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5.12 For heating appliances and combined appliances, when it is specified that the
( ~3 A: ?7 V4 Y' yappliance has to operate at a power input multiplied by a factor, this applies only to heating
# t9 K6 l( ?# x7 c6 K: q& oelements without appreciable positive temperature coefficient of resistance.& T9 a- {. J; ~
For heating elements with appreciable positive temperature coefficient of resistance, other than
8 v9 x; C8 I* }, Z5 w- i. ^PTC heating elements, the supply voltage is determined by supplying the appliance at rated
4 H8 y( I* C. @2 W/ Lvoltage until the heating element reaches its operating temperature. The supply voltage is then0 }$ x( ]7 n; g$ Z( Y M
Copyright International Electrotechnical Commission
1 t. q7 g* y' ~rapidly increased to the value necessary to give the power input required for the relevant test,9 e: s F4 J8 n' T7 n" \0 d: U; J* [
this value of the supply voltage being maintained throughout the test.
) D* ^, d, i- N: rNOTE In general, the temperature coefficient is considered to be appreciable if, at rated voltage, the power input
/ k! a" V6 ?) nof the appliance in cold condition differs by more than 25 % from the power input at operating temperature.
2 w+ B4 V6 ~7 ?" ]/ X% N5.13 The tests for appliances with PTC heating elements and for heating appliances and
0 l) F% Y9 R! N" `combined appliances where the heating elements are supplied via a switch mode power
! E% x' s3 \* V4 W" f% |supply are carried out at a voltage corresponding to the specified power input.
" m# Z3 U, E. mWhen a power input greater than the rated power input is specified, the factor for multiplying
) [' V6 S8 D; q$ A! o: Nthe 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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