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5.12 For heating appliances and combined appliances, when it is specified that the
- y2 O- B/ W/ s Tappliance has to operate at a power input multiplied by a factor, this applies only to heating
) I* M: l5 G3 ^4 G {$ Celements without appreciable positive temperature coefficient of resistance.
. k. o2 I8 g h& Y6 e7 KFor heating elements with appreciable positive temperature coefficient of resistance, other than' [( T4 {5 u7 H4 ^2 H) O
PTC heating elements, the supply voltage is determined by supplying the appliance at rated% n# G) X/ Q8 I, ~; b- {
voltage until the heating element reaches its operating temperature. The supply voltage is then
& g% h6 l& a) q2 ]( g0 N. n& xCopyright International Electrotechnical Commission4 ^* _0 a- e- l9 v/ u' D
rapidly increased to the value necessary to give the power input required for the relevant test,. J" F* x2 y$ F+ d0 ~
this value of the supply voltage being maintained throughout the test.1 Y# @, C3 ?$ }. n( d6 p- i$ ], J
NOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
, L6 K, r; m, k |4 P: Gof the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
. b: s& ]* j" U( f+ r4 ?5.13 The tests for appliances with PTC heating elements and for heating appliances and
* F& X6 S) ^2 K; v: \3 rcombined appliances where the heating elements are supplied via a switch mode power
& N( t, P; r# N; q4 t j1 Z# G2 isupply are carried out at a voltage corresponding to the specified power input.
4 `" a6 b6 O5 s! c c( f) GWhen a power input greater than the rated power input is specified, the factor for multiplying
' V2 ~ q! u9 athe 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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