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14.12 Surge suppression varistors
; M* l# F+ `7 S+ |2 vSurge suppression varistors used in order to prevent MAINS overvoltages coming into the
+ R8 j/ F4 e8 r* u8 z+ Eapparatus shall comply with IEC 61051-2.
+ [6 |4 N! }1 t$ [( z Y# j( vSuch components shall not be connected between parts connected to the MAINS and
9 y f' z" r$ K' t! B1 s/ ~ACCESSIBLE conductive parts or parts connected to them, except for earthed parts of
9 Q' V! A$ z3 LPERMANENTLY CONNECTED APPARATUS.4 a' K5 J7 t) r4 p
Reference is made to IEC 61051-2 where the following requirements apply:" L$ ?8 S7 I! F, A: f, l
– preferred climatic categories (2.1.1 of IEC 61051-2)1 u" B5 e$ {7 ]; X' D, l
• maximum lower temperature: –10 °C
# r0 B* T, q& H# {3 T0 [• minimum upper temperature: +85 °C
. W$ e; M7 [& B- |) R( f ^% B& T5 g% r• minimum duration of climatic tests: 21 days, z K- b. ~$ d; N
– maximum continuous voltages (2.1.2 of IEC 61051-2)* @$ Z) n, V4 `( H* t/ Q4 n
The minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED
4 W5 f, H( D5 Z5 C. g# B# [. v4 GSUPPLY VOLTAGE of the apparatus.
$ A0 W* ?2 h9 r+ r4 B5 k– current pulse rating (IEC 61051-2, subclause 2.1.2)* W: ^4 r m7 O' Y# G0 P* O- o
Surge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage- p; x7 \" e/ v2 y
waveform of 1,2/50 μs and current waveform of 8/20 μs.
% Y! k' s& a& R: r8 E% [; uCompliance is checked by applying the test of IEC 61051-2, group 1. After the test, the
' g& T8 [2 G V" x8 @varistor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when
; {) Y( l( p5 i( W* E5 K9 I$ Q+ R Hmeasured with the manufacturer’s specified current. |
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