问题 问答题 简答题

对矿用隔爆磁力起动器有哪些基本要求?

答案

参考答案:一般有如下几项要求:1)外壳必须满足矿用隔爆设备所规定的各项要求。2)主接触器不仅能多次接通、断开有载动力负荷,而且要求能切断短路电流(在一定范围程度内),有足够的机械寿命和电气寿命,以适应频繁起动要求。3)有较完善的保护装置:一般应有过负荷、短路、欠压、漏电闭锁等保护装置;有些电压较高,控制大容量电动机起动的还没有过电压、断相,或有选择性漏电保护装置。4)隔离换向开关与前门之间有可靠的机械闭锁装置,以保证在前门打开时,控制单元不带电,磁力起动器不能起动。5)电气线路应满足相应的电气间隙以及爬电距离的要求。6)能实现就地控制、远方控制、联锁控制和顺序控制方式。7)对控制系统除要求动作可靠、操作方便外,为安全起见,还要求采用安全电压(36V以下电压)型或本质安全型控制电路。

单项选择题

(B)

When first entered, Vanak Restaurant does not look like much of a restaurant, but once the pleasant smells of kabob(烤肉串)hit the senses, you are incapable of calling it anything less.

Owned by a local couple, this Persian restaurant has an inviting, homelike atmosphere that many restaurants lack.

The space is small with only a few dining tables and nearly no decoration, but the environment is truly charming.

Lying in a hardly noticeable steed corner, the restaurant still attracts all customers, especially those experienced in the delights of Middle Easter cooking.

A common sight is that of old Persian men sitting in the corner talking loudly about world topics, watching news events on TV, drinking a black tea known as Persian chai, and reading local Persian newspapers all the while trying to finish off their plates piled with food.

The variety of food at the restaurant is limited, but the amount of each dish is fairly large. Most of the meals can serve two people and are under $10, so not only is it affordable but practical as well.

The food especially appeals to health-conscious eaters because each dish is very healthy, made with limited fat and oil and served straight off the grill.

The main dish that the restaurant is popular for its kabobs, which are different styles of grilled meat.

One delicious and extremely healthy dish is the Joojeh Kabob, which is made of grilled chicken pieces served with either rice or bread. Another great kabob is the Chelo Kabob, a kabob consisting of grilled beef.

Although the restaurant is small, the atmosphere and the food is delicious. It is a place that should not be overlooked.

The food of the restaurant()

A. is served in small amounts

B. is rather expensive

C. is rich in variety

D. is very healthy

单项选择题