我段使用的DFH<21>型内燃机车,其风泵二级起动控制电路(图1)从原理上讲是能满足保证条件的。但是,该电路经运用后发现存在有缺点。这就是电空阀19F的线圈从乘务员接班后闭合蓄电池、总控及各脱扣开关起直到下班止,其中除了风泵在二级运用工况(不到一分钟时间)外,有80％以上的时间均处于通电状态。由焦耳—楞次定律可知,它将 DFH <21> Diesel locomotive used in my paragraph, the second stage start-up control circuit of the air pump (Figure 1) can basically meet the guarantee conditions in principle. However, this circuit has been found to have disadvantages after it has been used. This is the solenoid valve 19F coil from the flight attendant after the closure of the battery, the total control and the trip switch until the stop only, in addition to the use of wind pumps in the second level (less than a minute), more than 80% Of the time in the power state. By Joule - Lenz’s law we can see that it will