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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 :0 @2 ~- X5 }9 z% r
在做测试时会碰到下面问题:
) h: V2 v+ a: a* i* E, r) Z1、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? u7 b8 C. t+ \2 d* Q
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?/ e* Q. u% w4 m% s0 k, T
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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8 x- R. P5 X" d- a, M4 h4 g9 ?. D. C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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: H8 l3 W# f3 qd. Testing Sequence " S2 R/ ]4 ] y2 f
9 }: r+ H( }% ?0 e) ~( A, mAs 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.
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% \# d# [! U' @; w2 s9 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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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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1 A! g, P2 @4 v# H0 bIf 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。, U/ `$ R; t* v% m8 N, r
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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. Y* v$ `1 }. \# f' L2、 我個人傾向於取0.35W,因為0.66W是一個假像。2 o7 N- K" Z$ g
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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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6 F8 _7 z7 w h2 \" C# k![](static/image/smiley/pw_default/mrgreen.gif) |
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