The Swinburne test is only applicable for motors where flux is virtually constant, which includes DC shunt and compound motors. The test does not work for series motors because they cannot be run at light loads, and because speed and flux vary significantly in series motors.
Can a Swinburne’s test be applied to a dc series motor?
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. 2. … We also get shunt field losses and variable loss occurring in armature resistance.
Which test is not suitable for dc series motor?
Swinburn’s test and retardation tests are no-load tests. So, these methods of testing are not possible with series motors as series motors have a tendency of attaining dangerous high speed at no load. Hence these tests prefer constant flux machines i.e. shunt (or) compound machines.
Why Swinburne’s test is preferred instead of brake test in dc machines?
The main advantages of this test are: This test is very convenient and economical as it is required very less power from supply to perform the test. Since constant losses are known, efficiency of Swinburne’s test can be pre-determined at any load.
Why Swinburne test is conducted only on shunt machine?
Swinburne Test of DC Machine
Since DC machines are nothing but motors or generators. This test is applicable only for the large shunt DC machines which have constant flux. It is very easy to find the efficiency of the machine in advance. This test is economical because it requires a small input power with no-load.
Why Swinburne’s test is called No Load Test?
Due to armature reaction flux is distorted at full load and, as a result, the iron loss is increased. As the Swinburne’s test is performed at no load. Commutation on full load cannot be determined whether it is satisfactory or not and whether the temperature rise is within the specified limits or not.
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 field test on DC series motor?
Field test is the method to calculate the efficiency of DC Series Motor and Generator at any desired load. Nvis 7022 also includes experiments such as Open Circuit Characteristic, Internal and External Characteristic of DC Series Generator in an easiest manner.
What is DC series motor?
Series DC motors are a group of self-excited DC motors in which the field coil is connected in series to the armature winding and thus a higher current passes through it. A series DC motor mission is to turn the electrical energy into mechanical one based on electromagnetic law.
What is brake test on DC series motor?
In the case of a brake test on a dc generator, an electrical load is applied at the generator terminals. … By varying the weight of the wooden blocks on the motor, the load is adjusted till it carries full-load current. The load on the motor shaft is varied step by step up to its full-load current.
What is the difference between Swinburne’s and Hopkinson’s test?
In Hopkinson’s test we need a pair of both motor and a generator whereas in Swinburne’s we need only one. The temperature rise can be observed in Hopkinson’s test because this test is done under full load conditions but since Swinburne’s test is done in no-load conditions, we cannot observe the temperature rise.
What is the difference between a DC shunt and a series motor?
A series motor respond by decreasing its speed with small increase in current for a given load torque. A shunt motor holds its speed nearly constant with large increase in input current for same amount of load torque.
Why brake test is conducted on DC shunt motor?
In Direct Method, the DC machine is subjected to rated load and the entire output power is wasted. The ratio of output power to the input power gives the Efficiency of DC Machine. For a DC Generator the output power is wasted in resistor. Direct Method of testing when conducted on a motor is also known as Brake Test.
Why series motor is never started on no load?
A series motor should never be started at no load. With no mechanical load on the series motor, the current is low, the counter-EMF produced by the field winding is weak, and so the armature must turn faster to produce sufficient counter-EMF to balance the supply voltage. The motor can be damaged by overspeed.
Why is Swinburne test performed?
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 the purpose of Hopkinson’s test?
Definition: A full load test which is used to test the efficiency of a DC machine is known as Hopkinson’s test. An alternate name of this test is back to back, heat run, and regenerative test. This test uses two machines which are connected electrically and mechanically with each other.