BS-9070-SECTIONS-1 2-1969.pdf
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1、BRITISH STANDARD BS 9070: Sections 1 this is defined by the temperature limits of the appropriate category 1.1.3.18 rated temperature3) the maximum temperature at which the rated voltage is applicable continuously 3) A diagram showing the relationship between the defined voltages and temperatures is
2、 given in Figure 1. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 02:28:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 9070:Sections 1 it is normally expressed in megohms 1.1.3.24 self healing a process whereby the electrical properties of a capacitor after
3、a local breakdown of its dielectric are instantaneously and essentially restored to their values before the breakdown 1.1.3.25 time constant the product of the insulation resistance and the capacitance of a capacitor, normally expressed in seconds Figure 1 Relationship between defined voltages and t
4、emperatures Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 02:28:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 9070:Sections 1 the test voltage shall be applied between the terminations connected together and the metal plate. 1.2.4.2.2 There shall be no sign
5、 of breakdown or flash-over during the test period. 1.2.4.2.3 The appropriate section of this specification prescribes: 1) the test voltage, and points of application (see Appendix A), 2) the method of applying the test voltage, either 1) or 2) of 1.2.4.2.1, 3) the duration of the test, 4) the maxim
6、um charging and discharging current, 5) when applicable, the maximum value of the time constant R1 (C1+ Cx) NOTEThe capacitor C1 may be omitted for certain types of capacitors. This should be stated in the detail specification. Figure 4 An example of a suitable test circuit Licensed Copy: London Sou
7、th Bank University, London South Bank University, Fri Dec 08 02:28:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 9070:Sections 1 b) capacitors of mass 3 g shall be mounted by insertion into a printed wiring board and soldered with the body of the capacitor pressed firmly against the surface of th
8、e printed wiring board. Alternatively, a jig giving equivalent mounting may be used. The capacitors shall be subjected to the procedure of Test Ea of BS 2011 (IEC 68-2-27) using the appropriate degree of severity as specified in the detail specification. After the test the capacitor shall be visuall
9、y examined. The measurements prescribed in the relevant section shall then be made. 1.2.6.6 Acceleration. The measurements prescribed in the relevant section shall be made. For capacitors with axial wire terminations: 1) capacitors of mass W 6 g shall be mounted by clamping the body and the terminat
10、ions; 2) capacitors of mass 6 g shall be mounted by clamping the terminations at a point 6.5 mm from the point at which they leave the body. For capacitors with radial wire terminations: a) capacitors of mass W 3 g shall be mounted by clamping the body and the terminations; b) capacitors of mass 3 g
11、 shall be mounted by insertion into a printed wiring board and soldered with the body of the capacitor pressed firmly against the surface of the printed wiring board. Alternatively, a jig giving equivalent mounting may be used. The capacitors shall be subjected to the procedure of Test Ga of BS 2011
12、 (IEC 68-2-7) using the test procedure and the appropriate degree of severity as specified in the detail specification. After the test the capacitor shall be visually examined. The measurements prescribed in the relevant section shall then be made. 1.2.6.7 Vibration. Measurements prescribed in the r
13、elevant section shall be made. For capacitors with axial wire terminations: 1) capacitors of mass W 6 g shall be mounted by clamping the body and the terminations; 2) capacitors of mass 6 g shall be mounted by clamping the terminations at a point 6.5 mm from the point at which they leave the body. F
14、or capacitors with radial wire terminations: a) capacitors of mass W 3 g shall be mounted by clamping the body and the terminations; b) capacitors of mass 3 g shall be mounted by insertion into a printed wiring board and soldered with the body of the capacitor pressed firmly against the surface of t
15、he printed wiring board. Alternatively, a jig giving equivalent mounting may be used. The capacitors shall be subjected to the procedure of Test Fc of BS 2011 (IEC 68-2-6) using Test Procedure B4 and the appropriate degree of severity as specified in the detail specification. After the test the capa
16、citor shall be visually examined. The measurements prescribed in the relevant section shall then be made. 1.2.6.8 Climatic sequence. The capacitors shall be dried as prescribed in 1.2.4.1 where specified and subjected to the following tests: 1) Initial measurements. The measurements prescribed in th
17、e relevant section shall be made. 2) Dry heat. The capacitors shall be subjected to the procedure of Test Ba of BS 2011 (IEC 68-2-2) using the degree of severity of the upper category temperature as prescribed in the detail specification for 16 h. After the specified conditioning the capacitors shal
18、l be removed from the chamber and exposed to standard atmospheric conditions for recovery for not less than 4 h. 3) Damp-heat (cyclic) first cycle. Capacitors of categories -/-/56 and -/-/21 shall be subjected to the procedure of Test Da of BS 2011 (IEC 68-24) for one cycle. Alternatively, the proce
19、dure of Test Db of BS 2011 may be used for one cycle with an upper temperature of 55 C. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 02:28:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 9070:Sections 1 f0). This is a convenient way of determining the induct
20、ance which is given by The resonant frequency as a function of capacitance and inductance is shown in Figure E.3. where = 2;f where f is the frequency of measurement Rc= effective series resistance of the capacitor Lc= inductance of the capacitor C = capacitance of the capacitor at the measuring fre
21、quency Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 02:28:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 9070:Sections 1 & 2:1969 36 BSI 03-2000 E.3 Impedance method of determination of inductance If the impedance of the capacitor is measured at a frequency
22、 above resonance such that It should be noted that this equation is true at a frequency 3.16 times the resonant frequency. At higher frequencies the coefficient 0.9 F 1. Where the resonant frequency is not known accurately at least 4 times the resonant frequency should be used and a coefficient of 0
23、.95 employed. A typical impedance/frequency characteristic is shown in Figure E.4. Hence Since Assuming that From which Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 02:28:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 9070:Sections 1 & 2:1969 BSI 03-200037
24、Figure E.1 Inductance of straight round wire, 0.2 mm diameter Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 02:28:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 9070:Sections 1 & 2:1969 38 BSI 03-2000 Figure E.2 Method of determination of impedance resonant
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