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5.12 For heating appliances and combined appliances, when it is specified that the
) K, i- s% F, ~; c: O& r4 Gappliance has to operate at a power input multiplied by a factor, this applies only to heating, U" W) C6 D0 e' R
elements without appreciable positive temperature coefficient of resistance.
% Q7 ^0 x3 c3 Q; o l Y% I$ T2 lFor heating elements with appreciable positive temperature coefficient of resistance, other than- g# ^2 G0 q6 x# ~; D* y# ^" O/ y
PTC heating elements, the supply voltage is determined by supplying the appliance at rated7 Y9 u1 e( r' g! J- Z2 \
voltage until the heating element reaches its operating temperature. The supply voltage is then5 h# f. `; v/ }1 ~4 l; l% q% @* e
Copyright International Electrotechnical Commission
% k+ _- q+ V4 x* j* q. arapidly increased to the value necessary to give the power input required for the relevant test,
+ s& _' c5 c6 U1 R7 o. h wthis value of the supply voltage being maintained throughout the test.
+ ^- ^) v$ I7 r8 F, F% wNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input- O6 Q# j( \# `4 }
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.8 j+ Y# ~3 R! R; B9 m- o- o
5.13 The tests for appliances with PTC heating elements and for heating appliances and
T% J u& S8 S5 K. z. L( |7 R6 ccombined appliances where the heating elements are supplied via a switch mode power
0 `& ]+ s w% B. T/ fsupply are carried out at a voltage corresponding to the specified power input.
; c3 h8 i! K& f, tWhen a power input greater than the rated power input is specified, the factor for multiplying; |& R# u. y$ Y% @) j8 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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