Swinburne Test of DC Machine

The Swinburne Test is a method for determining the performance characteristics of direct current (DC) devices like generators and motors. This test, named for its author, Thomas Swinburne, a renowned electrical engineer from the early twentieth century, gives useful information on the efficiency and overall health of DC equipment. If you are interested in electrical engineering, particularly DC machines, this test is very important. In this essay, we will go over the Swinburne Test, including its aim, methodology, and significance in the evaluation of direct current machines.

What is Swinburne’s Test?

Swinburne’s test (named after James Swinburne) is an indirect method for evaluating a DC shunt or DC compound motor. During this test, the motor is unloaded. As a result, this kind of testing is also known as No-load Testing. The Swinburne’s test is extremely useful for very huge machines that cannot be tested under actual load. As a result, this technique contributes to the understanding of the performance characteristics of big DC machines.

Swinburne’s Test Circuit Diagram

Swinburne’s test is used to calculate the motor’s losses and efficiency at any specified load. In this test, the DC machine functions as a motor with no load. The stimulation is delivered to the motor so that it can function at rated voltage and speed. The connection diagram for Swinburne’s test is illustrated in the image below.

This is an indirect approach for testing a DC machine. It’s named after Sir James Swinburne. Swinburne’s test is the most widely used and easy way of checking shunt and compound wound DC devices with constant flux. In this test, the machine’s efficiency at any load is predetermined. We may use the machine as a motor or generator. In this type of testing, no load losses are assessed independently, allowing us to calculate efficiency.

The circuit connection for Swinburne’s test is illustrated in the diagram below. The speed of the machine is regulated to the rated speed using the shunt regulator R, as illustrated in the figure.

Swinburne Test for DC Machine

The Swinburne’s test may be used to determine the losses in DC machines when there is no load. DC machines are just motors or generators. This test is only relevant to big shunt DC devices with constant flux. It is relatively simple to determine the machine’s efficiency in advance. This test is cost-effective since it needs little input power with no load.

Swinburne Test for DC Shunt Motor

Swinburne’s test on a DC shunt motor may be used to determine machine losses when there is no load power. The motors’ losses include armature copper losses, iron losses in the core, friction losses, and winding losses. These losses are computed independently, and efficiency may be predetermined. The shunt motor’s output is zero with no-load power input, hence this input no-load is utilized to provide the losses. Because the change in iron losses cannot be calculated from no-load to full-load, and the change in temperature increase cannot be detected at full load.

Calculation of Efficiency

Let I₀ be the no-load current (which may be measured by an ammeter A₁).

I_sh is the shunt field current (it may be measured with ammeter A₂).

The no-load armature current = ( I₀ – I_sh)

The supply voltage (V). As a result, the power input with no load equals V I₀ watts.

Swinburne’s test requires no load power input, merely to provide losses. The losses that occur in the machine mostly include:

• Iron loss in the core
• Friction and winding losses.
• Armature copper loss.

Swinburne’s test determines that the machine’s no load mechanical output is zero, hence the no load input power is simply utilized to provide losses.

The armature copper loss is = ( I₀ – Ish)² R_a

the armature resistance (Ra).

Now, to calculate the constant losses, we must remove the armature copper loss from the no-load power input.

Constant losses W_c = V I₀ – ( I₀ – I_sh )² R_a

After computing the no-load constant losses, we may compute the efficiency at any load.

Let I be the load current used to calculate the machine’s efficiency.

When the machine is running, the armature current (Ia) will equal (I – Ish). When the machine motoring

And I_a = ( I + I_sh ) when the machine is generating.

Efficiency of Motor

Efficiency of a DC Machine When running as a motor, 

load current = I_L in Ampere.

Load voltage = V in Volt.

Total input power = V I_L in Watts.

The total constant losses are the same as calculated above.

Total constant losses: P_C = V I_O – (I_O – I_sh)² R_a 

Armature copper loss = (I₀ – I_Sh)² R_a

Total losses: P_T = P_C + (I₀ – I_Sh)² R_a = V I₀ – (I0-I_Sh)² R_a + (I₀-I_Sh)² R_a

Output = Input-P_T = V I_L-P_T

Efficiency of a Motor

η_g = Output / Input x 100

η_g = ( V IL ) / ( V IL + PT ) x 100%

Efficiency of Generator 

Efficiency of DC machines. When running as a generator, the load current (Amp) is supplied at the load voltage (volts).

Generator output = V I_L – Watts.

Armature copper loss = I_a² R_a.

For generator: I_a = I_L + I_Sh.

Therefore, armature copper loss = (I_L + I_Sh)² R_a.

Constant loss: P_C = V I₀ – (I₀ – I_Sh)² R_a.

Therefore, total losses in the generator = P_T = P_C + (I_L + I_Sh)² R_a.

P_T = V I₀ – (I₀ – I_Sh)² Ra + (I_L + I_Sh)² R_a.

Input = output + all losses.

Input = V I_L + P_T, indicating generator efficiency.

Generator Efficiency

η_g = Output / Input x 100

η_g = ( V I_L ) / ( V I_L + P_T ) x 100%

Differences Between Swinburne’s Test and Hopkinson’s Test

Swinburne’s Test	Hopkinson’s Test
It is an indirect way for evaluating DC machines.	It is a regeneration test, back-to-back test of DC machinery.
It’s used to determine efficiency and no-load losses.	It is also used for determining efficiency and no-load losses.
It is appropriate for big shunt machines with no-load input power.	It is appropriate for big shunt machines with no-load input power.
Only one shunt machine is employed. During this test, the DC machine operates as a motor or generator just once.	Two shunt machines are used. One serves as a motor, while the other as a generator.
It is both easy and affordable.	It is both affordable and difficult to execute since two shunt machines are utilized.
It is quite challenging to discover commutation conditions and temperature increase at full load.	It is quite simple to determine the temperature increase and commutations at any load with rated voltage.

Advantages and Disadvantages of Swinburne Test

The Advantages and Disadvantages of Swinburne’s test for DC machines are stated below :

Advantages

• big-scale machinery cannot be tested with a big load. Because this test is performed in a no-load environment, it is appropriate for laboratory testing without real loading.
• It takes less time to complete this exam.
• Because we have not connected the whole load, the input power is simply needed for losses. As a result, this test requires very little electricity.
• Losses and efficiency of a machine are estimated under all load conditions.
• The energy loss during this test is quite minimal. As a result, this test does not create significant heat.
• This test evaluates DC shunt and complex wound machines.

Disadvantages

• Iron loss is ignored, yet there is a shift in iron loss from no load to full load owing to armature response.
• We cannot be certain that the commutation is adequate in loaded conditions because the test was performed under no load.
• We cannot measure the temperature increase while the machine is loaded. Power losses might vary according on the temperature.
• Swinburne’s test cannot be used to determine efficiency in DC series motors since it is a no-load test.

Applications of Swinburne’s Test

• This test is used to determine the efficiency and no-load losses of DC machines with constant flux.
• In DC devices, when used as motors
• In DC devices when operating as generators
• Used in big shunt DC motors.

Conclusion

In conclusion, the Swinburne Test for DC machines is a fundamental method for determining these machines’ efficiency and performance in actual operating conditions. This test, which was created by John Swinburne, involves simulating a variety of loads and measuring important parameters like voltage, current, speed, and torque. The machine’s capacity to convert electrical power into mechanical power is better understood thanks to the calculated efficiency. Specialists can utilize the information got from the Swinburne Test to settle on informed conclusions about upgrading the machine’s exhibition and limiting misfortunes.

FAQs on Swinburne Test of DC Machine

What is the purpose of the Swinburne Test?

The Swinburne Test is essential for surveying the proficiency and misfortunes of DC machines in reasonable situations. It gives important information to designers to settle on informed conclusions about execution advancement and enhancements.

Can any DC machine be tested using the Swinburne Test?

Yes, the Swinburne Test is a versatile method that can be used on generators and motors as well as other DC machines.

What essential measurements were taken during the examination?

Basic estimations incorporate voltage, current, speed, force, and power. These estimations are fundamental for working out effectiveness and figuring out the machine’s exhibition.

The Swinburne Test contributes to machine optimization in what way?

The Swinburne Test identifies losses within the machine by simulating realistic operating conditions. This enables engineers to optimize the machine’s design, adjust parameters, and improve overall performance.

Can a small prototype be used for the Swinburne Test?

Indeed, the Swinburne Test can be adjusted for various machine sizes, making it appropriate to both huge scope modern machines and more modest models utilized in innovative work.