as series inrush current limiters when a battery is connected to a load with capacitive input, there is an inrush current surge as the capacitance is being charged to the battery voltage. the input current depends on the input capacitance; the larger the batteries and the more powerful the load, the larger the input capacitance. a large inrush current (in the precharge circuit, without protection) can cause the following: ? damage to input filter capacitors ? blowing of the main fuse if asked to carry the inrush current without protection ? contact failure (as well as reduction in current carrying capacity) due to arcing and pitting that results from high inrush current ? damage to the battery cell, which is not rated for inrush current a typical precharge circuitry for battery operation is below with the timing diagram, showing how the circuit operates. (courtesy of lithium -ion bms) thermistor protection for precharge circuit on lithium ion batteries + ? r1 k1 10 battery controller precharge hv out k2 b= k3 b- k1+ k1+ k1? k1+ k1+ k1? + ? the minimum resistance of the thermistor is determined by the following: 1. ambient temperature 2. input capacitance value (of the precharge circuit) 3. battery voltage the precharge surge current reaches 63.2% (1/e) of its initial value after a time = rc. in the selection of the thermistor, we consider a time value of ?five time-constant? when the capacitances are fully charged and the surge current reaches the normal operating current. for the purpose of our design, let us assume the following quantitative values: precharge time: 20 millisecond ambient operating temperature: varies between 10c to 50c. battery voltage: 100 volt capacitor bank : 50,000 f 5 = rc r = 5 / c = 5 (0.02 sec) / 0.05f = 2.0 . now, look at the at r-t curves for ametherm thermistor at ambient of 50c. the material ?c?exhibits r @ 50c/ r @ 25c = 0.412 @ r @ 10c / r @ 25c = 1.70 therefore, minimum resistance @ 25c = 2.0 / 0.454 = 4.40 , so our standard part has 5.0 ohm nominal resistance at 10c, the standard part will have a resistance of 5.0 x 1.70 = 8.50 , which will meet our minimum resistance. determine the energy the thermistor needs to handle with out self-destruction, e = ? c v2 = ? (0.05) (100) 2 = 250 joules. the steady state current is not calculated because in most precharge circuits the steady state current goes through the contactor. the part, which would meet your specification, is as32 5r020. in its most basic form, the precharge circuit operates as follows: ? off: when the system is off all relays / contactors are off. ? precharge: when the system is first turned on, k1 and k3 are turned on to precharge the load, until the inrush current has subsided. r1 shows the location of thermistor in the precharge circuit. ? on: after precharge, contactork2 is turned on (relay k1, must be off to save coil power) v precharge surge normal operating current load voltage t a battery current t off on pre charge k1 k1 k1 t off selection of the thermistor for this application note, let us limit our discussion to the selection of the thermistor
key benefits of ametherm as inrush current limiters ? lower current density (as compared to traditional types of inru sh current limiters) ? faster reset time ? no hot spots from fatigue, because of lower current density and uniform temperature gradient throughout the disc ? wider temperature range of operation with out de-rating d a l s b t c p ad l ayout y x t: 800-808-2434 775-884-2434 (outside the us and canada) f: 775-884-0670 www.ametherm.com info@ametherm.com 3111 n. deer run road carson city, nevada 89701 usa r @ 25o c ( ) m ax i ( a ) hot r ( ) m ax ener g y ( j oules ) m a x c a p @ 680vac c ool dow n tim e ( sec) r - t c u r v e d c m w / o c b ody t e m p @ m a x ssi ( o c ) 0 . 50 3 0 0 . 011 300 650 120 a 78. 2 0 199 0.50 3 6 0 . 009 300 650 120 a 78. 2 0 199 2 . 0 2 5 0 . 020 300 650 120 c 78. 2 0 220 5 . 0 2 0 0 . 027 300 650 120 g 78. 2 0 255 10. 0 1 5 0 . 052 250 500 120 h 85. 2 0 185 20. 0 1 0 0 . 0 95 250 500 120 i 58. 0 0 192 50. 0 6 0 . 380 250 540 120 m 78. 2 0 212 0 . 5 0 5 0 0 . 0074 800 1730 200 a 129. 4 4 210 1 . 0 4 0 0 . 0113 800 1730 200 b 127. 0 0 212 2 . 0 3 5 0 . 0147 700 1500 200 c 119. 2 0 210 3 . 0 3 0 0 . 0135 600 1300 200 c 116. 4 0 215 5 . 0 2 5 0 . 0288 600 1300 200 g 112. 2 208 10. 0 1 8 0 . 0556 500 1080 200 i 122. 8 0 220 20. 0 1 0 0 . 1760 500 1080 200 m 101. 1 0 177 *as32 0 r 530 *as32 0 r 536 a s32 2 r 025 a s32 5 r 020 a s32 10015 a s32 20010 a s32 50006 a s35 0 r 550 a s35 1 r 040 a s35 2 r 035 a s35 3 r 030 a s35 5 r 025 a s35 10018 a s35 20010 electrical specifications part number 1.0 3 0 0 . 013 300 650 120 b 79.40 215 1 . 0 3 6 0 . 010 300 650 120 b 79. 4 0 215 *as32 1 r 030 *as32 1 r 036 d ( mm) t ( mm) s ( mm) l ( mm) a ( mm) b ( mm) c ( mm) x ( mm) y ( mm) 30. 0 7 . 8 17. 1 22. 0 2 . 2 4 . 8 0 . 8 17. 1 4 . 8 30. 0 7 . 8 17. 1 22. 0 2 . 2 4 . 8 0 . 8 17. 1 4 . 8 30. 0 7 . 8 17. 1 22. 0 2 . 2 4 . 8 0 . 8 17. 1 4 . 8 30. 0 8 . 2 17. 1 22. 0 2 . 2 5 . 4 0 . 8 17. 1 5 . 4 30. 0 9 . 0 17. 1 22. 0 2 . 2 6 . 8 0 . 8 17. 1 6 . 8 30. 0 8 . 5 17. 1 22. 0 2 . 2 6 . 4 0 . 8 17. 1 6 . 4 30. 0 8 . 2 17. 1 22. 0 2 . 2 5 . 4 0 . 8 17. 1 5 . 4 36. 0 6 . 4 19. 0 22. 0 2 . 2 3 . 4 0 . 8 19. 0 3 . 4 36. 0 8 . 5 19. 0 22. 0 2 . 2 5 . 5 0 . 8 19. 0 5 . 5 36. 0 8 . 5 19. 0 22. 0 2 . 2 5 . 5 0 . 8 19. 0 5 . 5 36. 0 8 . 5 19. 0 22. 0 2 . 2 5 . 5 0 . 8 19. 0 5 . 5 36. 0 8 . 5 19. 0 22. 0 2 . 2 5 . 5 0 . 8 19. 0 5 . 5 36. 0 8 . 5 19. 0 22. 0 2 . 2 5 . 5 0 . 8 19. 0 5 . 5 36. 0 8 . 5 19. 0 22. 0 2 . 2 5 . 5 0 . 8 19. 0 5 . 5 mechanical specifications *(ul approved) 30. 0 7 . 8 17. 1 22. 0 2 . 2 4 . 8 0 . 8 17. 1 4 . 8 30. 0 7 . 8 17. 1 22. 0 2 . 2 4 . 8 0 . 8 17. 1 4 . 8 *as32 0 r 530 *as32 0 r 536 a s32 2 r 025 a s32 5 r 020 a s32 10015 a s32 20010 a s32 50006 a s35 0 r 550 a s35 1 r 040 a s35 2 r 035 a s35 3 r 030 a s35 5 r 025 a s35 10018 a s35 20010 *as32 1 r 030 *as32 1 r 036 part number as series inrush current limiters
mouser electronics authorized distributor click to view pricing, inventory, delivery & lifecycle information: ametherm: ? as32 1r036-100? as35 3r030? as32 1r030-100? as32 5r020? as32 1r030? as32 2r025? as32 0r536-100? as32 0r530-100? as35 0r550? as35 10018? as35 20010? as32 10015
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