What is a regenerative test?
Hopkinson’s test of dc machine 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 Hopkinson test conducted?
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 is Swinburne test?
The Swinburne test is an indirect method for determining the efficiency of DC motors. It works by finding the no-load losses experimentally and then estimating additional losses from the rated motor data. From this information, the efficiency can be determined at any applied load.
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.
Can we conduct regenerative test on dc series motor?
In the case of DC Series Motor an increase in speed is followed by a decrease in the armature current and field flux. The back EMF Eb cannot be greater than the supply voltage. Regeneration is possible in DC Series Motor since the field current cannot be made greater than the armature current.
What are the different tests conducted on dc machines?
The main tests used for DC machines are:
- Open circuit test.
- Short circuit test.
- Load test.
- Determination of efficiency.
Which test on DC machine is known as running down test?
Retardation test is also called as running down test. This is the very efficient way to find out stray losses in dc shunt motors. In this test, we get total stray losses nothing but the combination of mechanical (friction & windage) and iron losses of the machine.
What is Ward Leonard method?
Definition of Ward Leonard system : a regenerative electrical system by which variations in motor speeds for all loads carried by a motor are obtained without rheostatic losses in the main circuit.
What is load test on DC shunt motor?
The brake test is the one kind of load test on the dc shunt motor. Generally, this test can be done for the low-rated DC machines.
What is brake test on DC series motor?
In the brake test, the dc machine is tested by actual loading with the help of breaks. Since the load is applied directly to the machine shaft, it is a direct method of testing a dc machine.
Can Hopkinson’s test be performed on any two dc machines?
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.
Why is regenerative braking not possible in DC series motor?
Why? In case of DC Series motor, as the speed of Motor increases, the armature current and hence the field flux will decrease and therefore Back emf E can never be greater than the supply voltage V. Therefore, Regenerative Braking is not possible in DC 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.
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.
How can we measure the total loss of the machines?
By adjusting the field strengths of the machines, any load can be put on the machines. Therefore, we can measure the total loss of the machines at any load.
Why can’t we load the two machines equally?
Both machines cannot be loaded equally all the time. It is not possible to get separate iron losses for the two machines though they are different because of their excitations. It is difficult to operate the machines at rated speed because field currents vary widely. Get electrical articles delivered to your inbox every week.