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5.12 For heating appliances and combined appliances, when it is specified that the
. Q( Q/ {. O" u7 T5 O& [+ v. Mappliance has to operate at a power input multiplied by a factor, this applies only to heating- V3 U9 K5 l6 w( J3 A/ k5 n
elements without appreciable positive temperature coefficient of resistance.
- U: i" B- F/ z8 p; w3 I. X x7 e8 }For heating elements with appreciable positive temperature coefficient of resistance, other than
: q% Z- }- n" S' ~PTC heating elements, the supply voltage is determined by supplying the appliance at rated
1 M2 n k$ K! c9 l$ ^2 U: d- v. yvoltage until the heating element reaches its operating temperature. The supply voltage is then
' _- z; v) p, |- l; t: SCopyright International Electrotechnical Commission
. O- Z# k1 {/ }" j8 U/ S# @rapidly increased to the value necessary to give the power input required for the relevant test,
; a1 Y' ~$ u! Kthis value of the supply voltage being maintained throughout the test.7 m, Q% }- {: ]5 ]" f
NOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input' Z8 {; J8 ~ W, u8 S- \5 ?& f( x
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.0 H# O" y' i u0 c$ l) }
5.13 The tests for appliances with PTC heating elements and for heating appliances and) D' \- \2 r, s
combined appliances where the heating elements are supplied via a switch mode power: M8 J' O) q( e/ a- {
supply are carried out at a voltage corresponding to the specified power input.# h7 I8 R ~7 y, w$ h
When a power input greater than the rated power input is specified, the factor for multiplying/ n% }! I2 g; Z( [+ l# [2 {1 v
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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