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5.12 For heating appliances and combined appliances, when it is specified that the
# O9 `' F% H6 i4 i) Nappliance has to operate at a power input multiplied by a factor, this applies only to heating! `& F( L- a" s& \6 Z1 P- m& d
elements without appreciable positive temperature coefficient of resistance.+ P6 U) J7 x" D* ` r
For heating elements with appreciable positive temperature coefficient of resistance, other than3 }; q2 T' N& B, `5 f1 P* d
PTC heating elements, the supply voltage is determined by supplying the appliance at rated
3 A- Z0 U. T3 y" Y, |0 u: `voltage until the heating element reaches its operating temperature. The supply voltage is then
% S5 D" f) U2 O# v) D, z2 f; \6 gCopyright International Electrotechnical Commission4 O/ u/ b& r5 R# u$ _: W
rapidly increased to the value necessary to give the power input required for the relevant test,, B$ K4 f& P- a4 K6 B& _
this value of the supply voltage being maintained throughout the test.* {+ c8 e7 k+ p* y$ ] i" [$ j- p* b4 F
NOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input' ?; L. h" A6 J! C8 T. |
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.8 x% c, `; ^1 O8 l
5.13 The tests for appliances with PTC heating elements and for heating appliances and2 z6 `$ U1 q3 G+ }' P
combined appliances where the heating elements are supplied via a switch mode power
" k2 D/ h* u4 k2 Osupply are carried out at a voltage corresponding to the specified power input.& w! [* @( S" N& J
When a power input greater than the rated power input is specified, the factor for multiplying F! u1 a' {4 } H8 A0 v H
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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