Based on the theory of commutation in DC machines, this paper describes a numerical analysis method for analysis of the commutation spark.

本文根据直流电机换向理论，给出了一种分析直流电机换向火花的方法。

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The field circuit and the armature circuit can be interconnected in various ways to provide a wide variety of performance characteristics - an outstanding advantage of DC machines.

励磁绕组和电枢电路有各种接法，因而有不同的性能，这是直流电动机的显著优点。

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The outstanding advantages of DC machines arise from the wide variety of operating characteristics which can be obtained by selection of the method of excitation of the field windings.

直流电机的突出优点是通过选择磁场绕组不同的励磁方法，可以获得变化范围很大的运行特性。

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After two years, my teaching contracts ended, so I said hasta luego to my life on the Iberian Peninsula and moved back in with my parents to work a nine-to-five desk job in Washington DC, dealing with financial reviews, company deadlines, terrible co-workers and fax machines that never worked.

BBC: How I quit my job to travel: The blogger