This paper analyses the characteristics, efficiency and harmonic of four kinds of power circuits for SCR-cascade control used in textile mill ventilators.

本文分析了目前纺织厂通风机可控硅串级调速四种主电路方案的特点、效率和谐波等情况。

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The hospital had no power, no water, food was running out and nurses were bagging patients by hand because ventilators didn't work.

CNN: vert.sandbag.drop.pool.jpg