Which test gives us stray losses?

Abstract: A loading-back test has been used for the determination of the stray load losses in polyphase induction machines

induction machines

An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor can therefore be made without electrical connections to the rotor.

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Induction motor - Wikipedia

. This test, which was found to have a high degree of accuracy, enables the various losses to be separated. The application of the test is simple and convenient.

How are stray losses measured?

Stray load loss is obtained by subtracting recognized losses from total losses, and divid- ing by two.

What are the stray losses?

The stray (or additional) losses are the component of the total load loss and they are produced by electromagnetic flux in the windings, tank, core, core clamping plates, magnetic shields, etc. [I]. They are determined by subtracting the ohmic I2R component from the measured load loss.

What is stray losses in machine?

The stray load loss can be regarded as the difference of the total iron losses and harmonic rotor cage losses between the no load and load conditions.

What is stray losses in synchronous motor?

The stray losses in the rotor, generally grouped under the heading of rotor surface losses, are shown to be due to several effects, notably those due to the concentration of ampere-conductors in one slot and to the irregularities present in the stator m.m.f. wave.

Stray Load Losses | Losses | Detailed Lecture

What are stray losses in DC motor?

Stray Losses :

The loss due to sparking between the brushes and commutator segments, loss due to the armature reaction effect that distorts the flux distribution, and many more are considered as stray losses. Since they are difficult to measure, stray losses are considered as 1% of the total output power.

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 is Hopkinson test?

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.

Why retardation test is conducted?

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.

How do you test a transformer loss?

To calculate the loss of a transformer you need to know the actual voltage and current in both the primary and secondary. Multiply the voltage in volts by the current in amps of the primary of the transformer. Record the figure. Multiply the voltage in volts by the current in amps of the secondary of the transformer.

What is stray losses in transformer?

The stray losses / circulating current losses are the source of heat generation in the transformer and ultimately paper insulation aged or loses its insulation property or strength & failed during course of its service rendering the short of life expectancy.

How do you calculate iron losses in a transformer?

To calculate total iron losses, we need to add up all element losses. Where W h i is hysteresis loss of element i; W e i is eddy current loss of element i; W a i is anomalous current loss of element i; and ne is number of elements.

What is a summation test?

In the summation test, a putative conditioned inhibitor is presented in compound with a separately trained excitatory conditioned stimulus (CS) – that is, one that evokes a conditioned response.

What is a retardation test?

Definition. The retardation of acquisition test is one of the two widely accepted tests for whether a stimulus functions as a conditioned inhibitor, the other being the summation test. In the retardation test, a stimulus is first trained as a putative conditioned inhibitor.

What is acquisition test?

Definition. The retardation of acquisition test is one of two widely accepted tests for whether a stimulus functions as a conditioned inhibitor (see summation test for the other). In the retardation test, a stimulus is first trained as a putative conditioned inhibitor.

Why Hopkinsons test is called regenerative test?

One of these two machines is operated as a generator to supply the mechanical power to the motor and the other is operated as a motor to drive the generator. For this process of back to back driving the motor and the generator, Hopkinson's test is also called back-to-back test or regenerative test.

What is the difference between Swinburne's and Hopkinson's tests?

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 Sumpner test in transformer?

A full-load test on the large transformer is to be conducted to determine the maximum temperature rise of the transformer which is called as back-to-back test. The back-to-back test is also known as Sumpner's test or regenerative test.

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.

Why Swinburne's test is economical?

Swinburne's test is an indirect method of testing of DC machines. In this method the losses are measured separately and the efficiency at any desired load is predetermined. The power required to test a large machine is small. Thus, this method is an economical and convenient method of testing of DC machines.

Which losses can be identified from Swinburne's test?

Which losses can be identified from Swinburne's test? Explanation: We get total rotational losses occurring in a machine, which are equal to no-load core losses (iron + copper) and windage and friction losses. We also get shunt field losses and variable loss occurring in armature resistance.

What are the assumption made in Swinburne test?

In Swinburne's test no load power input is only required to supply the losses. The losses occur in the machine mainly are: Iron losses in the core. Friction and windings losses.

What is stray loss and constant loss?

Notice that, as Stray Load loss depends upon the load current therefore it is categorized under variable loss while Mechanical Loss (independent of load current) comes under constant loss. No load Iron Loss is constant and therefore it is under Constant Loss.

What is the cause of the stray load losses in the synchronous machine?

What is the cause of the stray load losses in the synchronous machine? Explanation: The stray load loss occurs due to stray fields. They are formed when the machine is being loaded.

What is a compound stimulus test?

Term. compound-stimulus test. Definition. a test procedure that identifies a stimulus as a conditioned inhibitor if that stimulus reduces the responding elicited by a conditioned excitatory stimulus; also called a summation test.