application note AN581/0393 protection standards applicable to terminals ? c. politano 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 table 1 : lightning surges standards. country authority waveform ( m s) england ccitt-417 british telecom 10/700 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 the peak voltage value varies from 1 kv to 2 kv according to the country. 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) each country publishes it 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 : 1/3
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 2/3
figure 8 : 2/10 m s wave generator 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) for terminal applications this power crossing test is not widely required because only a few countries impose this standard. the typical protection arrangement consists of a crowbar device plus a ptc. 4. conclusion many different telecommunications protection standards are currently in use around the world. the sgs-thomson range of protection devices enables all of these to be covered. information furnished is believed to be accurate and reliable. however, sgs-thomson 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 life 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 3/3
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