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|  DSH 719' i. ]. b: X& K Y; K
" B8 W) n( t! l' X, n | Construction
% y) z% I) r6 H+ j# f | 22.106
: p9 C( H* J; R3 H b7 O+ _ | 60335-2-21(ed.5)
8 ^: s" W! b0 u6 q |
6 Q% v/ t! V: eQuestion:/ |) x" o3 q/ s2 e5 B* H
Sub-clause 22.106 of standard IEC 603325-2-21:2002 states that, a closed water heater shall incorporate a thermal cut-out providing all-pole disconnection which operates independently from the thermostat.9 S, s. w. b; S4 m% b/ Y
Can the thermal cut-out and thermostat control the same contactor, when a contactor is used or are two contactors needed, one controlled by the thermal cut-out and one controlled by the thermostat?
" c; J2 @& ?% f. R& [4 R1 VDecision:
9 N& i, N, f+ d' i- V- p; {Two contactors or relays must be used because the contactor or relay may not operate if one set of independent contacts welds closed. See also 19.14 in IEC 60335-1 Ed 4.2..: R. h9 r" \9 W. B! d* b- S
( r; L* H3 P" ^ S' [9 f
8 U+ B' P8 n. ]* ?1 C
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发表于 2012-9-8 12:11
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