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5.12 For heating appliances and combined appliances, when it is specified that the
+ n. M0 w) i: Q; E' kappliance has to operate at a power input multiplied by a factor, this applies only to heating7 a- } @" P7 _2 H+ F: S
elements without appreciable positive temperature coefficient of resistance.
* q- z2 l) O1 E4 z# h$ u' B( rFor heating elements with appreciable positive temperature coefficient of resistance, other than9 }9 A5 f5 n- ~6 Y
PTC heating elements, the supply voltage is determined by supplying the appliance at rated
3 S; v" }: r" hvoltage until the heating element reaches its operating temperature. The supply voltage is then
! c4 E" J( F% {9 ]/ L2 ?! ACopyright International Electrotechnical Commission* ^6 r& V! F) Q8 ^+ x3 E$ b
rapidly increased to the value necessary to give the power input required for the relevant test,: |" G O1 R5 ?( a
this value of the supply voltage being maintained throughout the test.
/ \" l9 i$ q) dNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
6 C+ Y& F( p( Vof the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
- X5 P+ U I, f5.13 The tests for appliances with PTC heating elements and for heating appliances and3 z6 i2 F2 R& r' N! T
combined appliances where the heating elements are supplied via a switch mode power, Y) @7 L* y z6 U% Q2 K" h: x
supply are carried out at a voltage corresponding to the specified power input.: c( g+ [0 ?2 j& r0 e
When a power input greater than the rated power input is specified, the factor for multiplying
9 I# \+ n: F, @4 P4 ^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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