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14.12 Surge suppression varistors
& t8 w& S$ Q6 ~: f+ @Surge suppression varistors used in order to prevent MAINS overvoltages coming into the
4 S) e/ N p6 l( _0 qapparatus shall comply with IEC 61051-2.
# R3 g( o" W% x+ r; D; e( |Such components shall not be connected between parts connected to the MAINS and
* L3 n2 [' p. [/ c/ N: V" d# OACCESSIBLE conductive parts or parts connected to them, except for earthed parts of1 W5 Z9 T; L% ~- d* I
PERMANENTLY CONNECTED APPARATUS.4 d0 ^* u! R! f6 \
Reference is made to IEC 61051-2 where the following requirements apply:
9 Q7 U ]' s4 \" a( Z$ M– preferred climatic categories (2.1.1 of IEC 61051-2)
6 Q0 N- Y: s5 ]• maximum lower temperature: –10 °C4 m5 K6 a& O6 D& ~
• minimum upper temperature: +85 °C; [5 T* f0 s7 Q* B# S# l! q- I9 e6 ^! l8 E
• minimum duration of climatic tests: 21 days
* S; h+ n6 l. M- v! G* B( B– maximum continuous voltages (2.1.2 of IEC 61051-2)9 q% m" n3 R- p r
The minimum value of the maximum continuous a.c. voltage shall be 1,2 times the RATED y7 h: y3 f. s* U) _# f- f
SUPPLY VOLTAGE of the apparatus.
; v! s2 U' A! p: \– current pulse rating (IEC 61051-2, subclause 2.1.2)7 V5 P6 p2 G( O& _; X A
Surge suppression varistors shall withstand a combination pulse of 6 kV/3 kA with voltage& d# ?) @- {9 @6 G0 b0 c+ X
waveform of 1,2/50 μs and current waveform of 8/20 μs.
# J3 ], ]1 O( Q' {. }, `) OCompliance is checked by applying the test of IEC 61051-2, group 1. After the test, the
" Q$ i- v5 j l; x6 J6 Gvaristor voltage (as defined in IEC 61051) shall not have changed by more than 10 % when4 v" G0 c/ A! E9 l$ Y8 n
measured with the manufacturer’s specified current. |
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