wirewound high surge resistors whs series www.bitechnologies.com www.irctt.com www.welwyn-tt.com general note tt electronics reserves the right to make changes in product specifcation without notice or liability. all information is subject to tt electronics own data and is considered accurate at time of going to print. ? tt electronics plc 08. 12 enhanced surge & pulse energy capacity ul94-v0 fameproof protection radial taped form available surface mount z-form available rohs compliant with pb-free terminations dimensions (mm) & weight (g) type l max d max f min d nom pcb mount centres min bend radius wt. nom WHS2 9.0 3.6 19.80 0.8 12.70 1.2 0.50 whs3 14.5 5.2 24.55 20.30 1.10 whs5 16.5 7.0 23.55 22.86 1.75 whs7 25.0 8.8 28.30 31.40 4.40 WHS2 whs3 whs5 whs7 power rating at 25oc watts 2 3 5 7 5s overload rating at 25oc watts 10 15 25 35 short pulse performance see pulse performance graphs resistance range ohms 1r0-330r tcr ppm/oc 200 isolation voltage volts 250 350 500 700 resistance tolerance % <20r: 5 20r: 1, 2, 5 standard values e12 preferred thermal impedance oc/watt 110 82 54 35 ambient temperature range oc -55 to +155 construction a high purity ceramic substrate is assembled with interference ft end caps to which are welded the terminations. the resistive element is wound on the substrate and welded to the caps. flameproof silicone cement coating is applied priorto marking with indelible ink. the components are then leadformed if required and packed. electrical data physical data no limiting element voltage applies to this series; the rated voltage is (p.r). f d d l
wirewound high surge resistors whs series www.bitechnologies.com www.irctt.com www.welwyn-tt.com general note tt electronics reserves the right to make changes in product specifcation without notice or liability. all information is subject to tt electronics own data and is considered accurate at time of going to print. ? tt electronics plc 08. 12 maximum typical load at rated power: 1000hrs @ 25c r% 5 +0.001: 3 dry heat: 1000hrs @ 200c r% 5 +0.001: 3 short term overload r% 5 +0.001: 1 derating from rated power @25c zero at 280c (see thermal performance graph). climatic r% 5 +0.001: 2 climatic category 55/200/56 trc & vibration r% 5 +0.001: 1 robustness & solder heat r% 5 +0.001: 1 long term damp heat (56 days) r% 5 +0.001: 1 terminations material: hot tin dipped copper wire strength: the terminations meet the requirements of iec 68.2.21 solderability: the terminations meet the requirements of iec 115-1 clause 4.17.3.2 marking WHS2, and whs3 resistors are marked with four colour bands in conformance with iec62 . whs5 and whs7 resistors are legend marked with type reference, resistance value and tolerance. flammability the resistor coating will not burn or emit incandescent particles under any condition of applied temperature or power overload. solvent resistance the body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. performance data pulse performance 1 10 10 0 11 01 00 100 0 en er gy ( j oul es) va lu e (o hm s) surg e / pulse ener gy c apacit y (s in gl e or l ow r ep et it io n ra te , r < 5% ) whs5 whs3 WHS2 whs7
0 20 40 60 80 100 05 01 00 15 02 00 25 03 00 350 am bi en t te mp er at ur e ( c) pr opo rt io n of rat ed p ow er ( %) ambient temperature c 0 50 100 150 200 250 300 01 23 45 67 89 10 te mp er at ur e ri se ( c ) whs7 whs5 whs3 WHS2 temperature rise (c) power (w) bo d y t em p erature rise wirewound high surge resistors whs series www.bitechnologies.com www.irctt.com www.welwyn-tt.com general note tt electronics reserves the right to make changes in product specifcation without notice or liability. all information is subject to tt electronics own data and is considered accurate at time of going to print. ? tt electronics plc 08. 12 application notes 1. if the resistors are to dissipate full rated power, it is recommended that the terminations should not be soldered closer than 4mm from the body. 2. due to operating temperature limits imposed by some pcb materials, derating may be necessary. the surface temperature rise at the centre of the body is shown under thermal performance. 3. WHS2, whs3, whs5 resistors can also be supplied with goalpost or lancet pre-formed leads. radial form is available on WHS2 and whs3 only. WHS2, whs3, and whs5 are also available in an smd format with z formed leads and packed in blister tape. see the z-form datasheet for details http://www.welwyn-tt.com/pdf/datasheet/z-form.pdf thermal performance 0. 1 1 10 11 01 00 100 0 p eak v ol ta ge ( kv ) va lu e (o hm s) s p eak v olta ge l imit (1 0 pu ls es a t 30s in te rv al s, r < 5% ) no te t he v ol t age s ho wn i s th e ne tt v ol t age a cr oss th e re si st or . at l ow va lu es , th e ge ne ra to r ope n ci rc ui t vo lt age w ill b e hi gh er d ue t o th e ge ne ra to r' s 2 oh m in te rn al i m pedan ce .
WHS2 C 100r j a25 dimensions mm b c WHS2 52 5 whs3 67 10 whs5 63 10 *whs7 85 10 *an offset lead length is available for whs7 series. consult factory for details ordering procedure example: WHS2 at 100 ohms and 5% tolerance in ammo pack box of 2500 pieces - wirewound high surge resistors whs series www.bitechnologies.com www.irctt.com www.welwyn-tt.com general note tt electronics reserves the right to make changes in product specifcation without notice or liability. all information is subject to tt electronics own data and is considered accurate at time of going to print. ? tt electronics plc 08. 12 packaging the standard packaging for whs is taped. the critical dimensions are shown in figure 1. the component wires will not protrude beyond the outside edge of the tapes. taped product is then packed into boxes or onto reels. see ordering procedure for details. alternative packaging is available by request. pre-formed resistors are supplied loose packed in plastic bags or boxes. type value (use iec62 code) tolerance (use iec62 code) packing a25 tape WHS2 2500/box standard a1 whs3 1000/box t075 ammo whs5 750/reel t07 whs7 700/reel f 1% g 2% j 5% radial goalpost lancet z-form b f1 f2 -f2 < 1.4mm 6 6 figure 1 c
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