What is Hopkinson test in DC machine?
Hopkinson’s test is a method of testing the efficiency of DC machines. The Hopkinson’s test is known as regenerative test or back-to-back test or heat-run test. This test requires two identical shunt machines which are mechanically coupled and also connected electrically in parallel.
How do you test a DC shunt motor?
first test the field winding with a megohmmeter to check, that the winding has no short to the housing. Then check the current consumption of the field winding. If you can, start with a low voltage and rise it until you reach the nominal voltage. Look for the maximum current at the specification plate.
What is Swinburne’s test on a DC machine?
Swinburne’s test is the simplest indirect method of testing dc machines. In this method, the dc machine(generator or motor) is run as a motor at no-load and losses of the machine are determined. Once the losses of the machine are known, its efficiency at any desired load can be determined in advance.
What is brake test on DC shunt motor?
Concept of Brake test: It is a direct method to determine the efficiency of DC motor. It consists of applying a brake to a water-cooled pulley mounted on the motor shaft as shown in fig. The brake band is fixed with the help of wooden blocks gripping the pulley.
Why Hopkinson test is called regenerative test?
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. The test is, therefore, economical for long duration test like a “heat run”.
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.
What are the testing methods of DC motor?
The main tests used for DC machines are:
- Open circuit test.
- Short circuit test.
- Load test.
- Determination of efficiency.
What is the main difference between brake test and Swinburne’s test?
Swinburne’s test is Indirect method of testing and brake tests are direct method of testing.
What is the advantage of Swinburne’s test on DC machine?
Advantages of Swinburne’s Test The power required for the testing of large machines is very small, therefore it is an economical and convenient method of testing DC machines. As the constant losses are known, thus the efficiency can be pre-determined at any load.
What is the purpose of brake test?
The purpose of this test is to measure the brake factors and thus determine the adhesion utilization of the front and rear axles over a range of braking rates between 0.15 and 0.8 .
What is the break test?
Break testing in manual muscle testing, is when resistance is applied to the body part at the end of the available range of motion. It’s called the break test because when a therapist provides resistance the objective for the patient is to not allow the therapist to “break” the muscle hold.
What are the advantages of Hopkinson test?
Advantages of Hopkinson’s Test Temperature rise and commutation can be observed and maintained in the limit because this test is done under full load condition. Change in iron loss due to flux distortion can be taken into account due to the advantage of its full load condition.
What will happen if field current of generator in Hopkinson test 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.
Can we do regenerative test on DC series?
Hopkinson’s test of dc machine is also known as a Regenerative Test. This test is also one of the efficient ways of determining the losses and efficiency of a dc machine. The test is performed by mechanical coupling of two identical dc machines. In which one machine works as a generator and the other as a motor.
Why is dc machine test done?
Testing of machines is used for finding Losses, Temperature rise and Efficiency. The efficiency of a d.c. machine depends on its losses. When losses are decrease, The efficiency is increase and it is vice-versa.
Can you test a DC motor with multimeter?
Attach the clip of the black lead wire to the DC motor and run the black motor wire to the battery. Attach the red and black lead wires to the volt meter on the red and black terminals respectively. Look at the display on the voltmeter and check for the ohm reading.
Can we conduct Swinburne’s test on DC series motor?
1. Swinburne’s test can be carried out on all DC motors. Explanation: Swinburne’s test is a no-load test; thus, it is performed only on shunt and compound motors. DC series motor is not advisable to start at no-load so, this test can’t be performed on series motor.
What is Hopkinson’s test on DC machines?
Regenerative or Hopkinson’s test on dc machines is useful to determine the efficiency which the power.This method of determining the efficiency of a d.c. machine saves power and gives more accurate results. In order to carry out this test, we require two identical d.c. machines and a source of electrical power.
What are the essential connections for Hopkinson’s test?
The below figure shows the essential connections for Hopkinson’s test.Two identical d.c. shunt machines are mechanically coupled and are connected in parallel across the d.c. supply.By adjusting the field strengths of the two machines, the machine M is made to run as a motor and machine G as a generator.
How to test the efficiency of a DC machine?
Hopkinson Test. 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.