application note AN583/0393 applicable to switching equipment protection standards ? a. bremond 1. introduction the purpose of this document is to summarize the main telecommunication standards with regard to the protection requirements against two types of overvoltage : - lightning surges - power crossing perturbations figure 1 : standard wave 2. lightning surges the lightning overvoltage is simulated by a biexponentional wave, which is defined by the rise time t1 and the duration t2 between the start and the time at which the falling edge crosses half the peak value (fig.1) country authority waveform ( m s) england british telecom 10/700 france ptt 0.5/700 germany bundespost 10/700 italy sip 10/700 1/1000 spain company telefonica de espana 1/1000 sweden televerket 10/700 switzerland ptt - betriebe 10/700 1.2/50 usa bell 10/1000 10/360 2/10 fcc 10/560 10/160 2/10 each country publishes its standard, which can be summarized by the times t1 and t2, the peak voltage of the wave and the surge generator diagram. table 1 gives on inexhaustive list of the standards . table 1 : lightning surge standards 1/4
figure 2 : 10/700 m s wave generator figure 3 : 1.2/50 m s wave generator figure 6 : 1/1000 m s wave generator figure 7 : 10/160 m s wave generator figure 5 : 10/560 m s wave generator figure 4 : 0.5/700 m s wave generator the following figures give the schematics of the surge generators mainly used : ? application note 2/4
figure 9 : crossing simulation generator 3. crossing or proximity with mains ac lines : crossing or proximity is simulated by a sine wave generator (50 or 60 hz) connected through a series resistor for a defined time (fig.9). 4. conclusion telecommunications is a field in which the protection against overvoltages is well defined by standards. the sgs-thomson range of protection devices enables all of these to be covered. country voltage volts rms series resistor (ohms) duration england 0 to 250 0 to 650 0 to 430 (50 hz) 40 to 400 150 150 15mn 1s 2s france 0 to 1000 > 1000 (50 hz) 20 3000 trains of - 1s oono - 1s ooffo -1s oono 10 times with 10mn between trains germany 300 (50 hz or 16.6hz) 600 200 ms italy 300 650 220 600 200 10 or 600 500 ms 500 ms 15 mn usa 0 - 50 50 - 100 100 - 600 150 600 600 15 mn 15 mn 60 x 1s application table 2 give some example of crossing simulations. note : protection resistors on the line card inputs decrase the peak surge current. these elements have to be taken into account during the line card design to optimize the protection function. figure 8 : 2/10 m s wave generator table 2 : power crossing simulations ? application note 3/4
information furnished is believed to be accurate and reliable. however, sgs-thom son microelectronics assumes no responsability for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of sgs-thomson microelectronics. specifications mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously supplied. sgs-thomson microelectronics products are not authorized for use as critical components in lif e support devices or systems without express written approval of sgs-thomson microelectronics. ? 1995 sgs-thomson microelectronics - printed in italy - all rights reserved. sgs-thomson microelectronics group of companies australia - brazil - france - germany - hong kong - italy - japan - korea - malaysia - malta - morocco - the netherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. ? application note 4/4
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