate some heat from the side of the shell into the air. Therefore, to measure the total loss, the capacitor can be wrapped with insulating material during the test, or an empirical coefficient can be used to correct the loss dissipated by water. 6.6.2.3 For air-cooled capacitors with a rated frequency of more than 60 Hz, place all the capacitors in a water tank with a high-efficiency insulation material insulation jacket, with the water level just reaching the insulation of the outgoing wires. Water preheated to a temperature 5°C lower than the temperature reached by the capacitor shell at the end of the thermal stability test is injected from the bottom of the tank at a known rate. Measure the water temperature at the outlet of the top of the tank. Apply a test voltage of the rated frequency to the capacitor, so that the capacitor reaches and maintains 1.0Qn until the temperature difference between the inlet and outlet water stabilizes. At the same time, adjust the water flow rate so that the temperature difference does not exceed 5°C. The loss of the capacitor is calculated according to formula (1).
The loss tangent of the capacitor is calculated according to formula (2). Where Q=Q. 6.7 Thermal stability test
6.7.1 Cooling conditions
For water-cooled capacitors, the inlet water temperature is maintained at 30±3°C during the entire test process, and the water flow rate is the minimum value specified in Article 5.1.2.
For air-cooled capacitors, place the capacitor in a constant temperature box, and keep the air temperature in the box within the upper limit temperature specified in the temperature category of the tested capacitor ±2°C. The temperature should be measured using a thermometer with a thermal time constant of approximately 1h. 5
6.7.2 Electrical conditions
JB 7110-93
When all parts of the water-cooled capacitor have reached the temperature of the cooling water and all parts of the air-cooled electrocorroder have reached the temperature in the constant temperature box, apply a test voltage of rated frequency and approximately sinusoidal waveform to the capacitor, and its value is calculated according to the following formula: U=1.15UV(1.1C,/C)(f./f)
In the formula; C—rated capacitance of the capacitor, μuF; C——measured capacitance of the capacitor, uF;
f. —rated frequency of the capacitor, Hz
Test frequency, Hz;
U.—rated voltage of the capacitor, kV.
The voltage should remain constant during the entire test. 6.7.3 Test duration and criteria
The time for applying the test voltage: 12h for water-cooled capacitors; 48h for air-cooled capacitors. *(3)
During the last 6 hours of the test, the temperature of the housing near the top shall be measured at least 4 times. The temperature increase within this 6 hours shall not exceed 1K. If it exceeds, the test shall be continued until the measurement within 6 hours meets the above requirements. For water-cooled capacitors, the outlet temperature of the cooling water shall also be measured, and its value shall not exceed +40°C. The capacitors used for thermal stability tests shall be selected from the most suitable capacitors. During the test, fluctuations in voltage, frequency, cooling water temperature, flow rate and surrounding air temperature of the test sample shall be considered. For this purpose, it is recommended to make a function curve of these parameters and capacitor temperature rise or loss versus time. When required by the purchaser, a curve of the relationship between capacitor capacitance and temperature shall also be made. Before and after the test, the capacitance and power frequency loss tangent shall be measured within the standard test temperature range. The change in capacitance shall not exceed 2%. The increase in loss tangent shall be within the measurement error range. 6.8 Discharge device inspection
The discharge efficiency of the discharge device can be measured by the discharge method. If the discharge device is a resistor type, it can also be measured by measuring the resistance. Resistance at this time:
Wherein, R—resistance, MO;
t——discharge time, 3
C--capacitor capacitance, μF
U.——rated voltage of capacitor, kV; U.—allowable residual voltage, kV.
Internal fuse test
Internal fuse test is divided into: discharge test and isolation test. These two tests can be performed on one capacitor or two capacitors; isolation test can also be performed on two capacitors, which is selected by the manufacturer. When two capacitors are used for isolation test, one is tested at the upper limit voltage and the other is tested at the lower limit voltage.
6.9.1 Discharge test
Charge the capacitor to 2.5U. with direct current, and then discharge it through a gap without any external impedance in the circuit as close to the capacitor as possible. Such discharge should be completed 5 times within 10 minutes. To prove that the fuse does not act during the test, the capacitance should be measured before and after the test. 6.9.2 Isolation test
6.9.2.1 Test steps
Before the test, the capacitance should be measured first, and then a lower limit voltage of 0.8U should be applied to the capacitor. After one fuse is blown, the upper limit voltage of 2.2U should be switched as soon as possible until the other fuse is blown. JB7110-93
The test voltage applied in this test can be AC ​​or DC, which is selected by the manufacturer. If AC voltage is used, the waveform of the current should be recorded during the test to determine whether the breakdown occurs at the peak value of the AC test voltage or at the moment close to the peak value.
If DC voltage is used, the capacitor should be charged to twice the corresponding AC test voltage. In order to make the components connected in series with the fuse easy to break down, one of the methods described in A1 to A5 of Appendix A of GB11025 should be used. Note: ① During the upper limit voltage test, the number of damaged fuses connected to the intact components should not exceed one (or one tenth of the number of parallel components in the fault section). ② After the breakdown, the test voltage should be maintained for a few seconds to ensure that the fuse has indeed played an isolation role. In special occasions, it may be necessary to extend the test to two or more capacitor components to break down. The number of breakdowns at each voltage limit shall be agreed upon by the purchaser and the manufacturer. ④ In order to verify the current limiting performance of the fuse, when testing at the upper limit voltage, in addition to the transition voltage, the voltage drop across the two ends of the disconnected fuse gap shall not exceed 30%. ② If the fuse cannot meet the requirements of Note ①, it is necessary to determine whether the parallel stored energy and the rated fault current obtained from the system can represent the operating conditions, and then conduct a test to confirm whether the fuse is melted satisfactorily. It should be noted that during this test, the capacitor unit may explode and the nail may be ejected violently. 6.9.2.2 Measuring capacitance
After the test, the capacitance should be measured to confirm that the fuse has blown. The measurement method used should be sufficient to detect the change in capacitance caused by the blowing of one fuse.
6.9.2.3 Observation of capacitors
Observe the shell before opening it. There should be no significant deformation. Then open the capacitor shell for inspection. It should be seen that the intact fuse has no significant deformation.
b. The number of damaged fuses connected to the intact components shall not exceed one (or one tenth of the number of parallel components in the fault section). When the isolation test is carried out on two capacitors, the calculation is combined. Note: ① A small amount of black contamination of the diffusion agent does not affect the quality of the capacitor. ② Since the disconnected components may have dangerous residual charge due to the blown fuse or damage to their connection, all components should be protected from ground effect voltage. Withstand voltage test Withstand voltage test is to apply a DC voltage of 3.5 times the rated voltage of the component to the disconnected fuse after the shell is opened for 105 seconds. During the test, the gap should be in the impregnant and the gap should not be broken down. For capacitors with all components connected in parallel, this test can be tested with AC voltage before the shell is opened. The test voltage value is 1/V2 times the above test voltage. Inspection rules Capacitor tests are divided into: factory test, type test and acceptance test. The test items are shown in Table 2. 7.1 Factory test The purpose of the factory test is to detect defects in manufacturing. This test is carried out by the manufacturer on each capacitor produced. 7.2 Type test The purpose of the type test is to examine whether the design, materials and manufacturing of the capacitor meet the performance and use requirements specified in this standard.
Type test is carried out when new products are manufactured. In production, when there are changes in materials, processes or product structures and the changes may affect the performance of capacitors, type tests should also be carried out. At this time, only test items related to these changes are allowed. The capacitors used for type tests should be capacitors that have passed factory tests. All type tests do not necessarily have to be carried out on the same capacitor.
JB7110-93
Except for the thermal stability test, which can only take the data of one capacitor, the remaining type test items should have test data of at least two capacitors. In normal production, type tests should be carried out at least once every five years. Type tests are carried out by the manufacturer, and certificates of these test results should be provided when the purchaser requires them. Acceptance test
Acceptance test is mainly a test carried out by the purchaser before installation. The purpose of this test is to check whether the capacitor has been damaged during transportation to ensure that the installed capacitor is good. When conditions permit, the recommended test items are shown in Table 2. Table 2
Type test
Acceptance test
Test items
Appearance inspection
Sealing test
Capacitance measurement
Withstand voltage test
Loss tangent measurement
Discharge device inspection
Thermal stability test
Loss tangent measurement at rated frequency
Internal fuse test
Capacitance measurement
Withstand voltage test||tt| |Measurement of loss tangent of workpiece
Technical requirements
Each capacitor should have a nameplate indicating the following:a.
Name:
Model:
Rated frequency, kHz;
Rated voltage, kV:
Rated capacity, kvar;
Measured capacitance, μF;
Cooling type;
Temperature category;
For water-cooled capacitors, the water flow rate should also be indicated. i.
Test method
If there is an internal discharge device, it shall be indicated by the symbol "口一"; if there is an internal fuse, it shall be indicated by the symbol "一"; Capacitor serial number;
Manufacturing year and month;
Code of this standard;
For all-paper dielectric capacitors, part of the capacitor shall be extracted for dielectric loss tangent measurement at the highest allowable operating temperature. The test voltage applied shall be 75% or less of the factory test voltage
Name of the manufacturer.
Part of the content in the mark may be indicated in the manual. Safety requirements
9.1 Discharge device
JB7110-93
Each capacitor shall be equipped with a discharge device. When the capacitor is directly connected to other electrical equipment that can provide a discharge path and its circuit performance is sufficient to meet the discharge requirements, it shall be considered to have appropriate discharge capacity and it is not necessary to install a discharge device. For capacitors equipped with discharge devices, there shall be no switches, fuses or other isolation devices between the discharge device and the capacitor. When capacitors may be switched on and off at short intervals, appropriate measures should be taken to ensure that the voltage on the capacitor terminals is not greater than 10% of the rated voltage when the voltage is reapplied. When capacitors are connected in series, the discharge device installed on each capacitor may not be sufficient to meet the discharge requirements due to the cumulative effect of the residual voltage. In this case, an additional external discharge device is required and should be directly connected across each capacitor or capacitor group. Although there is a discharge device, the terminals of the capacitor should still be short-circuited and grounded before people touch it. When capacitors are connected in series, the interconnections of the connected capacitors should also be short-circuited and grounded. 9.2 Shell connection
In order to fix the potential of the metal shell of the capacitor and withstand the fault current in the event of a breakdown of the shell, the shell must be equipped with a terminal capable of withstanding the fault current.
For capacitors with a line terminal fixedly connected to the shell, the terminal should have a sufficient cross-section to ensure reliable operation and prevent overheating.
9.3 Cooling pipe
The manufacturer should ensure that the cooling pipe of the water-cooled capacitor can withstand any hydrostatic pressure that may be avoided under normal operating conditions. The cooling pipe should be tested at 0.5MPa pressure for 1min before assembly.
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