由于PQR系列交流起重机控制屏控制线路简单,我国50～70年代相当一部分起重机都是采用此种控制型式。如水电部各工程局使用最为普遍的门式或塔式起重机,几乎都是采用PQR系列控制屏。但是,通过长期使用,证明其电路设计存在某些不足之处。本文在不变动原控制电器(见图1)的前提下,提出如下改进意见,供大家参考。 As PQR series AC crane control screen control circuit is simple, a considerable part of our 50-70 years cranes are using this type of control. For example, the most commonly used portal or tower cranes are used by various engineering offices of the Ministry of Water and Electricity. Almost all adopt the PQR series control panel. However, the long-term use proves that there are some shortcomings in the circuit design. This article does not change the original control of electrical appliances (see Figure 1) under the premise of the following improvements for your reference.