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5.12 For heating appliances and combined appliances, when it is specified that the. ^; h; E; ^4 w" V
appliance has to operate at a power input multiplied by a factor, this applies only to heating& B7 L; p3 m* X# P$ v: u
elements without appreciable positive temperature coefficient of resistance.
2 w' T$ r6 H! P7 ~, KFor heating elements with appreciable positive temperature coefficient of resistance, other than( ^! x6 {8 P& j
PTC heating elements, the supply voltage is determined by supplying the appliance at rated
: s/ ]8 f* D9 T/ y/ ^voltage until the heating element reaches its operating temperature. The supply voltage is then
7 a) s% x8 M" q6 A4 N! V! I' FCopyright International Electrotechnical Commission
) P; I( R9 n) Irapidly increased to the value necessary to give the power input required for the relevant test,
% u4 ^) a% ^0 C. j0 p4 rthis value of the supply voltage being maintained throughout the test.
5 f" ]+ T; |; M# g+ V6 s: w; QNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input( j* C0 B. a, ^* v9 H
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
8 e4 Q% C3 j1 c+ }, k5.13 The tests for appliances with PTC heating elements and for heating appliances and7 d& w4 t- P# P8 Q
combined appliances where the heating elements are supplied via a switch mode power* ]! ?4 ]; M# A% l' R; T [5 O2 }$ P5 X' Z
supply are carried out at a voltage corresponding to the specified power input.! r: K1 G0 i! ~6 i) F0 ?
When a power input greater than the rated power input is specified, the factor for multiplying4 U6 B" z$ m* [; b: n2 |3 g. o
the voltage is equal to the square root of the factor for multiplying the power input. |
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发表于 2012-10-14 22:14
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