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5.12 For heating appliances and combined appliances, when it is specified that the9 C7 V) g+ x: Q4 |0 h/ S
appliance has to operate at a power input multiplied by a factor, this applies only to heating
4 k; Y7 N; v8 {elements without appreciable positive temperature coefficient of resistance.& e# F. G5 V$ [ G- w% e% |1 x3 C
For heating elements with appreciable positive temperature coefficient of resistance, other than% S0 }' U* K9 Y. K9 L0 L) J, W
PTC heating elements, the supply voltage is determined by supplying the appliance at rated
4 S3 z4 |. I7 H' u% ?8 Rvoltage until the heating element reaches its operating temperature. The supply voltage is then. b9 x* z/ m0 Y3 N- }1 a# r+ n' `
Copyright International Electrotechnical Commission
( f* W$ K, \! s' u) krapidly increased to the value necessary to give the power input required for the relevant test,
" m- L+ m) v$ T0 ~this value of the supply voltage being maintained throughout the test.
/ S$ _4 i% N( I# _2 R+ ANOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
" n7 `6 [8 F/ L/ M6 N& v! V! yof the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
6 F, p3 g( _- n9 c O5.13 The tests for appliances with PTC heating elements and for heating appliances and
/ a5 s$ D& S) @( m6 r) r5 N2 |combined appliances where the heating elements are supplied via a switch mode power
+ N! V# N; t0 k8 fsupply are carried out at a voltage corresponding to the specified power input.5 g4 C0 _8 q7 Y8 C
When a power input greater than the rated power input is specified, the factor for multiplying$ {+ V' \8 n4 k5 k
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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