Test VIII - cumulative test (0)

Test VIII - cumulative test
by Piigli, Mets, Parker , Kauler
“Top delusion ” question / answers are red.
Test I
The induction machines are associated with the names of Dolivo - Dobrovolsky, Tesla.
The synchronous machines are associated with the name of Ferraris.
The DC machines are associated with the names of Jacobi and Henry .
The electromagnetic torque is born in air gap.
The torque is proportional to the current in dc motor .
Which equations are correct ? P = sW; oomega = tuletis fii’st
The angular frequency is 2*pi()*n / 60 ja 2*pi()f
The motor torque is equal to TL + J * oomega tuletis aja järgi
The inductor supplies the motor with flux .
The leading companies in the world market of electrical drive engineering are: Mitsubishi .
The energy balance is described by energy conservation law.
The armature supplies the motor with current.
The cheapest and the most reliable is induction motor.
The torque production is the result of interaction of current - flux.
The mechanical torque as compared to the electromechanical torque is  ??
The source of the magnetic flux of the motor is DC or permanent magnet.
The most suitable for the speed control is synchronous servo motor.
Efficiency of the electrical drive is the power ratio of load to supply .
Electromagnetic efficiency is measured in tesla.
One of the first eletrical motors has been built by Jacobi.
The best electrical drive has efficiency very high.
Who studied electromagnetic field ? Lomonosov/ Gilbert /Coulomb/Oersted??
What kinds of disturbances affect the electrical drive behavior ?
The current is the motor response, not the disturbance. The external disturbances are the supply voltage and the counter -torque.
Which components comprise the electrical drive? Which of them are mandatory and which are optional ?
The mains and the actuator (driven machine ) are not the drive components. The drive includes, by all means , the motor and controller, and may additionally incorporate the power converter and gear .
Test II
In the very accurate drive, the over-speed is 1..10%.
If the required speed would rise, the mechanical time constant do not change .
Time constants are measured by ms, s, hours.
The mechanical time constant is high if Td is low.
In the case of quick action - ??
The characteristics of the rigid drive is rigid.
The standard supply grid has the oscillation period of 20 ms.
In the steady -state mode, the drive has ripples, pulsations.
The rigidity of the high-efficient electrical drives is high.
The following characteristics are the electromechanical ones: speed-current.
The following characteristics are the mechanical ones: speed-torque.
The multi -quadrant operation is typical for car.
At the very low speed the torque is less than rated.
In the reversing operation, the following variables change their sign : pakuks torque ja speed
The speed range of the high - efficient electrical drives is high.
In the generator mode, the motor brakes.
The counter-torque of the hoist is active/reactive/inductive (pakuks active)
The friction torque is passive /reactive/inductive (pakuks reactive)
In the case of high quick action tauT is short ja taue is short
In the case of low quick action the overtorque is 0.
The overshot of the stable system - no overshoot.
The usual time response processes are step (äkki peaks miskit veel olema?)
In the accurate drives, the accuracy range is small.
How does the drive accuracy depend on the speed range? the speed rigidity? the overload capacity?
The higher , the better.
Why is the torque restricted at the very low speed?
In the range of the low speeds due to the cooling deterioration, the load derating is recommended up to 15…30 %.
What quadrants of the mechanical characteristics are the most significant for the reversing operation? Which variables change their sign in the reversing operation?
The reversing drive operates within two or four quadrants jumping from the first to the fourth or from the third to the second quadrants.
Test III
Select the motors with the slip rings: wound -rotor synchronous
Select the motors with permanent magnet excitation: separate excited DC, ??
Select the natural reference frames : L1, L2, L3
Select the stationary reference frames: alfa, beeta
If the stator field frequency is 100, what will be the synchronous frequency of the 2-pole motor? 100
Select the correct frequency equilibrium: w1 = w2 + w12; w12 = w1 - w2 (w- oomega)
The mutual motion of the stator and rotor windings result in ??
If the stator field frequency is 100, what will be the slip frequency of the loaded induction motor?