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5.12 For heating appliances and combined appliances, when it is specified that the
0 T% F o6 N4 J6 }5 Y1 ~, L+ J. jappliance has to operate at a power input multiplied by a factor, this applies only to heating
. q6 Y% o$ b* I p$ Delements without appreciable positive temperature coefficient of resistance.' D: J2 O: m7 A6 J q
For heating elements with appreciable positive temperature coefficient of resistance, other than5 b f% _7 N( m) M( V
PTC heating elements, the supply voltage is determined by supplying the appliance at rated! T! B5 v0 Q) G3 n* e
voltage until the heating element reaches its operating temperature. The supply voltage is then% e' r; e+ c7 M+ ? i* R
Copyright International Electrotechnical Commission
/ g% `! I5 W3 m6 o7 l) {1 [+ V/ ]; Irapidly increased to the value necessary to give the power input required for the relevant test,
; b) d4 f7 r$ [ zthis value of the supply voltage being maintained throughout the test.4 b* b% R2 O3 v6 h4 g, ^' A
NOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
* q+ o7 L4 g" x2 _* h% \; vof the appliance in cold condition differs by more than 25 % from the power input at operating temperature., t5 C- @& a( X
5.13 The tests for appliances with PTC heating elements and for heating appliances and: J6 ]9 U& Y9 S8 L8 J# m5 x
combined appliances where the heating elements are supplied via a switch mode power
% y- X% P# @# C" q' K d9 X/ lsupply are carried out at a voltage corresponding to the specified power input.- w X7 `4 @- ^: w7 m/ w V
When a power input greater than the rated power input is specified, the factor for multiplying+ q4 `1 F8 `& |
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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