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14.12 Surge suppression varistors
4 p7 @" @; \% w$ }Surge suppression varistors used in order to prevent MAINS overvoltages coming into the* M+ [/ y4 f" D# m/ v
apparatus shall comply with IEC 61051-2.
( C& M5 }; }/ f( G8 A) {Such components shall not be connected between parts connected to the MAINS and/ D7 I( q8 j2 F4 m
ACCESSIBLE conductive parts or parts connected to them, except for earthed parts of
! o; T. `# s+ @# y; [PERMANENTLY CONNECTED APPARATUS.
/ k% [$ E1 T) K7 s3 W5 D/ \( N( JReference is made to IEC 61051-2 where the following requirements apply:& B7 b! [2 G+ y, B$ y5 [+ i
– preferred climatic categories (2.1.1 of IEC 61051-2)! ~ A. q5 X$ z: ?; }
• maximum lower temperature: –10 °C; @! v7 Z- B9 [+ s
• minimum upper temperature: +85 °C. x/ |) I( Z& O
• minimum duration of climatic tests: 21 days# I6 E' w6 b$ C. k
– maximum continuous voltages (2.1.2 of IEC 61051-2), y9 i0 d8 z: X, K, v q% X3 N
The minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED
6 ]0 _; v+ S$ K- B d' S$ t K( H! r( lSUPPLY VOLTAGE of the apparatus.
+ B& o) H% H8 P/ [– current pulse rating (IEC 61051-2, subclause 2.1.2)6 N' t" C5 W2 c2 w1 c! G
Surge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage7 A# T- N8 G5 q6 |
waveform of 1,2/50 μs and current waveform of 8/20 μs.
; S3 K/ g! i! m& M2 G7 zCompliance is checked by applying the test of IEC 61051-2, group 1. After the test, the+ D) S; ?1 M0 B$ O3 x* G- I! W
varistor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when6 Q0 F: r# }% C, X0 j
measured with the manufacturer’s specified current. |
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