The U.S. customary system of measurement is commonly referred to as the metric system.
Answer the following statement true (T) or false (F)
False
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A(n) ____ circuit interrupter is a device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected.
a. extended b. overload c. arc-fault d. closed
An open case is more efficient than a closed case.
Answer the following statement true (T) or false (F)
Describe the four-stroke cycle.
What will be an ideal response?
A dc, separately excited motor is driven by a full-wave, SCR, ac/dc converter. The voltage on the ac side is 120 V (rms). The field constant of the motor K? = 3 Vs. At a load torque of 300 Nm and triggering angle of 40o , the motor speed is 100 rpm, and the armature current is continuous.
a. The polarities of the terminal voltage of the motor (armature voltage) are reversed, and the triggering angle is simultaneously changed. Assume that the load torque is also reversed and is equal to 300 Nm. Calculate the triggering angle that stops the motor and keeps it at the holding position. Assume that the current is still continuous. b. Sketch the speed-torque characteristics and indicate the steady state operating points before and after polarity reversal.