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5.12 For heating appliances and combined appliances, when it is specified that the
1 D/ {' b5 M1 i4 {1 ~/ Y- _! Qappliance has to operate at a power input multiplied by a factor, this applies only to heating
, h2 d' f8 C# Felements without appreciable positive temperature coefficient of resistance.' [6 ]$ E0 Q( O! U
For heating elements with appreciable positive temperature coefficient of resistance, other than
A, R1 c N" s8 W+ R9 m) _" C2 Q; }PTC heating elements, the supply voltage is determined by supplying the appliance at rated
( L( `/ a6 u9 t* e! w! i) uvoltage until the heating element reaches its operating temperature. The supply voltage is then
* y! |# Y6 }& zCopyright International Electrotechnical Commission. O( x. b6 I; f
rapidly increased to the value necessary to give the power input required for the relevant test,
0 M% z/ m9 ^3 O: }! T4 o- T- h2 c% gthis value of the supply voltage being maintained throughout the test.
. k) D# x5 ~; H2 {, E* uNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input F) s- R5 V7 A- C! t, G, t
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
( n3 p; r) K, {' u! c7 e5.13 The tests for appliances with PTC heating elements and for heating appliances and
* B' g' i) I' Q7 pcombined appliances where the heating elements are supplied via a switch mode power
. ^3 ?$ q. H8 \$ }# I# @+ Usupply are carried out at a voltage corresponding to the specified power input.
, B, g1 P3 H# c. O$ s! ?When a power input greater than the rated power input is specified, the factor for multiplying! B9 D! _. g# P9 S5 h3 g
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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