Individual work #3 What stepper motor has to offer in the field of engineering?

A stepper motor cannot be bench-checked directly from a power source. Why?

When electrical command pulses are applied, the shaft of the stepper motor rotates in discrete increments; unlike other motors which rotate continuously. Every revolution is divided into number of steps.
А stepper motor cannot be bench-checked directly from a power source because this motor requires pulse type input rather than continuous input. The amount of rotation is directly proportional to the number of pulse. A 1-degree-per-step motor will require 360 pulses to move through one revolution. The bench-checked power source consist of continuous supply of voltage. Hence stepper motor cannot be bench-checked directly form a power source.
Thus, the reason for the stepper motor which cannot be bench-checked directly from a power source is explained.

7. 
   What is meant by detent torque, and in what type of motors does detent torque occur?
   

One feature of stepper motors that differentiates them from other motor types — particularly servo motors — is that they exhibit holding torque.
Of the three types of stepper motors — variable reluctance, permanent magnet, and hybrid — only variable reluctance motors do not exhibit detent torque.
This means that when the windings are energized but the rotor is stationary, the motor can hold the load in place. But a stepper motor can also hold a load in place when there is no current applied to the windings (for example, in a power-off condition). This is commonly known as the detent torque or residual torque.
Stated another way, detent torque is the amount of torque the motor produces when the windings are not energized. The effect of detent torque can be felt when moving the motor shaft by hand, in the form of torque pulsations or cogging.

8. 
   What is meant by the ‘holding torque’ of a stepping motor?
   

A stepper motor’s holding torque is the amount of torque needed in order to move the motor one full step when the windings are energized but the rotor is stationary. Holding torque is one of the primary benefits that stepper motors offer versus servo motors, making stepper designs a good choice for cases where a load needs to be held in place.
Holding torque is typically higher than running torque, and is limited primarily by the maximum current the motor can withstand.

9. 
   Find the step angle of the following stepping motors: (a) 3-phase, VR, 12 stator teeth and 8 rotor teeth; (b) 3-phase, VR, three-stack, 16 rotor teeth; (c) 4-phase unipolar, hybrid, 50 rotor teeth.
   

10. 
    Named two methods of Damping Rotor Oscillations and explain one method of damping. There are two basic methods of damping rotor angle oscillations. The first one is to adjust transmission capability between the oscillating generators. This is either done with a series or shunt element. Basically one tries to strengthen the transmission system when the rotors are diverging (going apart) and weaken the system when they are coming together.
    

11.