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5.12 For heating appliances and combined appliances, when it is specified that the
9 l6 v* `5 d& P1 |5 X9 u& Sappliance has to operate at a power input multiplied by a factor, this applies only to heating) B* a9 n! D' @# f: J a2 x% _4 ?
elements without appreciable positive temperature coefficient of resistance.
5 q$ ^( i. D, c Y3 P7 V" e" A6 n/ }9 bFor heating elements with appreciable positive temperature coefficient of resistance, other than5 V; V( l- c7 H; g( z+ v
PTC heating elements, the supply voltage is determined by supplying the appliance at rated0 q# H6 z+ G @0 N5 o- X
voltage until the heating element reaches its operating temperature. The supply voltage is then
% A# t9 K' S7 U3 qCopyright International Electrotechnical Commission
6 ^' G! ?% A2 q7 k; @: ^- T7 Vrapidly increased to the value necessary to give the power input required for the relevant test,/ E$ K T( Z. u; f8 b
this value of the supply voltage being maintained throughout the test.% U8 }7 W8 a5 t3 W& j
NOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input- x. _, O8 Z& i: Y W( H- A
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
! G0 T% l, S. ~5.13 The tests for appliances with PTC heating elements and for heating appliances and+ N9 j2 X( C( |
combined appliances where the heating elements are supplied via a switch mode power6 S" l/ T \) K% s, O0 p
supply are carried out at a voltage corresponding to the specified power input.
5 p$ l2 _! T t) f7 L0 T6 I& w% WWhen a power input greater than the rated power input is specified, the factor for multiplying* u) Q" {) o+ ]# n
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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