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项目名称
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章节号
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测试方法
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Capacitance
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4.5
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Constant current discharge method
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4.5.1
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a) If the d.c. voltage of the constant current/constant voltage power supply is not specified in the individual standards, set at the rated voltage (UR).
b) Set the constant current value of the constant current discharger to the discharge current specified in Table 2.
c) Turn the switch S to the d.c. power supply, and unless otherwise specified in the individual standards, apply voltage and charge for 30 min after the constant current/ constant voltage power supply has achieved the rated voltage.
d) After a charge for 30 min has finished, change over the switch S to the constant current discharger, and discharge with a constant current.
e) Unless otherwise specified in the individual standards, measure the time t1 and t2 where the voltage between capacitor terminals at the time of discharge reduces from U1 to U2 as shown in Figure 2, and calculate the capacitance value by the following formula:
f) The discharge current I and the voltages U1 and U2 at the time of discharge voltage drop shall be as per Table 2. The method classification shall be in accordance with the individual standards.
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Constant resistance charging method
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4.5.2
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a) Prior to measurement, short-circuit between capacitor terminals for 30 min or more and discharge sufficiently.
b) Measure the time constant (τ ) when the d.c. voltage of UR is applied, and calculate the capacitance value by the following formula:
c) Set the value of R so that τ becomes 60 s to 120 s.
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Internal resistance
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4.6
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AC resistance method
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4.6.1
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a) The internal resistance Ra of a capacitor shall be calculated by the following formula:
b) The frequency of the measuring voltage shall be 1 kHz.
c) The a.c. current shall be from 1 mA to 10 mA.
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DC resistance method
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4.6.2
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a) Use the measuring circuit, shown in Figure 1 in 4.5.1.1 (Constant current discharge method). If the applied voltage is not specified in the individual standards, set at the rated voltage. Use a voltage recorder to measure the voltage between capacitor terminals.
b) Turn the switch S to the d.c. power supply and unless otherwise specified in the individual standards, apply voltage and charge for 30 min after the constant current/ constant voltage power supply has achieved the rated voltage.
c) After a charge for 30 min has finished, change over the switch S to the constant current discharger. Unless otherwise specified in the individual standards, discharge with a constant current specified in Table 3.
d) Record the time-varying voltages between the capacitor terminals with a voltage recorder.
e) Draw an auxiliary line while extending the straight part of the time-varying voltages between the capacitor terminals obtained from the voltage recorder, read the voltage drop U3 obtained from the intersection of the auxiliary line and the time base at the time of discharge start shown in Figure 5, and then calculate the internal resistance Rd by the following formula.
f) The discharge current I shall be as per Table 3. The method classification shall be in accordance with the individual standards.
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Leakage current
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4.7
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a) Discharge duration.
Before this measurement is made, the capacitors shall be fully discharged. Discharge procedure shall take 1 h to 24 h and shall be specified in the relevant specification.
b) The leakage current shall be measured, unless otherwise prescribed in the relevant specification, using the direct voltage (UR) appropriate to the test temperature. Electrification period after maximum 30 min charge-up time to reach 95 % of the applied voltage shall be selected from 30 min, 1 h, 2 h, 4 h, 8 h, 12 h, 24 h or 48 h and shall be specified in the relevant specification.
c) A steady source of power such as a regulated power supply shall be used.
d) Unless otherwise specified in the relevant specification, apply the voltage to a capacitor through a protective resistor of 1 000 or less.
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Self-discharge
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4.8
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a) Before this measurement is made, the capacitors shall be fully discharged. Discharge procedure shall take 1 h to 24 h and shall be specified in the relevant specification.
b) Apply the rated voltage UR directly to the capacitor terminals, without using a protective resistor. Unless otherwise specified by the relevant specifications, charging time shall be 8 h, including maximum 30 min charge-up time to reach 95 % of the applied voltage.
c) Disconnect the capacitor terminals from the voltage source. Unless otherwise specified in the detail specification, the capacitor shall be kept under standard conditions for 16 h or 24 h.
d) The internal resistance of the d.c. voltmeter used shall have a value of at least 1 M.
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Robustness of terminations
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4.9
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Resistance to soldering heat
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4.10
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Solderability
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4.11
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Rapid change of temperature
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4.12
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4.12.1 The measurements prescribed in the relevant specification shall be made.
4.12.2 The capacitors shall be subjected to Test Na of IEC 60068-2-14, using the degree of severity as prescribed in the relevant specification.
4.12.3 After recovery, the capacitors shall be visually examined. There shall be no visible damage.
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Vibration
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4.13
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4.13.1 The measurements prescribed in the relevant specification shall be made.
4.13.2 The capacitors shall be subjected to Test Fc of IEC 60068-2-6, using the mounting method and the degree of severity prescribed in the relevant specification.
4.13.3 When specified in the detail specification, during the last 30 min of the vibration test an electrical measurement shall be made in each direction of movement to check intermittent contacts, or open- or short-circuits. The method of measurement shall be prescribed in the detail specification.
The duration of the measurement shall be the time needed for one sweep of the frequency range from one frequency extreme to the other.
4.13.4 After the test the capacitors shall be visually examined. There shall be no visible damage. When capacitors are tested as specified in 4.17.3, the requirements shall be stated in the detail specification.
4.13.5 The measurements prescribed in the relevant specification shall then be made.
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Damp heat, steady state
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4.14
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4.14.1 The measurements prescribed in the relevant specification shall be made.
4.14.2 The capacitors shall be subjected to Test Cab of IEC 60068-2-78, using the degree of severity corresponding to the detail specification.
4.14.3 The measurements prescribed in the relevant specification shall then be made.
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Endurance
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4.15
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4.15.2 The tests of IEC 60068-2-2 apply as follows:
d.c. tests – Test Ba;
The test specimens may be inserted in the oven at any temperature between room ambient temperature and the specified oven temperature, but the voltage shall not be applied to the capacitor before it has reached the oven temperature.
4.15.4 Unless otherwise specified in the relevant specification, the voltage to be applied during the test shall be selected from the following:
d.c. tests
The test shall be carried out at a multiplying factor times the rated voltage (d.c.) at temperatures up to the rated temperature. The test temperature and the value of the multiplying factor shall be specified in the relevant specification. For tests at upper category temperature the derating factor for the voltage shall be given as well.
4.15.5 The capacitors shall be placed in the test chamber in such a manner that:
a) for heat dissipating capacitors, no capacitor is within 25 mm of any other capacitor;
b) for non-heat dissipating capacitors, no capacitor is within 5 mm of any other capacitor.
4.15.6 After the specified period, the capacitors shall be allowed to cool to standard atmospheric conditions for testing and where specified in the relevant specification, the capacitors shall be subjected to recovery.
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Storage at high temperature
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4.16.1
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4.16.1.1 The measurements prescribed in the relevant specification shall be made.
4.16.1.2 The capacitors shall be subjected to Test Ba of IEC 60068-2-2, using the following severities:
– temperature: upper category temperature;
– duration: 96 h ± 4 h.
4.16.1.3 After recovery for at least 16 h, the measurements prescribed in the relevant specification shall be made.
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Storage at low temperature
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4.16.2
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4.16.2.1 The measurements prescribed in the relevant specification shall be made.
4.16.2.2 The capacitors shall be subjected to Test Ab of IEC 60068-2-1. The capacitors shall be stored at – 40 °C for either a period of 4 h after thermal stability has been reached, or for 16 h, whichever is the shorter period.
4.16.2.3 After recovery for at least 16 h, the measurements prescribed in the relevant specification shall be made.
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Characteristics at high and low temperature
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4.17
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Dry heat
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4.17.2
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The capacitors shall be subjected to Test Ba of IEC 60068-2-2 for 16 h, using the degree of severity of the upper category temperature, as prescribed in the detail specification.
While still at the specified high temperature and at the end of the period of high temperature, the measurements prescribed in the relevant specification shall be made.
After the specified conditioning, the capacitors shall be removed from the chamber and exposed to standard atmospheric conditions for testing for not less than 4 h.
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Cold
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4.17.3
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The capacitors shall be subjected to Test Aa of IEC 60068-2-1 for 2 h, using the degree of severity of the lower category temperature, as prescribed in the relevant specification.
While still at specified low temperature and at the end of the period of low temperature, the measurements prescribed in the relevant specification shall be made.
After the specified conditioning, the capacitors shall be removed from the chamber and exposed to standard atmospheric conditions for testing for not less than 4 h.
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Component solvent resistance
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4.18
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The components shall be subjected to Test XA of IEC 60068-2-45, with the following details:
a) solvent to be used: see 3.1.2 of IEC 60068-2-45;
b) solvent temperature: 23 °C ± 5 °C, unless otherwise specified in the detail specification;
c) conditioning: Method 2 (without rubbing);
d) recovery time: 48 h, unless otherwise stated in the detail specification.
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Solvent resistance of marking
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4.19
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The components shall be subjected to Test XA of IEC 60068-2-45, with the following details:
a) solvent to be used: see 3.1.2 of IEC 60068-2-45;
b) solvent temperature: 23 °C ± 5 °C;
c) conditioning: method 1 (with rubbing);
d) rubbing material: cotton wool;
e) recovery time: not applicable, unless otherwise stated in the detail specification.
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Passive flammability
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4.20
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4.20.1 The test shall be made according to IEC 60695-11-5.
4.20.2 The capacitor under test shall be held in the flame in the position which best promotes burning (if this position is not given in the detail specification it shall be evaluated by pretesting). Each specimen shall only be exposed once to the flame.
4.20.3 The smallest, a medium (in the case of more than four case sizes), and the biggest case size shall be tested. Of each case size, three specimens of the maximum and three specimens of the minimum capacitance shall be tested, resulting in six specimens per case size.
4.20.4 For time of exposure to flame and burning time, see Table 6. If applicable, the detail specification shall specify the category of passive flammability.
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