What is brake test on DC compound motor?
It is a direct method and consists of applying a brake to a water cooled pulley mounted on the motor shaft. The brake band is fixed with the help of wooden blocks gripping the pulley. One end of the band is fixed to earth via a spring balance S1 and the other is connected to a suspended weight W1.
Why is brake test used to determine the efficiency of a DC 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.
How do you conduct brake test on DC shunt motor?
PROCEDURE: 1) Make the connections as per the circuit 2) Give Supply to the motor, by closing DPST switch 3) Start the motor with the help of 3- Point starter. 4) Adjust the speed of the motor to its rated value by varying either field or armature Rheostat as per the requirement. 5) Note down the no load readings.
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 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 .
Why do we use break tests?
The test requires no other machines thereby reducing the cost and energy. This method is very simple. Very much convenient for small dc motors. The efficiency can be determined under any actual load conditions from no-load to full-load.
What is the purpose of conducting break test?
1. 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 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 direct method of testing in dc machine?
In direct method of testing the generator or motor is put on full load and whole of the power developed by it is wasted,. Brake test is a typical example of direct test. The direct tests can be used only on small machines.
How is brake test performed?
The vehicle is braked after wetting of the brakes, from the initial speed with control force as has been mentioned in the standard. The test consists of 15 stoppages, with an interval of 120 s between two stoppages. During each stoppage, the mean deceleration value is calculated.
How do you measure brake performance?
Ebrake = VW / BE * 100
- Where Ebrake is the Brake Efficiency (%)
- VW is the total vehicle weight (lbf)
- BE is the brake effort (lbf)
How is a break test used to determine strength?
One of the most common of all testing requirements is the determination of break strength. Break strength is generally the tensile or compressive load required to fracture or to cause the sample to fail. To determine the failure point or break strength, you will need to define what a break is (break detector).
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.
Why Swinburne’s test is preferred instead of brake test in DC machines?
The main advantages of Swinburne’s test are as follows: The power required to test a large machine is small. Thus, this method is an economical and convenient method of testing of DC machines. As the constant loss is known the efficiency can be predetermined at any load.
What is the purpose of Swinburne’s 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 are the direct and indirect test in a dc machine?
Testing of machines is used for finding losses, efficiency and temperature rise. Direct method is used, for small machines. Indirect method is used for large shunt machines.
What is the major difference between the direct and indirect testing?
Direct – The assessment is based on an analysis of student behaviors or products in which they demonstrate how well they have mastered learning outcomes. Indirect – The assessment is based on an analysis of reported perceptions about student mastery of learning outcomes.
What does brake performance mean?
The braking performance of trains is the general performance of the braking system of locomotives (or motor cars) and cars (or trailer), and is a guarantee for the safety and improvement of braking deceleration.
How does a brake test work?
The brake tester consists of weighing cells on each side of the unit with a safety roller that detects whether a vehicle is present in the tester – this will also monitor any tyre slippage. The vehicle is driven onto the brake tester with its wheels centrally located between the two larger main rollers.
What is a brake efficiency test?
The most common method of testing brakes is to take the vehicle on the road, bring it up to speed, and then slam on the brakes! We can then measure stopping distance or use a decelerometer to measure the stopping forces created in %G.
How do you do a 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. 2.
What is the formula of breaking strength?
Difference Between Tensile Stress And Tensile Strength
| Tensile stress | Tensile strength |
|---|---|
| The formula is: σ = F/A Where, σ is the tensile stress F is the force acting A is the area | The formula is: s = P/a Where, s is the tensile strength P is the force required to break a is the cross-sectional area |
Why do we do brake test?
It is often used as a warning that you are following too close, or if the driver is undergoing a road rage incident because (rightly or wrongly) he or she is annoyed at your driving. Brake testing is not where the driver in front of you brakes heavily genuinely. Brake testing is extremely dangerous.
How do you do a brake test?
Step on the brake and hold the pedal down for one minute. There should be no more than 3 psi of air loss. Listen for any possible leaks. TEST 3: Service brake warning system test.