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14.12 Surge suppression varistors3 s$ O, K8 j9 h" y! u8 y
Surge suppression varistors used in order to prevent MAINS overvoltages coming into the8 G$ F" E5 B# K
apparatus shall comply with IEC 61051-2.
V* M8 K2 b% M' v+ V! |Such components shall not be connected between parts connected to the MAINS and+ F+ R7 C% M0 s+ A! a
ACCESSIBLE conductive parts or parts connected to them, except for earthed parts of8 I8 h. |7 {; ?9 p
PERMANENTLY CONNECTED APPARATUS.
/ f4 U; U& p0 F z FReference is made to IEC 61051-2 where the following requirements apply:
* j- N9 D G* n4 O' S– preferred climatic categories (2.1.1 of IEC 61051-2)2 \/ W$ Y& u# `3 D T- `. W' ?
• maximum lower temperature: –10 °C
" C9 e. z: A+ j" G/ j" u1 k• minimum upper temperature: +85 °C7 f$ A1 J. {$ Z
• minimum duration of climatic tests: 21 days" r; t, J' E Z' L9 G
– maximum continuous voltages (2.1.2 of IEC 61051-2)
) g p! Y! X8 C" hThe minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED
/ F4 D. R5 N1 _6 c9 b/ C" TSUPPLY VOLTAGE of the apparatus.
3 M! q2 U2 u* w& r5 T3 M– current pulse rating (IEC 61051-2, subclause 2.1.2)! U' C- C' N0 L" d2 E
Surge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage( L. _: @$ l% W- N2 R) r
waveform of 1,2/50 μs and current waveform of 8/20 μs.8 ?6 K' E T4 J$ t4 m, Y5 X, H
Compliance is checked by applying the test of IEC 61051-2, group 1. After the test, the
$ o/ ?3 z1 R7 J Y% r Z. V/ u" Svaristor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when
; d) }% w7 L4 ]7 n! J7 A: J* omeasured with the manufacturer’s specified current. |
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