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14.12 Surge suppression varistors/ d( C' P4 b$ p; d
Surge suppression varistors used in order to prevent MAINS overvoltages coming into the$ b7 b. ~4 m' B
apparatus shall comply with IEC 61051-2.
8 |3 {' k! i' |% o9 |/ ASuch components shall not be connected between parts connected to the MAINS and
3 Y9 R, f% t4 I0 F( f! xACCESSIBLE conductive parts or parts connected to them, except for earthed parts of# w. l% j' \) d& V9 }8 L M
PERMANENTLY CONNECTED APPARATUS.3 c& E# K6 E" Q: b d8 R
Reference is made to IEC 61051-2 where the following requirements apply:3 I5 Z0 F# k2 h6 f" _- T
– preferred climatic categories (2.1.1 of IEC 61051-2)) f8 c9 @: x, S4 Z4 b/ o
• maximum lower temperature: –10 °C; w6 G# {2 Q, I% a! ~7 Z! ^
• minimum upper temperature: +85 °C
$ I8 g4 c( C- t6 T% N/ u0 `• minimum duration of climatic tests: 21 days
$ `1 v5 @ I3 `4 ~8 y– maximum continuous voltages (2.1.2 of IEC 61051-2)
' T9 E, M' ]* S7 G* G3 j+ mThe minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED
+ E0 T. X8 _% X/ J* P0 m+ h. x* fSUPPLY VOLTAGE of the apparatus.
1 q6 a2 r2 v. a5 t) A# b z– current pulse rating (IEC 61051-2, subclause 2.1.2)$ z" ?* l! C3 z0 K G0 h
Surge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage% O" K4 {' {- V( w: X
waveform of 1,2/50 μs and current waveform of 8/20 μs.! d k6 g# q; X# ?
Compliance is checked by applying the test of IEC 61051-2, group 1. After the test, the; R$ o, q. N: d c3 h
varistor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when
5 H. ~: W: ]1 X' D! ?& hmeasured with the manufacturer’s specified current. |
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