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|  DSH 719( h2 y" f$ d8 p" |6 U
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3 |$ P5 J) D) P9 V$ F | 22.106 H: I$ D6 v. B2 g7 n/ Z8 |
| 60335-2-21(ed.5)# V5 `$ ?" f5 f5 F; m
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7 l( Z1 n; o2 R& H6 q, tQuestion:
: I+ a( a' q* y, ]8 V! bSub-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.8 H, P/ |, [+ ?7 x! l8 ~# ?6 A
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?6 w |: B9 @/ K9 q
Decision:: i: |: t, w' ^4 r6 _" F
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.. a$ r5 o1 ]* l! C6 c% k0 y/ ^
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发表于 2012-9-8 12:11
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