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14.12 Surge suppression varistors1 j+ @2 u4 @! D5 N
Surge suppression varistors used in order to prevent MAINS overvoltages coming into the
. V& k* G! O" ~; d$ eapparatus shall comply with IEC 61051-2.
4 _# Z, G' W c! M3 OSuch components shall not be connected between parts connected to the MAINS and4 V! m) i/ S) B' H' f) Y
ACCESSIBLE conductive parts or parts connected to them, except for earthed parts of$ k3 M: S. b! ? ~( m* i
PERMANENTLY CONNECTED APPARATUS.
. O: K1 J/ C) y$ H+ S% oReference is made to IEC 61051-2 where the following requirements apply:. V. B! a* |) J# B
– preferred climatic categories (2.1.1 of IEC 61051-2) {) v7 \ W2 M
• maximum lower temperature: –10 °C
4 `- y9 T8 r J, |$ j; E; G• minimum upper temperature: +85 °C5 {! l" R7 ?8 T7 Z5 X
• minimum duration of climatic tests: 21 days, u* f% S, ^6 A3 X9 W1 h' T
– maximum continuous voltages (2.1.2 of IEC 61051-2)3 s: K; B( D0 t1 E
The minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED
' S4 `. A ?3 P* s. MSUPPLY VOLTAGE of the apparatus./ R/ T! |+ o# n
– current pulse rating (IEC 61051-2, subclause 2.1.2)$ \* W) ]5 n8 k1 v% F" ^3 X, F
Surge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage# i( r, |; O) K0 U
waveform of 1,2/50 μs and current waveform of 8/20 μs.
& D$ N* d* X: ?# D6 U: QCompliance is checked by applying the test of IEC 61051-2, group 1. After the test, the
: b( L; n: Y- V% V7 h4 k8 |varistor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when# y4 s6 F4 Z8 |4 q- r
measured with the manufacturer’s specified current. |
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