Why Hopkinson test is performed?
Hopkinson’s Test is another useful method of testing the efficiency of a DC machine. It is a full load test and it requires two identical machines which are coupled to each other.
What for Hopkinson test is also called regenerative test?
Hopkinson’s Test is also known as Regenerative Test, Back to Back and Heat Run Test. In Hopkinson Test, two identical shunt machines are required which are coupled both mechanically and electrically in parallel. One is acting as a motor and another one as a generator.
Why Swinburne’s test is called as indirect test?
Swinburne’s Test is an indirect method of testing of DC machines. In this method, the losses are measured separately and the efficiency at any desired load is predetermined. Machines are tested for finding out losses, efficiency and temperature rise.
Which of the following is regenerative method of testing?
Hopkinson’s test is a regenerative test. Explanation: Hopkinson’s test is a regenerative test, because the power drawn from the mains is only that needed to supply losses.
What is Ward Leonard method?
Ward Leonard method of speed control is used for controlling the speed of a DC motor. It is a basic armature control method. This control system is consisting of a DC motor M1 and powered by a DC generator G. In this method the speed of the DC motor (M1) is controlled by applying variable voltage across its armature.
What is rotational loss in dc machine?
Because mechanial losses and magnetic losses are approximately proportional to the motor’s rotational speed, they are often taken together and referred to as rotational losses. Various types of losses, including rotational losses, reduce motor efficiency.
What are losses in DC machine?
The losses in the dc machine are mainly separated into five categories like electrical/copper, magnetic/core/iron, brush, mechanical, and stray.
Why Swinburne’s test is economical?
This test helps to pre-determine the efficiency at any load with constant flux. The most important advantage of Swinburne’s test is, the motor can be used as a generator and no-load losses can be measured separately. This test is very simple, and economical because it operates in no-load power input.
What will happen if field current of generator in Hopkinson test is increased?
Explanation: If field current through generator is increased, back emf of generator will increase thus it’ll become greater than back emf of a motor, so to compensate this effect armature current in generator will increase thus, motor armature current will also increase.
Why voltage drop is so sharp in case of shunt generator?
In actual use, the output voltage in a dc shunt-wound generator varies inversely as load current varies. The output voltage decreases as load current increases because the voltage drop across the armature resistance increases (E = IR).
What is flux per pole?
Explanation: Flux is defined as flux density for a given surface area. Here, Surface area can be calculated and multiplied with B to give the value of flux. Flux= 2πr*l*B. now, for calculating flux per pole, divide it by P=4. So, Flux per pole after substituting all values is equal to 0.0188 Wb.
What is Hopkinson’s test?
For this process of back to back driving the motor and the generator, Hopkinson’s test is also called back-to-back test or regenerative test. If there are no losses in the machine, then no external power supply would have needed.
How do you determine the concentration of a solution in titration?
In volumetric analysis, the concentration of a solution is determined by allowing a known volume of the solution to react, quantitatively with another solution of known concentration. Question.15. What is titration?
Why does the volume of titration flask increase during rinsing?
This is because during rinsing some liquid will remain sticking to the titration flask there-fore the pipetted volume taken in the titration flask will increase. 11. What are primary and secondary standard substances? Ans.
Is Hopkinson’s test regenerative test?
Clarification: Hopkinson’s test is a regenerative test, because the power drawn from the mains is only that needed to supply losses. The test is, therefore, economical for long duration test like a “heat run”.