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5.12 For heating appliances and combined appliances, when it is specified that the
5 {( }! ~0 b. q& b; @appliance has to operate at a power input multiplied by a factor, this applies only to heating5 J# t' a& |! P& T+ R
elements without appreciable positive temperature coefficient of resistance.
0 L0 k) r0 |" w" E SFor heating elements with appreciable positive temperature coefficient of resistance, other than
# U) n, Y! v7 ?& B( ]PTC heating elements, the supply voltage is determined by supplying the appliance at rated
5 S5 o6 r2 z5 L( S' x. Tvoltage until the heating element reaches its operating temperature. The supply voltage is then
i! ~% T& \; Z( |8 xCopyright International Electrotechnical Commission
- T( X9 P7 T% {" Z# Krapidly increased to the value necessary to give the power input required for the relevant test,- A4 w: o; c- }. j) Z
this value of the supply voltage being maintained throughout the test.
8 C/ i3 b& `0 s: o4 LNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
# F0 m7 z2 s8 W: o# h; pof the appliance in cold condition differs by more than 25 % from the power input at operating temperature.* C' z9 e& P3 m6 B4 E4 o8 V
5.13 The tests for appliances with PTC heating elements and for heating appliances and% a& j' {9 `, j4 Q/ x
combined appliances where the heating elements are supplied via a switch mode power; |# N f( ?1 x
supply are carried out at a voltage corresponding to the specified power input.& f( I- n b R0 l+ U! O9 G
When a power input greater than the rated power input is specified, the factor for multiplying2 K0 D- W8 j, |6 C7 U
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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