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14.12 Surge suppression varistors2 N k- X- I$ _: g, I, q" c
Surge suppression varistors used in order to prevent MAINS overvoltages coming into the
8 k* s% U# [# L; I% ]( o Vapparatus shall comply with IEC 61051-2. O$ K/ E! @6 r& y- ~* S5 C; B
Such components shall not be connected between parts connected to the MAINS and
, i& g7 ?& U, }1 x1 vACCESSIBLE conductive parts or parts connected to them, except for earthed parts of
5 W; t6 ]" y. O3 S8 lPERMANENTLY CONNECTED APPARATUS.( L& Y' I% s3 t4 |5 }4 z) \
Reference is made to IEC 61051-2 where the following requirements apply:
8 f d6 n0 p; |– preferred climatic categories (2.1.1 of IEC 61051-2)
! j! r: a$ a" }• maximum lower temperature: –10 °C
x9 F0 }7 s' h3 O8 a f) y5 [• minimum upper temperature: +85 °C2 A. n2 R" z# M' ]1 r3 m
• minimum duration of climatic tests: 21 days
- N p( S1 L- N# \2 Z3 S9 H9 O( ]– maximum continuous voltages (2.1.2 of IEC 61051-2)
" t |2 h. q9 ?, iThe minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED; ?5 O- f! Y; w/ w, O& i! B
SUPPLY VOLTAGE of the apparatus.
a& G* I9 s0 }– current pulse rating (IEC 61051-2, subclause 2.1.2)
8 D4 ~0 o8 t3 s) X5 fSurge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage
' o8 g1 {8 H- U" ?% L- A5 e- \waveform of 1,2/50 μs and current waveform of 8/20 μs.
5 W# O5 g0 i. Z( FCompliance is checked by applying the test of IEC 61051-2, group 1. After the test, the; U, T! s; ]/ d0 I+ k& @; n+ @
varistor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when! |# x5 |6 j7 @3 A r
measured with the manufacturer’s specified current. |
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