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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 :
& k, o0 q0 f6 R- Q$ @- ?在做测试时会碰到下面问题:
2 E8 V' g" ]( H1、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?
+ J; u7 k( N" z7 [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?, H0 D+ P* y& T9 r
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? . w# F: [2 j* m8 G* _+ ?
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以下引用於:Test Method for Calculating the Energy Efficiency of Single-Voltage External Ac-Dc and Ac-Ac Power Supplies
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d. Testing Sequence 9 w5 b/ o# Q4 h" |$ p$ a
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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. 1 F% Q$ l+ G$ k% C3 h0 s( a- U
4 E$ `( L7 w4 qAfter 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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+ Q" }- A1 {" q" i4 ~9 zNote 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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" A) h) k) I# \, g: t; c wIf 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.
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1、 你的做法是錯誤的,請參考上面的紅色字體部分。
) R# c' K* ~8 w- z ]4 d8 c3 ~4 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。6 o. p$ I0 _6 \8 Z
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2、 我個人傾向於取0.35W,因為0.66W是一個假像。" v! Y9 r8 B5 d* F+ P( K
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3、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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