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14.12 Surge suppression varistors
, `8 ~) \0 t& n8 T! b! r+ aSurge suppression varistors used in order to prevent MAINS overvoltages coming into the! R( B: C' k# U. T
apparatus shall comply with IEC 61051-2.
6 {6 e' r) `! y; O+ FSuch components shall not be connected between parts connected to the MAINS and( t' n- Z( H8 |& c
ACCESSIBLE conductive parts or parts connected to them, except for earthed parts of" u+ j' i, f0 Y+ u
PERMANENTLY CONNECTED APPARATUS.& |" t0 P/ J: R" A' o* w [" Y2 ^
Reference is made to IEC 61051-2 where the following requirements apply:
* U7 }" N6 d+ c+ _8 j8 O* I– preferred climatic categories (2.1.1 of IEC 61051-2)3 z) ~5 @% j0 b4 n$ [% _5 V; u3 V
• maximum lower temperature: –10 °C0 Q, ~6 G1 W# ]) `
• minimum upper temperature: +85 °C
+ _4 P# q2 v7 ?8 i* o• minimum duration of climatic tests: 21 days
4 n3 ^! q# w! k" v! s4 `$ c! M– maximum continuous voltages (2.1.2 of IEC 61051-2)0 q+ f% y9 x5 y
The minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED
1 i+ w$ G4 b6 u/ B: [6 w; y5 Q3 rSUPPLY VOLTAGE of the apparatus.9 p2 ~4 C: L4 Y- m2 p: j/ k
– current pulse rating (IEC 61051-2, subclause 2.1.2)
( O* Z# O3 R. a1 C D: L" {/ OSurge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage
. t: p; `# h, d1 jwaveform of 1,2/50 μs and current waveform of 8/20 μs.
, N& b, ]! r! V6 y3 mCompliance is checked by applying the test of IEC 61051-2, group 1. After the test, the% [7 k4 k: n/ U+ o/ s9 S1 t
varistor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when
% [$ D# b% [" _ P t* nmeasured with the manufacturer’s specified current. |
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