步进电机开环进给系统的进给速度取决于()。
A. 指令脉冲频率f
B. 控制电流的大小
C. 指令脉冲的个数
D. 控制电压的大小
寄达地为三区的国内特快专递邮件一件,重()克,应收资费47元。
A. 800
B. 1000
C. 1500
D. 2000
Diesel engines driving alternators operating in parallel must maintain set frequency regardless of load changesThe governor characteristic used to accomplish this is known as ()
A. actuation
B. sensitivity
C. compensation
D. thrust shaft