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5.12 For heating appliances and combined appliances, when it is specified that the
1 O" {, }. |& t7 Vappliance has to operate at a power input multiplied by a factor, this applies only to heating5 A7 g' M; X8 G& C
elements without appreciable positive temperature coefficient of resistance.
# J% }+ K) j. I4 L3 j: kFor heating elements with appreciable positive temperature coefficient of resistance, other than, ~9 A" k" o+ x' }( P
PTC heating elements, the supply voltage is determined by supplying the appliance at rated0 M( C/ M$ g1 e$ S! g' Z3 B
voltage until the heating element reaches its operating temperature. The supply voltage is then
+ x7 o' q6 ] g; b& ?5 xCopyright International Electrotechnical Commission, Q4 ]7 O; X* k& B6 Z4 M6 u
rapidly increased to the value necessary to give the power input required for the relevant test,
( U. K+ c( Q" b( _- cthis value of the supply voltage being maintained throughout the test.
, Z. i& L; ]( G0 H/ }NOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input0 d; T9 { K& c+ u5 R
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
- c( j+ t( o. m j5.13 The tests for appliances with PTC heating elements and for heating appliances and
( I S: G5 b6 I* C' Qcombined appliances where the heating elements are supplied via a switch mode power% v9 }7 q7 e8 W4 d; Z& M3 N+ z
supply are carried out at a voltage corresponding to the specified power input.
6 r) l; p- |8 l2 D0 O* eWhen a power input greater than the rated power input is specified, the factor for multiplying
0 j" b+ r( j' p; A" T. Wthe 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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