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5.12 For heating appliances and combined appliances, when it is specified that the
- G1 R- R/ x, V( ]2 sappliance has to operate at a power input multiplied by a factor, this applies only to heating
0 `) x; ]5 f8 g9 _$ m7 \elements without appreciable positive temperature coefficient of resistance.
. ^9 G W- `+ `& Q6 M; IFor heating elements with appreciable positive temperature coefficient of resistance, other than
. E3 N% ?+ v: l9 u+ G% hPTC heating elements, the supply voltage is determined by supplying the appliance at rated8 z* c; X! X3 s1 ?9 F3 c1 r
voltage until the heating element reaches its operating temperature. The supply voltage is then5 l. b) }: ^- T5 r* A
Copyright International Electrotechnical Commission
6 ?3 ^) K$ }, `$ X$ [% n4 B2 \rapidly increased to the value necessary to give the power input required for the relevant test,
; w5 y# Y: N x. d2 ]this value of the supply voltage being maintained throughout the test.
9 R" C) m6 }* T7 c& oNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input* y8 Y& X* f2 v
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
# \. m9 q9 ~+ Z5 S9 R; z5 B2 u5.13 The tests for appliances with PTC heating elements and for heating appliances and4 ~; T0 w z$ p5 r0 T
combined appliances where the heating elements are supplied via a switch mode power
, F* {8 e8 g- ?( }, p Y, u8 |5 @supply are carried out at a voltage corresponding to the specified power input.! L1 q2 T* w% |* ?2 _! ?* V
When a power input greater than the rated power input is specified, the factor for multiplying
( P4 ]9 d7 @. p! Nthe 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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