testing of DC machine

The testing of dc machine:

The testing of dc machine is required for legitimate creation and smooth inconvenience free task. The tests which are fundamentally required for these reasons for existing are –

1) Open circuit test

2) Short circuit test

3) Load test

4) Efficiency test

Open Circuit Test:

The open circuit test is expected to decide the open circuit characteristic or magnetic characteristic for a dc machine. The open circuit test gives the mmf and henceforth the excitation current or field current expected to produce the required voltage on no heap at a settled speed. The open circuit characteristic curve demonstrates the variety of instigated emf as an element of field current at consistent speed and zero load current.

This curve is for all intents and purposes controlled by running the machine as a separately excited generator on-stack. This curve is additionally called no load saturation curve as it gives the saturation characteristic for the generator.

Short circuit Test

The short circuit test is expected to decide the voltage drop over the armature at any load current. In this testing of DC machine, the armature is short-circuited with an ammeter to get the short circuit current. Short circuit test gives the short circuit characteristic curve which demonstrates the variety of short circuit present as a component of excitation current.

Load Test

The load testing of DC machine is expected to decide the rating of a machine. When we run a machine, at that point some energy is lost in the machine, which changes over into the heat and cause temperature rise. In the event that a machine creates excessively heat then it can influence the protection of the machine and at last it can cause the breakdown of the machine. In this manner, the load must be set to an esteem that it can work inside as far as possible. The most extreme estimation of the load that can be conveyed by the machine with no mischief is known as the consistent rating of that machine.

Determination of Efficiency

The Efficiency of DC machine like some other machine is dictated by the ratio of output power to that of the input power.

There are three techniques for deciding the Efficiency of a machine.

1) direct technique

2) indirect technique

3) Regenerative technique

The first condition is giving a thought regarding the immediate estimation of the productivity. In this strategy the machine is completely stacked and the yield is straightforwardly estimated. This strategy for estimation is connected for the little machines.

The second and third conditions are giving a thought regarding the aberrant estimation of the effectiveness.

Aberrant strategy is useful of deciding the proficiency of shunt wound generator and compound injury generators. In this strategy it is required to decide to decide the misfortunes as it were. Along these lines, control supply is required to supply the misfortunes just without stacking the machine. For the regenerative technique for deciding effectiveness, it is required to have two indistinguishable machines. One machine is utilized as engine and drives the other and the other is utilized as generator and input the power into the supply. Two machines are mechanically coupled. Consequently, the misfortunes can be resolved on the grounds that the inside influence attracted is just to supply misfortunes of the two machines. But these testicles, the protection test and the test for making the recompense palatable is done while developing the machine.