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5.12 For heating appliances and combined appliances, when it is specified that the
, r/ W0 Q' g6 x% xappliance has to operate at a power input multiplied by a factor, this applies only to heating
0 E. |' [6 `& v' delements without appreciable positive temperature coefficient of resistance.8 }5 m V7 G# Z5 h' Q$ U
For heating elements with appreciable positive temperature coefficient of resistance, other than. M* K$ Y/ e) W; b7 Q
PTC heating elements, the supply voltage is determined by supplying the appliance at rated. i6 s3 f5 c6 ~( {+ _
voltage until the heating element reaches its operating temperature. The supply voltage is then. k) \) g" T! q
Copyright International Electrotechnical Commission
2 G! q d7 j0 b% h9 }rapidly increased to the value necessary to give the power input required for the relevant test,
, _( M* Q6 P, l4 Qthis value of the supply voltage being maintained throughout the test.
6 W3 h4 u" L2 s& Y7 O/ M( {. O( tNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input+ h8 U9 m/ X* f0 G% }
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
5 Q3 i0 x& b- }6 Z/ @5 C5.13 The tests for appliances with PTC heating elements and for heating appliances and4 r! k2 r7 O, P# U+ L$ ]% x3 @
combined appliances where the heating elements are supplied via a switch mode power8 \5 S2 G* }6 b/ Z3 ?
supply are carried out at a voltage corresponding to the specified power input.' t. z+ J! y4 s; v+ k3 d8 v
When a power input greater than the rated power input is specified, the factor for multiplying: Z0 K: ?( S, q
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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