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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 :
. b7 s- T4 z7 X在做测试时会碰到下面问题:
8 T$ M: M4 U0 b. L, x* V( ]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?, V0 G2 r5 @+ r* |: A
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?/ b; M: }6 P; w/ a6 c
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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* s( c* Y* y- F M/ V$ g4 @3 H6 y以下引用於:Test Method for Calculating the Energy Efficiency of Single-Voltage External Ac-Dc and Ac-Ac Power Supplies8 r# ]. c, l$ Q. h# l* @7 |6 h
" I8 {& k/ M* R0 D K$ j0 Vd. 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. 9 E7 H f. _) Q: a- A* b
/ o, v- b0 o+ x* Y+ `/ xAfter 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. X2 Q& \! m3 A7 K
4 @. A1 ^5 d* { h! w$ GNote that only one warm-up period of 30 minutes is required for each UUT at the beginning of the test procedure. & e$ m$ `* F% _0 b$ a+ w; z
4 z" |" |% N n; L, vIf 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.# r: a" g: _8 f6 i0 M; G% X
L. B2 A2 W! M4 g6 Z9 i1、 你的做法是錯誤的,請參考上面的紅色字體部分。/ W6 L S: t! R9 g9 K" X, x S
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。* G+ R' ?) \+ R) M6 l r
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2、 我個人傾向於取0.35W,因為0.66W是一個假像。
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4 J9 L: [* @$ }: Y" U$ S3、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。
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