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5.12 For heating appliances and combined appliances, when it is specified that the8 _3 w- N5 e7 z) g
appliance has to operate at a power input multiplied by a factor, this applies only to heating, I9 y0 a7 k" ~1 J% ^. g
elements without appreciable positive temperature coefficient of resistance.
; q3 R( W- u2 ]/ {" u- Z7 ^For heating elements with appreciable positive temperature coefficient of resistance, other than
3 ]: x: \* \3 w) U- b( xPTC heating elements, the supply voltage is determined by supplying the appliance at rated4 q( M% t# R/ P
voltage until the heating element reaches its operating temperature. The supply voltage is then6 g0 O+ }- W" x
Copyright International Electrotechnical Commission: b% C1 z! t# o) Y# N
rapidly increased to the value necessary to give the power input required for the relevant test," M+ X q0 ~. H9 R' Q `
this value of the supply voltage being maintained throughout the test.
7 q4 o) V7 } XNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
Q) o$ @' N& |* q7 T3 V w+ ^of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
2 O& o% ]6 G# H- }8 W. |5 A5.13 The tests for appliances with PTC heating elements and for heating appliances and
" W' c* ]% \3 N2 Acombined appliances where the heating elements are supplied via a switch mode power
4 `$ l2 L3 G7 E( q+ Hsupply are carried out at a voltage corresponding to the specified power input.
( [! T0 \. ]: ]6 f8 \; VWhen a power input greater than the rated power input is specified, the factor for multiplying- \3 _: a/ L: ~' g; t# U+ P% m; A
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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