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14.12 Surge suppression varistors
. U3 S! I5 Z5 r4 H1 H$ @) E7 lSurge suppression varistors used in order to prevent MAINS overvoltages coming into the
, O! X B/ ~7 X) S8 gapparatus shall comply with IEC 61051-2.
9 _! A. H, s( p J1 hSuch components shall not be connected between parts connected to the MAINS and
0 A1 ]4 g5 [# N& N' VACCESSIBLE conductive parts or parts connected to them, except for earthed parts of, [ \! Q" b S9 N& D- e
PERMANENTLY CONNECTED APPARATUS.
1 j( W) H5 X1 R! q4 g2 ?Reference is made to IEC 61051-2 where the following requirements apply:
5 i* s( y% c. f- |" K– preferred climatic categories (2.1.1 of IEC 61051-2)! U# T5 q7 E+ @" d5 z! w
• maximum lower temperature: –10 °C
8 t) W0 L) K: o. V• minimum upper temperature: +85 °C
: y" N3 \9 J9 g3 S• minimum duration of climatic tests: 21 days
# |( n! y+ R7 D9 N' a– maximum continuous voltages (2.1.2 of IEC 61051-2)
) ]- h9 D- x# Q& L0 cThe minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED
% w+ r, d+ ? b: ySUPPLY VOLTAGE of the apparatus.0 S7 k3 W* B3 h! A- w; P
– current pulse rating (IEC 61051-2, subclause 2.1.2)
/ Z* u% X8 E5 T/ }Surge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage" S3 v R. ]1 A+ }
waveform of 1,2/50 μs and current waveform of 8/20 μs.! ?" r# s* }/ B e* D
Compliance is checked by applying the test of IEC 61051-2, group 1. After the test, the% z, \5 Z8 M; t: o& S
varistor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when& q! t' C- \! {! n
measured with the manufacturer’s specified current. |
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