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.
What is meant by brake test?
A brake test, also known as a brake check, occurs when a driver deliberately brakes very hard in front of another driver who is tailgating, or immediately after overtaking as an aggressive action, causing the second driver to swerve or otherwise react quickly to avoid an accident.
What is the purpose of brake test?
The purpose of the braking test is to measure the vehicle braking from 60-0 mph (20-0 mph for NEVs).
What is load test on DC shunt motor?
The brake test is the one kind of load test on dc shunt motor. Generally, this test can be done for the low rated DC machines. The main reason for doing this test is to identify the efficiency and also by using this test, the output of mechanical power can be calculated & separate the same by using electrical input.
Why is the brake test not normally done on large capacity motor?
Because in the case of large motors. It is difficult to dissipate the large amount of heat generated at the brake. … For a constant applied voltage, the field current is constant for a D.C. Shunt motor.
Is it legal to brake check a tailgater?
When you’re being tailgated, it’s a natural impulse to want to get the other driver off your back. Unfortunately, some motorists attempt to do this by brake checking — a dangerous behavior that’s illegal and considered aggressive driving in many states.
What are the 3 types of DC motors?
Types of DC Motors. There are 3 main types of DC motor that are available:- Series, Shunt and Compound. These terms relate to the type of connection of the field windings with respect to the armature circuit.
Are Brake checks legal?
What is “Brake Checking”? Brake checking is the act of unexpectedly is slamming on your brakes because the person behind you is tailgating or following too closely. Brake checking is not legal, it can lead to serious injury including a wreck with fatalities.
How do you check brake performance?
The performance of a braking system shall be determined by measuring the stopping distance in relation to the initial speed of the vehicle and by measuring the mean fully developed deceleration during the test.
How do I stop brake checks?
Always swerve to the right (if you drive on the right). If you have dash cam of a driver changing lanes directly in front of you and slamming on brakes, then it would be their fault. If someone who has been in front of you for a bit brake checks you, it’s your fault. If you swerve and hit someone, it’s your fault.
What are the advantages of DC shunt motor?
Advantages of DC Shunt Motors
- direct current machines can use for heavy industrial applications where torque and speed wider range.
- Shunt wound motor able to runs at a predetermined speed.
- The power supply of DC motor is any way cheap.
Why DC shunt motor is constant speed?
Since torque is proportional to armature current, torque also increases. Finally, this increased torque allows the motor to increase its speed and compensate for the slowdown due to loading. Hence, a DC shunt motor is able to self-regulate its speed, and can be referred to as a constant speed motor.
What are the characteristics of DC shunt motor?
Characteristics of a DC Shunt Motor:
- Speed-Armature Current Characteristic: …
- Torque-Armature Current Characteristic: …
- Speed-Torque Characteristic: …
- Break in Field Circuit of a DC Motor:
Which is main disadvantage of Swinburne’s test?
Disadvantages of Swinburne’s Test
Iron loss is neglected though there is change in iron loss from no load to full load due to armature reaction. We cannot be sure about the satisfactory commutation on loaded condition because the test is done on no-load. We can’t measure the temperature rise when the machine is loaded.
Can we conduct field test on DC shunt motor?
INDIRECT METHOD OF TESTING:
If the losses are known, then efficiency can be determined. Swinburne’s test and Hopkinson’s test are commonly used on shunt motors. But, as series motor cannot be started on No-load,these tests cannot be conducted on DC series motor. (i) BRAKE TEST: is a direct method of testing.
How does performance test for DC generators are conducted?
Short Circuit Test
In this testing of DC machine the armature is short circuited with an ammeter to get the short circuit current. Short circuit test gives the short circuit characteristic curve which shows the variation of short circuit current as a function of excitation current.