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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 :- f- j' }7 }0 u) q4 t
在做测试时会碰到下面问题:9 Z7 P- T4 l2 c+ o8 ^
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?6 P; E( \- o) |
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?$ R6 o- v ~0 {3 D7 c' n4 F3 g
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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{& M/ s4 D! k. ^; a以下引用於:Test Method for Calculating the Energy Efficiency of Single-Voltage External Ac-Dc and Ac-Ac Power Supplies% U0 U2 j) d" n* V5 d" r
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d. Testing Sequence
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I* r+ M0 v* r6 T3 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. : y+ z8 y7 C6 l/ c( m9 C! R
4 W6 W/ { ~1 WAfter 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. 4 m/ H$ J# U9 g" [ g8 T6 ~9 g9 i
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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." |$ B u Y9 d" E9 p" D
% c/ f* g7 j- T' B1、 你的做法是錯誤的,請參考上面的紅色字體部分。
2 R6 B D, j5 ~: _8 v& v# Z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。9 p& _! g: X1 j: l3 P" c; I0 c
# O9 }! C: w- i2、 我個人傾向於取0.35W,因為0.66W是一個假像。 X5 q. g2 r" J, ]4 F1 N
}+ j- P. _0 B3、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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