IEC 60850-2007 pdf Railway applications一 Supply voltages of traction systems

3.1 3 suppl y vol tage dip sudden reduction of the supply voltage to a value of less than U mi n2 , followed by a voltage recovery after a short period of time . Conventionally , the duration of a voltage dip is between 1 0 ms and 1 min . The depth of a voltage dip is defined as the difference between the minimum r.m.s. voltage during the voltage dip and the nominal voltage U n . Voltage changes which do not reduce the supply voltage to less than U mi n2 are not considered to be dips 3.1 4 s upply interruption condition in which the voltage at the supply-terminals is lower than 1 % of the nominal voltage U n . A supply interruption can be classified as pre-arranged , when consumers are informed in advance , to allow the execution of scheduled works on the distribution systems , or accidental , caused by permanent or transient faults , mostly related to external events , equipment failures or interference . An accidental interruption is classified as • a long interruption (Ionger than 3 min) caused by a permanent fault , • a short interruption (up to 3 min) caused by a transient fault (see EN 501 60). 3.1 5 c ont a ct line conductor system for supplying electric energy to vehicles through current-collecting equipment [IEV 81 1 -33-01 ]
NOTE 2 In practice , the variation of frequency is more closely controll ed in Europe than stated above. Veh icl es will ope r ate only wi th in the frequency tolerances for 15 kV/16 ,7 Hz f rom 16 , 17 Hz to 17 Hz and for 25 kV/50 Hz range from 49 Hz to 51 Hz. If the frequency is out of th is range , the vehicl es performance may be reduced or the veh i cle dri ves may be disconnected The effects of the frequency variations may be examined by the railway operators to ensure the absence of harmful consequences on the train signalling .