# Testing of DC Machine

The testing of the DC machine is required for legitimate creation and smooth inconvenience-free tasks. The tests which are fundamentally necessary for these reasons for existing are –

1. Open circuit test
2. Short circuit test
4. Efficiency test

## Open Circuit Test

The open-circuit test is expected to decide a DC machine’s open-circuit characteristic or magnetic characteristic. The open-circuit test gives the MMF and, subsequently, 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 a consistent speed and zero load current.

This curve is controlled by running the machine as a separately excited generator on-stack. This curve is additionally called a 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 the DC machine, the armature is short-circuited with an ammeter to get the short circuit current.

The short circuit test gives the short circuit characteristic curve, which demonstrates the variety of short circuits present as a component of excitation current.

The load testing of the 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 causes temperature rise.

If a machine creates excessive heat, 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 esteem that it can work inside as far as possible.

The most extreme estimation of the load conveyed by the machine with no mischief is known as the consistent rating of that machine.

## Determination of Efficiency

The Efficiency of a 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.

• Direct technique
• Indirect technique
• Regenerative technique

The first condition is giving a thought regarding the immediate estimation of productivity. The machine is wholly stacked in this strategy, and the yield is straightforwardly estimated. This strategy for assessment is connected to the little machines.

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

An aberrant strategy helps decide the proficiency of shunt-wound generators and compound injury generators. In this strategy, it is required to determine the misfortunes as they were. Along these lines, the control supply is necessary to supply the troubles without stacking the machine.

For the regenerative technique for deciding effectiveness, it is required to have two indistinguishable machines. One machine is utilized as an engine and drives the other, and the other is utilized as a 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 to supply troubles of the two machines. But these testicles, the protection test, and the test for making the compensation palatable are done while developing the machine.

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