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5.12 For heating appliances and combined appliances, when it is specified that the9 {3 Q! |4 \% l( I: w, X; K. S
appliance has to operate at a power input multiplied by a factor, this applies only to heating
' r, b6 X8 J! x8 delements without appreciable positive temperature coefficient of resistance.0 z, r. w. \# k: N
For heating elements with appreciable positive temperature coefficient of resistance, other than5 I8 d/ G. u5 q: w
PTC heating elements, the supply voltage is determined by supplying the appliance at rated C( I# n0 D) f" a% H
voltage until the heating element reaches its operating temperature. The supply voltage is then
2 X7 K$ ^6 |6 f9 M" B; i- @Copyright International Electrotechnical Commission
. X2 E2 b$ w; m# l( Lrapidly increased to the value necessary to give the power input required for the relevant test,6 }2 i3 m& n1 G- K& Y
this value of the supply voltage being maintained throughout the test.+ j+ S5 n# E& v( L! B4 ]
NOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
- J: F a$ V) l, E- sof the appliance in cold condition differs by more than 25 % from the power input at operating temperature.5 Q% X, q7 y5 H$ d0 p5 ?$ ]: N8 }
5.13 The tests for appliances with PTC heating elements and for heating appliances and4 F( D- M& ]# y2 f* F6 y& V
combined appliances where the heating elements are supplied via a switch mode power
+ A0 m! ~/ b: v% i! Osupply are carried out at a voltage corresponding to the specified power input.9 O( d! E- ]+ E1 O d9 Z; u
When a power input greater than the rated power input is specified, the factor for multiplying
$ x0 v Z% N" ~7 Othe 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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