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5.12 For heating appliances and combined appliances, when it is specified that the. H9 D5 e% ?, v5 F7 ~2 N
appliance has to operate at a power input multiplied by a factor, this applies only to heating
) O+ G6 g% G1 ~# s' Lelements without appreciable positive temperature coefficient of resistance.
: y1 Z; }# M! ]4 M; iFor heating elements with appreciable positive temperature coefficient of resistance, other than
) n. y6 ~) p0 M5 tPTC heating elements, the supply voltage is determined by supplying the appliance at rated7 V, i% ?5 t$ b: F$ X% i4 C X
voltage until the heating element reaches its operating temperature. The supply voltage is then5 @4 t7 Z0 z; k* A! t4 H# M3 z
Copyright International Electrotechnical Commission$ e& x: b7 }1 v( o
rapidly increased to the value necessary to give the power input required for the relevant test,
8 ~1 _4 ?& D& {this value of the supply voltage being maintained throughout the test.
/ \) }4 |7 G( x: b: v6 D ?5 g% J6 x4 Z UNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input8 B; ^5 \& x% d; z8 Z d
of the appliance in cold condition differs by more than 25 % from the power input at operating temperature.! ?0 d% s- i, i! n) S& X
5.13 The tests for appliances with PTC heating elements and for heating appliances and v& }3 ?9 i' R# i2 @
combined appliances where the heating elements are supplied via a switch mode power6 @8 S5 F: h4 l! t1 ?
supply are carried out at a voltage corresponding to the specified power input.
6 H* E4 C5 M% I( B: f! b5 JWhen a power input greater than the rated power input is specified, the factor for multiplying% Y* W3 y: D# T6 J
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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