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5.12 For heating appliances and combined appliances, when it is specified that the
0 S0 ^5 b. { Q, I5 Tappliance has to operate at a power input multiplied by a factor, this applies only to heating
# [, W5 U/ j0 a$ y" kelements without appreciable positive temperature coefficient of resistance.3 e# l& X) n$ C ]( W, B
For heating elements with appreciable positive temperature coefficient of resistance, other than
( K$ r. j! B3 d1 o* ZPTC heating elements, the supply voltage is determined by supplying the appliance at rated# j* Z6 `4 O2 @4 _
voltage until the heating element reaches its operating temperature. The supply voltage is then
9 V7 `7 O' r% S3 X0 H$ kCopyright International Electrotechnical Commission
# c, y: w0 S' Hrapidly increased to the value necessary to give the power input required for the relevant test,
1 k; L5 u1 D! A+ n5 r% tthis value of the supply voltage being maintained throughout the test.
; V. H% w7 N, L! W% y$ _NOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
: d+ T$ {% Y3 V pof the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
* R7 x3 x* G- t( ^$ K; c. r: s5.13 The tests for appliances with PTC heating elements and for heating appliances and
6 [- R. l( o* m4 ucombined appliances where the heating elements are supplied via a switch mode power
% C, H4 K* Q# A% d# h; x, msupply are carried out at a voltage corresponding to the specified power input.
, L+ h, d8 \! sWhen a power input greater than the rated power input is specified, the factor for multiplying
; q3 P! Q9 e! N K' ethe 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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