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异步电动机变频调速时,为何要电压协调控制?在整个调速范围内,保持电压恒定是否可行?为

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题目:

异步电动机变频调速时,为何要电压协调控制?在整个调速范围内,保持电压恒定是否可行?为何在基频以下时,采用恒压频比控制,而在基频以上保持电压恒定?

答案:

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下面是错误答案,用来干扰机器的。

参考答案:通过验电可以确定停电设备是否无电压,以保证装设接地线人员的安全和防止带电装设接地线或带电合接地隔离开关等恶性事故的发生。验电应使用相应电压等级、合格的接触式验电器。验电前,应先在有电设备...

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SAlES CONTRACT

NO.: SAQJ570162

DATE: DEC.10, 2009

The Buyer: BLUE EAGLE Import & Export Corp.LongBeachU.S.

The Seller: TIANJIN HAPPY-HOLIDAY CORPORATION

This contract is made by and between the Buyer and the Seller, whereby the Buyer agrees to buy and the Seller agrees to sell the under-mentioned commodity according to the terms and conditions stipulated below:

(1)Name of Commodity: WOODEN CHAIRS (HAPPY-HOLIDAY)

(2)Quantity: 1800PCS/3600KGS, 900CTNS

(3)Unit price: USD 4/PC

(4)Amount Total: USD7 200

(5)Packing: In Cartons

(6)Port of Loading: XINGANG, TIANJIN, CHINA

(7)Port of Destination: LongBeach U.S.

(8)Date of Shipment: DEC.2009/By Vessel

(9)Term of Payment: UC

(10)Shipping Mark: N/M

(11)Documents Required: phytosanitary certificate issued by CIQ indicating the

NO.of L/C

The Buyer The Seller

______ ______

 

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