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引用第0楼yrj109于2007-08-01 19:41发表的 关于CEC test 困惑 :3 d; a- ~7 I+ a& r) Q( Y; ]
在做测试时会碰到下面问题:& [& q* v3 x" E, d! f" A
1、有些产品在做测试时,输入功率会跳动(可以确定是产品造成的),此时输入功率这么取?本人是取最大值的,是否正确?% S8 Z: |( W1 a) H4 G( N, c
2、做最后一项空载输入功率时(控标准顺序),有些产品在热态下会很大(如0.66W),但当产品完成冷下来后(大概一小时)输入轴功率又会变小(如0.35W). 取0.35W 是否正确?1 v) t! [+ h( s+ P0 O7 X
3、THD 值按标准计算公式得出会是在100%--300% 之间,标准里所提到的 THD值 是如何定的?
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9 C4 P% R# b3 L3 q以下引用於:Test Method for Calculating the Energy Efficiency of Single-Voltage External Ac-Dc and Ac-Ac Power Supplies/ o6 `3 ]0 T3 ]0 H% U( a# O
) {6 u) ^: u hd. Testing Sequence
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As noted in IEC 62301, instantaneous measurements are appropriate when power readings are stable in a particular load condition. The UUT shall be operated at 100% of nameplate current output for at least 30 minutes immediately prior to conducting efficiency measurements. $ c& Y2 W z( _7 Y6 B+ s+ P
2 I# w% k r& l, `After this warm-up period, the technician shall monitor ac input power for a period of 5 minutes to assess the stability of the UUT. If the power level does not drift by more than 5% from the maximum value observed, the UUT can be considered stable and the measurements can be recorded at the end of the 5 minute period. Subsequent load conditions (see below) can then be measured under the same 5 minute stability guidelines.
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Note that only one warm-up period of 30 minutes is required for each UUT at the beginning of the test procedure.
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If ac input power is not stable over a 5 minute period, the technician shall follow the guidelines established by IEC 62301 for measuring average power or accumulated energy over time for both ac input and dc output.6 k2 Q4 X$ y! U4 S! R3 C! k, J
P# j: i8 h& l% V b8 W6 k1、 你的做法是錯誤的,請參考上面的紅色字體部分。
7 h \1 N# P3 o9 {( n. M如果在測試時,输入功率会跳动,此時應按IEC 62301,取得5分鐘內的平均功率。
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; ^. _2 f1 r: x3 O) M) m) {* g2、 我個人傾向於取0.35W,因為0.66W是一個假像。8 C- c7 Y( G3 [( p6 X+ E
% |) \) Z2 A. C% S* ?. T3、THD的計算方法請參考圖片的公式。說實話,我對THD也是不太明白。 引用Mikesu兄的說明給你參考一下:“THD 一般可用測 EN 61000-3-2 (電源諧波量測設備) 進行檢測. 或是高階的電力分析儀”。另外,CEC並未限制THD的數值,只需在報告列出數據即可。4 z' X3 D4 O1 F2 U2 r# ]$ @
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