GB/T 3984.1-2004 Power capacitors for induction heating devices Part 1: General
Some standard content:
GB/T3984 "Power capacitors for induction heating devices" is divided into two parts: Part 1: General principles; Part 2: Aging test, destruction test and internal fuse isolation requirements. GB/T3984.1-2004/IEC60110-1:1998 This part is the first part of GB/T3984. This standard is equivalent to IEC60110-1:1998 "Power capacitors for induction heating devices Part 1: General principles".
The main differences between this part and JB7110-1993 "Electrothermal Capacitors" are: a) The applicable frequency is changed from 40Hz to 24000Hz to 50kHz and below; b) The original standard only has water-cooled and air-cooled capacitors, and this part adds the requirements and corresponding regulations for forced ventilation capacitors;
This part adds the requirements for short-circuit discharge test, cooling pipe sealing test, and self-healing test (for capacitors with self-healing dielectric); c)
d) The AC inter-pole electrical strength test is changed from the original 2.15U for 10s to 2.0Un for 10s. The DC inter-pole electrical strength test is changed from the original 4.3UN for 10s to 4.0UN for 10s; e) The pole-to-shell withstand voltage test is also changed from the original three levels to 2.15Um, with a minimum value of 2000V and a duration of 10s. Appendix A of this part is a normative appendix, and Appendix B and Appendix C are informative appendices. This part is proposed by China Electrical Equipment Industry Association. This part is under the jurisdiction of the National Power Capacitor Standardization Technical Committee (CSBTS/TC45). The drafting units of this part are Xi'an Power Capacitor Research Institute and Shangyu Power Capacitor Co., Ltd. The main drafters of this part are Guo Tianxing and Chen Baifu. The previous versions of the standards replaced by this part are: -JB 732-1965, JB 732--1975, GB 3984-1983, JB 7110-1993. Ⅲ
1 Overview
1.1 Scope
GB/T 3984. 1—2004/IEC 60110-1: 1998 Power capacitors for induction heating devices
Part 1: General
This part of GB/T3984 applies to indoor capacitor units and indoor capacitor banks specially used to improve the power factor of induction heating, melting, stirring or casting devices, and similar applications in controllable or adjustable AC voltage systems with a nominal voltage not exceeding 3.6 kV and a frequency of 50 kHz or less.
Additional requirements for capacitors protected by internal component fuses are given in GB/T3984.2. This standard does not apply to the following capacitors:
--Series capacitors for power systems;
--Capacitors for motors and the like; -Coupling capacitors and capacitive voltage dividers;
--Self-healing shunt capacitors for AC power systems with a nominal voltage of 1 kV and below; --Shunt capacitors for AC power systems with a nominal voltage of more than 1 kV; --Non-self-healing shunt capacitors for AC power systems with a nominal voltage of 1 kV and below; --Small AC capacitors for fluorescent lamps and discharge lamps; --Capacitors for power electronic circuits;
--Capacitors for microwave ovens;
--Capacitors for suppressing radio interference;
--Capacitors intended for use under AC voltage superimposed with DC voltage. Accessories, such as insulators, switches, instrument transformers, external fuses, etc., shall comply with the corresponding national standards. The purpose of this section is:
a) to describe uniform rules for performance, testing and rating; b) to describe special safety rules;
c) to provide installation and use guidelines.
1.2 Normative references
The clauses in the following documents become clauses of this part through reference in this part of GB/T 3984. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this part. However, parties to an agreement based on this part are encouraged to investigate whether the latest versions of these documents can be used. For any undated referenced document, the latest version applies to this part. GB/T 2900.16 Electrical terminology: Power capacitors (GB/T 2900.16-1996, neqIEC 60050 (436): 1990) GB/T 3984.2 Power capacitors for induction heating devices Part 2: Aging test, destruction test and internal fuse isolation requirements (GB/T 3984.2-2004, IEC 60110-2:2000,IDT)GB/T6115 (all parts)Series capacitors for power systems (eqvIEC60143 (all parts))Self-healing shunt capacitors for AC power systems with nominal voltage up to and including 1 kVGB/T12747 (all parts)
(IEC60831 (all parts),IDT)GB/T11024 (all parts)Shunt capacitors for AC power systems with nominal voltage above 1 kV (eqvIEC60871 (all parts)
GB/T17886 (all parts)
Non-self-healing shunt capacitors for AC power systems with nominal voltage up to and including 1 kV1
GB/T 3984. 12004/IEC 60110-1: 1998 (idtIEC60931 (all parts))
JB/T8957 Method for testing the accuracy of capacitor loss tangent measurement (JB/T8957-1999, idtIEC60996:1989) 1.3 Definitions
This section adopts the following definitions:
(capacitor) element
(capacitor) element
A component mainly composed of a dielectric and two electrodes separated by it. 1.3.2
(capacitor) unit
(capacitor) unit
An assembly composed of one or more capacitor elements assembled in the same housing and with the terminals led out. 1.3.3
self-healing capacitor
Self-healing capacitor
A capacitor that can quickly and substantially recover its electrical properties after a local breakdown of the dielectric. 1.3.4
(capacitor) bank A number of capacitor units connected to act together. 1.3.5
capacitor
In this standard, the term capacitor is used when there is no need to emphasize the different meanings of a capacitor unit or a capacitor bank. 1.3.6
fcapacitor installation
capacitor installation
One or more capacitor banks and their accessories. 1.3.7
discharge device (of a capacitor) discharge device (of a capacitor) A device that can be installed inside a capacitor and can reduce the voltage between the capacitor terminals to almost zero within a given time when the capacitor is disconnected from the power supply.
Internal fuse (of a capacitor) Internal fuse (of a capacitor) A fuse connected in series with one or a group of components inside a capacitor unit. 1.3.9
Overpressure device (of a capacitor) Overpressure device (of a capacitor) A device that gives an alarm or cuts off the capacitor when the pressure inside the capacitor increases abnormally. 1.3.10
Overtemperature device (of a capacitor) Overtemperature device (of a capacitor) A device that gives an alarm or cuts off the capacitor when the temperature inside the capacitor increases abnormally. 1.3.11
Line terminal line terminal
Terminal connected to the line.
Rated capacitance (of a capacitor) (Cn) rated capacitance (of a capacitor) (C) Capacitance value used in designing a capacitor.
Rated capacity (of a capacitor) (Q~) rated output (of a capacitor) (Q~) 2
Reactive power obtained from rated capacitance, rated frequency and rated voltage. 1.3.14
GB/T 3984. 1—2004/IEC 60110-1: 1998 Rated voltage (of a capacitor) (U) rated voltage (of a capacitor) (Un) The root mean square value of the sinusoidal AC voltage used in the design of capacitors. 1.3.15
Rated frequency (of a capacitor) (fn) rated frequency (of a capacitor) (f) The frequency used when designing a capacitor.
Note: If the capacitor is intended to be used in a frequency range, fN refers to the maximum frequency in the range. 1. 3. 16
Rated current (of a capacitor) (I~) rated current (of a capacitor) (In) The root mean square value of the sinusoidal alternating current used when designing a capacitor. 1.3.17
Capacitor losses
capacitor losses
The active power consumed by the capacitor.
Note: The losses caused by all components should be included, for example: - For units, it refers to the losses caused by dielectrics, internal fuses, internal discharge resistors, connectors, etc.; - For capacitor banks, it refers to the losses caused by units, external fuses, busbars, discharge resistors, etc. 1.3.18
Tand of the loss angle (of a capacitor) (tand)The ratio of the equivalent series resistance of a capacitor to its capacitive reactance at specified sinusoidal AC voltage and frequency. 1.3.19
Maximum permissible AC voltage (of a capacitor) (Umx)Maximum permissible AC voltage (of a capacitor) (Umax)The maximum RMS value of the AC voltage that a capacitor can withstand for a given time under specified conditions. 1.3.20
Maximum permissible AC current (of a capacitor) (Imax)The maximum RMS value of the AC current that a capacitor can withstand for a given time under specified conditions. 1.3.21
Ambient air temperature
Ambient air temperature
The air temperature where the capacitor is to be installed.
Cooling air temperature
cooling air temperature
The cooling air temperature measured between the two units in the hottest area of the capacitor bank under steady-state conditions. If there is only one unit, it is the temperature measured at a distance of approximately 0.1m from the capacitor casing and 2/3 of the height from the bottom. 1.3.23
steady-state conditionsteady-state conditionThe thermal equilibrium state reached by the capacitor under constant output and constant cooling conditions. 1.3.24
residual voltage
residual voltage
The voltage remaining between the capacitor terminals after the power supply is disconnected for a given time. 1.3.25
highest voltage for equipment (Um)highest voltage for equipment (U.)The root mean square value of the sinusoidal voltage to be borne on the insulation between the terminals connected together and the casing used in the design. Note: For further details, see 6.8.
GB/T 3984. 1—2004/IEC 60110-1:19981.3.26
air temperature around water-cooled capacitorsair temperature measured 0.05m above the hottest point of the capacitor when the capacitor is in operation. 1.3.27
outlet air temperature for forced-ventilated capacitorsthe cooling air temperature leaving the capacitor measured at the hottest point. 1.3.28
inlet air temperature for forced-ventilated capacitorsthe cooling air temperature measured in the middle of the inlet air channel, where it is not affected by the heat dissipation of the capacitor. 1.3.29
container temperature rise for air-cooled capacitorsthe difference between the hottest point temperature of the case and the cooling air temperature. 1.4 Conditions of use
1.4.1 Normal conditions of use
The requirements given in this section apply to capacitors used under the following conditions. 1.4.1.1 Residual voltage when power is turned on again
The residual voltage shall not exceed 10% of the rated voltage (see 1.3.14). 1.4.1.2 Altitude
The altitude shall not exceed 1000m.
1.4.1.3 Temperature categories
Capacitors are classified according to temperature categories. Each category is represented by the lowest temperature at which the capacitor can be put into operation (selected from the three values of -25°C, -10°C, and 0°C) and the upper temperature limit of the cooling medium selected from the table below. 1 Cooling medium upper limit temperature
Unlimited maximum temperature of cooling medium/℃ Cooling type
AN Air cooling
Natural ventilation
AF Air cooling
Forced ventilation
WF Water cooling
Cooling air temperature
Unless otherwise agreed, the cooling method is selected by the capacitor manufacturer. 1.4.2 Abnormal use conditions
Cooling medium outlet temperature
Air temperature around the capacitor
This standard does not apply to capacitors whose use conditions do not meet the requirements of this standard, unless otherwise agreed between the manufacturer and the purchaser. 2 Quality requirements and tests
2.1 Test requirements
2.1.1 Overview
This clause gives the test requirements for capacitor units and, when specified, capacitor elements. Post insulators, switches, instrument transformers, external fuses, etc. should comply with the corresponding national standards. 4
2. 1. 2 Test conditions
GB/T3984.1-2004/IEC60110-1:1998 Unless otherwise specified for special tests or measurements, the temperature of the capacitor dielectric should be within the range of +5℃ to +35℃. When calibration is necessary, the reference temperature used is +20℃, except when otherwise agreed between the manufacturer and the purchaser. If the capacitor is placed in a constant ambient air temperature for an appropriate period of time without power, the dielectric temperature of the capacitor unit is considered to be the same as the ambient temperature. Unless otherwise specified, AC tests and measurements should be carried out at a frequency of 50Hz or 60Hz, regardless of the rated frequency of the capacitor. 2.2 Test classification
2.2.1 Factory tests
a) Capacitance measurement (see 2.3);
b) Capacitor loss tangent (tano) measurement (see 2.4); Terminal voltage test (see 2.5);
Terminal and housing voltage test (see 2.6.1), e)
Internal discharge device test (if any) (see 2.7); f)
Sealing test (see 2.8);
Cooling pipe sealing test (if any) (see 2.12.1). g)
The order of tests is not necessarily in the above order.
Factory tests shall be carried out by the manufacturer on each capacitor before delivery. If the purchaser so requests, the manufacturer shall provide a certificate detailing the results of these tests.
2.2.2 Type test
a) Thermal stability test (see 2.9);
Capacitor loss test (see 2.10);
c) Measurement of capacitance variation with temperature (if required) (see 2.11); Voltage test between terminal and housing (see 2.6);
Self-healing test of self-healing metallized dielectric capacitor (see 2.13);
Short-circuit discharge test (see 2.14);
Aging test (see GB/T3984.2);
Destruction test (see GB/T3984.2);
i) Internal fuse isolation test (if any) (GB/T3984.2);j) Cooling pipe sealing test (if any) (see 2.12.2). Type tests are conducted to ensure that the capacitor units meet the performance and operating requirements specified in this standard. Type tests should be conducted on capacitors of the same design as the supplied capacitors, or on capacitors that have no difference in design and process from the supplied products that may affect the various properties to be tested in the type tests. All type test items do not need to be conducted on the same capacitor unit, and can be conducted on different units with the same characteristics. The type tests listed above do not specify any test order. Unless otherwise specified, each capacitor sample intended for type testing should first pass all factory tests satisfactorily. 2.2.3 Acceptance test
Factory test and (or) type test, or some of the test items therein, may be conducted by the manufacturer in accordance with the contract signed with the purchaser and with the purchaser's consent.
The types of tests, the number of samples to be tested, the acceptance criteria and the test reports shall be determined by the manufacturer and the purchaser and shall be stated in the contract.
2.3 Capacitance measurement
2.3.1 Measurement procedure
Capacitance measurement shall be carried out at a power frequency voltage of 0.9 to 1.1 times the rated voltage (see 2.1.2) using a method that eliminates errors caused by harmonics or external accessories of the capacitor being measured. For example, errors caused by reactors and blocking circuits in the measuring circuit shall be eliminated. 5
GB/T3984.1—2004/IEC60110-1:1998 Other measurement conditions may be determined by negotiation between the manufacturer and the purchaser, for example, when the capacitor exceeds the permissible power of the bridge at rated voltage, a low voltage bridge is used. The accuracy of the measurement method and its relationship to the measured value at rated voltage and frequency shall be given. Capacitance measurement shall be carried out after the terminal voltage test (see 2.5). 2.3.2 Capacitance deviation
Deviation refers to the deviation of the capacitance value measured under the conditions of 2.3.1. The difference between the capacitance at the reference temperature (see 2.1.2) and the rated capacitance shall not exceed 5% to +10% for units or capacitor banks with 4 or fewer units, and 0 to +10% for capacitor banks with 5 or more units; the sum of the individual capacitances of a multi-terminal capacitor unit shall be within the tolerance specified for the capacitor unit. 2.4 Measurement of loss tangent (tano) of capacitors The loss tangent (tand) shall be measured at a power frequency voltage of 0.9 to 1.1 times the rated voltage (see 2.1.2) using a method that eliminates errors caused by harmonics or external accessories of the capacitor under test, such as reactors and blocking circuits in the measurement circuit. Other measurement conditions may be determined by agreement between the manufacturer and the purchaser. The measurement shall be made after the terminal voltage test (see 2.5). NOTE 1: When measuring a large number of small capacitors, the tangent may be measured by statistical sampling. The statistical sampling plan shall be determined by agreement between the manufacturer and the purchaser. NOTE 2: The tano value for some types of dielectrics is a function of the time the current is applied before the measurement. The manufacturer and the purchaser shall agree on the test voltage and power-on time. Note 3: The measuring equipment shall be calibrated in accordance with JB/T8957 or other methods that can give the same or higher accuracy. 2.5 Terminal voltage test (factory test) Each capacitor shall be subjected to the test of 2.5.1 or the test of 2.5.2. In the absence of agreement, the manufacturer shall choose. Self-healing capacitors shall be tested in accordance with 2.5.1. No breakdown or flashover shall occur during the test. For self-healing capacitors, self-healing breakdown may occur.
2.5.1 AC test
The AC test shall be carried out with an actual sinusoidal voltage of 2.0U~ and power frequency for a duration of 10s. For capacitors composed of multiple parts with a common terminal, each part shall be tested separately. For capacitors with internal series connections, no internal component breakdown and an internal fuse operation are allowed. This can be verified by the capacitance prediction when the test voltage is reduced to no more than 0.15U. The reproducibility of the measurement method should be able to detect the breakdown of a component or the operation of a fuse.
Note: If no more than two fuses are operated in each unit and there is no series connection inside the capacitor, and the capacitance deviation still meets the requirements, the operation of the internal component fuse is allowed.
2.5.2 DC test
The DC test voltage should be 4.0Un and the duration should be 10s. Note: See the note to 2.5.1.
2.6 Voltage test between terminals and shell
2.6.1 Factory test
Capacitor units with all terminals insulated from the shell should be subjected to an AC voltage test of 2.15U. (see 1.3.25) with a minimum value of 2000V at the power frequency (see 2.1.2) for 10s. The AC voltage is applied between the connected terminals and the shell. No breakdown or flashover should occur during the test. This test should be carried out even if one terminal is intended to be connected to the shell during operation. Units with one terminal fixedly connected to the enclosure shall not be subjected to this test.
This test may be omitted when the enclosure of the unit is made of insulating material. If the capacitor has several separate parts, the insulation between the separate parts shall be tested with the same test voltage and requirements as the terminal to enclosure test.
2.6.2 Type test
GB/T 3984. 1-2004/1EC 60110-1:1998 Units with all terminals insulated from the enclosure shall be subjected to the test according to 2.6.1 for a duration of 60 s. If the capacitor enclosure is made of insulating material, the test voltage shall be applied between the terminals and the metal foil tightly wrapped around the surface of the enclosure.
2.7 Test of internal discharge device
If there is an internal discharge device, its resistance shall be checked by measuring the resistance or by measuring the discharge rate (see 4.2). The test method shall be selected by the manufacturer. This test shall be carried out after the voltage test in 2.5.1. 2.8 Sealing Test
The capacitor unit shall be subjected to a test which will effectively detect any leakage in its housing and bushing. The test procedure shall be specified by the manufacturer, who shall state the test method.
If the manufacturer does not specify a procedure, the following test procedure shall be used. The unpowered capacitor unit shall be heated throughout to a temperature not less than the maximum temperature of the cooling medium listed in Table 1 plus 20°C and maintained at this temperature for 2 h.
No leakage shall occur.
It is recommended to use a suitable indicator.
Note: This test may be omitted if the capacitor does not contain liquid material at the test temperature. 2.9 Thermal Stability Test
The purpose of this test is to demonstrate the thermal stability of the capacitor unit under the following conditions. 2.9.1 Cooling Conditions
2.9.1.1 Natural Ventilation Air Cooled Capacitor (AN) Throughout the test, the capacitor shall be placed in a closed box with normal cooling conditions. The cooling air temperature in the box shall be maintained at the upper limit marked on the nameplate or higher.
Throughout the test, the cooling air temperature (see 1.3.22) shall be checked with a thermometer having a thermal time constant of approximately 1 h. 2.9.1.2 Forced Ventilation Air Cooled Capacitors (AF) The capacitor shall be placed upright in a vertical ventilation duct. For capacitors with a rectangular cross section, the ventilation duct shall also have a rectangular cross section. The size of the ventilation duct shall ensure that there is sufficient clearance on each side for the cooling air to circulate. Unless otherwise specified by the manufacturer, a clearance of 0.04 m is recommended on each side of the capacitor. The duct shall expand to approximately 0.4 m below the bottom of the capacitor housing and approximately 0.1 m above the top of the housing. The fan shall be 0.5 m to 1 m away from the duct to obtain a good uniformity of air flow rate. Preheated air shall be introduced into the duct from the bottom. The temperature of this air shall be adjusted to the upper limit of the cooling air temperature specified on the nameplate or higher, and the central air velocity between the duct wall and the capacitor shall be measured. The air temperature measurement point shall be taken just below the bottom (or above the top) of the capacitor housing. Care should be taken to ensure that the measurement is not affected by the heat radiation from the capacitor case.
The temperature of the capacitor case should be measured near the top, below the level of the impregnant (if any). The walls of the pipe should be made of insulating material.
Details of the test device are given in Appendix A.
Note: It has been calculated that the error in the temperature of the capacitor case caused by using an insulated wall pipe instead of a capacitor with the same current placed next to the capacitor under test at a distance equal to the specified gap has practically no effect on the test results. 2.9.1.3 Water-cooled capacitors (WF)
The minimum water flow rate specified on the nameplate should be maintained throughout the test. The temperature of the inlet water should be adjusted by heating so that the temperature of the outlet water remains at or above the value specified on the nameplate during the entire test. 2.9.2 Electrical conditions
The test capacity should be 1.44 times the rated capacity Q for capacitors with a rated frequency of 40 Hz to 60 Hz, and 1.44 times Qn for capacitors with a rated frequency of more than 60 Hz.33 times. 7
GB/T3984.1—2004/IEC60110-1：1998 Note: For capacitors with rated frequency of 60Hz and below, if the capacitor is selected from a batch, it is recommended to select the capacitor with the largest tano value. If the rated frequency of the capacitor cannot be achieved, the test should be carried out at a frequency as close to the rated frequency as possible, and the reactive capacity should be corrected with an appropriate correction factor according to the test frequency. The test voltage should be basically sinusoidal. 2.9.3 Test duration and criteria
The capacitor should be subjected to the cooling and electrical conditions specified in 2.9.1 and 2.9.2, and the duration should be in accordance with Table 2. At the end of the test, the loss of the capacitor or the temperature near the top of the capacitor shell should be measured at least 4 times and recorded. During the entire period, the increase in the temperature rise of the shell relative to the cooling medium should not exceed 1K. When tan can be measured, its increase should not be greater than the measurement sensitivity, and the measurement sensitivity should not be less than ±1×10-4. Table 2 Cooling and energization duration for thermal stability test Cooling type
Air cooling · Natural ventilation
Air or water ·· Forced cooling
Entire
Duration of test (minimum) of applied voltage
In hours
Capacitor in thermal equilibrium
Last test time
Note: By agreement between the manufacturer and the purchaser, the test duration may be shortened for water-cooled capacitors with a rated frequency of more than 60 Hz and a short thermal time constant.
If a large change is observed, the test shall be continued until thermal equilibrium or breakdown occurs. The capacitance measured after the test relative to the same dielectric temperature shall not differ by more than 2% from the capacitance measured before the test. If the capacitor is equipped with signaling or protection devices, these devices shall be operational during the test, but shall not operate. 2.10 Capacitor loss test
The capacitor loss shall be determined at the end of the thermal stability test after thermal equilibrium has been reached. 2.10.1 Capacitors with rated frequencies of 40 Hz to 60 Hz For capacitors with rated frequencies of 40 Hz to 60 Hz, the loss tangent (tan) shall be measured. The measuring voltage shall be the thermal stability test voltage. 2.10.2 Natural ventilation and forced ventilation air-cooled capacitors For natural ventilation and forced ventilation air-cooled capacitors with rated frequencies above 60 Hz, the loss shall be measured by the method agreed upon by the manufacturer and the purchaser. bzxz.net
2.10.3 Water-cooled capacitors with rated frequencies above 60 Hz For water-cooled capacitors with rated frequencies above 60 Hz, the loss shall be calculated by the difference between the outlet and inlet water temperatures and the water flow rate. Note 1: For water-cooled capacitors, the loss of the capacitor dissipated by the cooling water can be calculated by the following formula: P = 70 qA
tand = P/Q
Where:
P·active power, W;
water flow rate, (I./min);
A-water temperature rise, K.
Note 2: Water-cooled capacitors also dissipate some heat from the sides of the casing into the air. Therefore, if the total dissipation is to be measured, the capacitor should be enclosed in insulating material during the test. However, in most cases, it is sufficient to correct for the losses due to water dissipation using a factor derived from past experience.
2.10.4 Requirements
The values of losses (tano) measured or determined in accordance with 2.10 shall not exceed the values given by the manufacturer or agreed between the manufacturer and the purchaser. 2.11 Variation of capacitance with temperature
The variation of capacitance with temperature may be measured as a type test when there is agreement between the manufacturer and the purchaser. The capacitor shall be subjected to the electrical conditions specified in 2.3.1.
2.12 Sealing test of cooling pipes (if any) 2.12.1 Sealing test of cooling pipes, factory test GB/T 3984.1—2004/IEC 60110-1:1998 If the capacitor is equipped with cooling pipes connected to the inside of the capacitor, since the leakage cannot be detected by the capacitor unit sealing test, each cooling pipe should be subjected to a sealing test. The test method is selected by the manufacturer and should be effective in detecting leakage before the cooling pipe is installed in the capacitor.
2.12.2 Sealing test of cooling pipes, type test The manufacturer shall use a test of applying 150% of the maximum specified operating pressure to the cooling circuit for at least 5 minutes to ensure that the cooling pipes of water-cooled capacitors can withstand the water pressure that may occur in normal operation. Note: If the purchaser requires, the manufacturer shall provide the maximum difference in water pressure between the inlet and outlet at rated flow [see 5.1.2 item e)]. 2.13 Self-property test (for self-healing metallized dielectric capacitors) Self-healing capacitors shall have satisfactory self-healing properties. This may be checked by the following test. The capacitance shall be measured before and after the test in accordance with 2.3.1. The capacitor shall be subjected to the test described in 2.5.1. If less than 5 self-healing breakdowns (clearances) occur during the test period, the voltage shall be increased at a rate not exceeding 200 V/min until a total of 5 clearings have occurred since the start of the test, or until the voltage has reached a maximum value of 3.5 U. The voltage shall then be reduced to 0.8 times the voltage value at which the 5th clearing occurred, or 0.8 times the maximum voltage, and maintained for 10 s. One additional clearing is allowed to occur during this period. If there is no significant change in the capacitance measured before and after the test, the capacitor is considered to have passed the test. Self-healing breakdowns during the test may be detected by an oscilloscope, the acoustic method or the high-frequency test method. 2.14 Short-circuit discharge test
The unit shall be charged with direct current and then discharged through a gap placed as close as possible to the capacitor. The capacitor shall be subjected to 5 such discharges within 10 min.
The test voltage shall be 2UN.
The capacitance shall be measured before and after the test (see 2.3.1), and the difference between the two measured values shall be less than the amount equivalent to a component breakdown, or an internal fuse operation, or not more than 2%.
For self-healing capacitors, the capacitance change shall be less than 0.5%. And for self-healing capacitors, tano shall be measured before and after the test (see 2.4). The increase in tano after the test shall not be greater than 20%. 2.15 Aging test
See GB/T 3984.2.
2.16 Destruction test
See GB/T.3984.2.
2. 17 Internal fuse (if any) isolation test See GB/T 3984.2.
3 Overload
3.1 Maximum allowable voltage
Capacitor units are not suitable for long-term operation at a voltage between terminals exceeding the rated voltage, except during the transition process. It is allowed to operate for a maximum of 12 hours per day at a voltage not exceeding 1.05U~. The maximum value of the repeatedly applied voltage peak should not exceed 1.05×V2×U. During the transition state, the instantaneous voltage between the terminals and between the terminals and the casing should not exceed 2V2×1.05UN. 3.2 Operating voltage
Using a non-re-breakdown circuit breaker to cut off the capacitor bank usually produces a transition overvoltage with a first peak value not exceeding 2/2 times the applied voltage (effective value) and a duration of not more than 1/2 cycle. Under these conditions, about 5000 switching operations per year are acceptable, taking into account that some of them occur at temperatures below 0°C inside the capacitor, but within the temperature category (the corresponding transient overcurrent peak value may reach 100 IN (see Annex B)). Where the capacitor is switched more frequently, the amplitude and duration of the overvoltages, as well as the transient overcurrents, shall be limited to lower levels (see 6.5).
These limits and/or reductions shall be agreed between the manufacturer and the purchaser. 3.3 Maximum permissible current
Capacitor units shall be suitable for continuous operation (except transients) at the following maximum effective currents: Table 3 Maximum current permissible for continuous operation of capacitors Rated frequency N
≤60 Hz
>60 Hz
Maximum permissible current
These overcurrent factors take into account the combined effects of harmonics, overvoltages, capacitance deviations and frequency increases. 4 Safety requirements
4.1 Creepage distances
Creeppage distances and pollution levels are currently under consideration. 4.2 Discharge device
A discharge device shall be provided inside or outside the capacitor to discharge all capacitors from the initial peak voltage of /2U~ to 75V or lower within 3min.
There shall be no switch, fuse or any other isolating device between the capacitor unit and the discharge device. Note: For applications requiring a shorter discharge time, a switchable discharge resistor may be added to the safety device (see 6.5.4). Discharge devices cannot replace short-circuiting and grounding the capacitor terminals before contacting the capacitor. Note 1: Operating conditions higher than the rated voltage may cause residual voltages exceeding 75V. Note 2: It should be noted that when a shorter discharge time and a lower residual voltage are required, the purchaser should inform the manufacturer. Note 3: The discharge circuit should have a current-carrying capacity sufficient to withstand the discharge of the capacitor from the overvoltage peak specified in 3.1. 4.3 External charging connection
is only applicable to capacitors with metal casings. In order to fix the potential of the metal casing of the capacitor and withstand the fault current when the shell is broken down, the metal casing should be equipped with connections that can withstand the fault current.
4.4 Environmental protection
When the capacitor is impregnated with materials that are not allowed to diffuse into the environment, precautions must be taken. If the country has legal requirements in this regard, capacitor units and groups should be marked accordingly. 4.5 Other safety requirements
When the country where the capacitor is installed has special requirements for relevant safety regulations, the purchaser should indicate this when inquiring 5 Marking
5.1 Marking of capacitor units
5.1.1 Nameplate
The following information should be permanently marked on each capacitor unit directly or in the form of a nameplate. a) Manufacturer's name or trademark;
Identification number and year of manufacture, which can be part of the identification number or in the form of a code; 10
Rated capacity Qn, kvar, or rated capacitance Cn, μF; c
Rated voltage U, V or kV; or rated current In, A; e)
Rated frequency fn, Hz or kHz;
Cooling and temperature category
GB/T 3984.1—2004/IEC 60110-1:1998 The cooling type and temperature category shall be indicated in the following order using the symbols and values given in 1.4.1.3: 1) Cooling type;
lower limit of temperature category;
upper limit of temperature category;
4) outlet temperature of cooling medium, if used (only for forced cooling capacitors); 5) flow rate of cooling medium (only for forced cooling capacitors); for example: AN
—25/40
--25/40 outlet 4m/s
0/40 outlet 5L/min
g) Electrical components, if internal, shall be indicated by words or symbols, or by rated resistance in kilo-ohms (kQ) or megohms (MQ);
h) Internal fuses, if installed, shall be indicated by words or symbols; i)
pressure sensor isolators, if installed, shall be indicated by words or the English initials PSI; j) Maximum voltage of equipment Um, kV only for units with all terminals insulated from the casing; k) Self-healing capacity, for self-healing capacitors, shall be indicated by words "SELF-HEALING\ or "SH", or by the symbol "#"; 1) Reference GB/ 3984.1—2004;
If necessary and required, the following supplementary information shall also be given: m)
Measured capacitance value;
Superimposed DC voltage value;
Identification of the impregnating agent, if any.
5.1.2 Instructions
If the manufacturer and the purchaser reach an agreement, the following information shall be given in the instructions: Connection diagram of capacitors consisting of several parts; a "
b) Terminal marking;
If the capacitor is intended to operate at a variable frequency, the operating voltage and current limits shall be indicated (see 6.7). c)
For water-cooled capacitors , the following items should be supplemented: d) The temperature rise of the cooling water generated between the inlet and outlet of the cooling pipe of each capacitor unit when the capacitor is operating at the minimum allowable water flow and maximum allowable load;
The maximum water pressure difference between the inlet and outlet at the rated flow. 5.2 Marking of capacitor banks
The manufacturer should provide at least the following information in the manual or on the nameplate according to the purchaser's requirements: manufacturer's name or trademark;
Rated capacity Qn, kvar (give total capacity); rated voltage Un, V or kV;
c) Name
The shortest time required between cutting out and re-starting the capacitor bank; mass, kg.
6 Installation and operation guidelines
6.1 Overview
Compared with the power capacitors covered in GB/T11024, GB/T12747 and GB/T17886, the capacitor banks covered in this part 11
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