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# Open Circuit And Short Circuit Test On Transformer Pdf En

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## Open-circuit test

Apparatus required Theory details Open and Short Circuit Test on Transformer Open Circuit Test on Transformer Short Circuit Test on Transformer Observation table Calculation for Open Circuit Test Observations Table for short circuit test Calculation for Short Circuit Test Principle of DC Motor Speed Control of Dc Motor Field control method Circuit diagram Observations Table Aim:- To conduct parameters and losses in a single phase transformer by open circuit and short circuit test on single phase transformer.

Objective:- To determine the approximate equivalent circuit of single phase transformer. This will enable me to calculate all the different parameters in the open circuit and short circuit tests. Enabling me to predict results for an actual circuit and also compare values between actual and equivalent circuit to see how accurate the estimation or prediction is equipment.

Theory details:- A transformer can be defined as a static device which helps in the transformation of electric power in one circuit to electric power of the same frequency in another circuit.

The voltage can be raised or lowered in a circuit, but with a proportional increase or decrease in the current ratings. According to this principle an E. F is induced in a coil if it links a changing flux. The alternating flux induces voltage E1 in the primary P and E 2 in the secondary side.

It means there may be in addition to the secondary. The emf induced in the secondary winding is usually referred to as the emf due to transformer action. That is the flux is in the time phase with the current I e and various sinusoidal. Open and Short Circuit Test on Transformer 5. Open Circuit Test on Transformer The connection diagram for open circuit test on transformer is shown in the figure.

A voltmeter, wattmeter, and an ammeter are connected in low voltage LV side of the transformer as shown. The voltage at rated frequency is applied to that low voltage LV side with the help of a variance of variable ratio auto transformer. The high voltage HV side of the transformer is kept open. Now with the help of variance, applied voltage gets slowly increased until the voltmeter gives reading equal to the rated voltage of the low voltage LV side.

After reaching at rated LV side voltage, all three instruments reading Voltmeter, Ammeter and Wattmeter readings are recorded. Figure:- 4 open circuit on transformer Since, the secondary terminals are open no load is connected across the secondary , current drawn from the source is called as no load current.

On no-load, the approximate equivalent circuit shown in Fig. Under no-load condition the power input to the transformer is equal to the sum of losses in the primary winding resistance R1 and core loss. Since, no load current is very small, the loss in winding resistance is neglected. Hence, on no load the power drawn from the source is dissipated as heat in the core. Short Circuit Test on Transformer The connection diagram for short circuit test on transformer is shown in the figure.

A voltmeter, wattmeter, and an ammeter are connected in high voltage HV side of the transformer as shown. The voltage at rated frequency is applied to that HV side with the help of a variance of variable ratio auto transformer. The LV side of the transformer is short circuited.

Now with the help of variance applied voltage is slowly increased until the ammeter gives reading equal to the rated current of the HV side. After reaching at rated current of HV side, all three instruments reading Voltmeter, Ammeter and Watt- meter readings are recorded.

The ammeter reading gives the primary equivalent of full load current IL. As the voltage applied for full load current in short circuit test on transformer is quite small compared to the rated primary voltage of the transformer, the core losses in transformer can be taken as negligible here. The input power during test is indicated by watt-meter reading. As the transformer is short circuited, there is no output; hence the input power here consists of copper losses in transformer.

Since, the applied voltage Vsc is short circuit voltage in the transformer and hence it is quite small compared to rated voltage, so core loss due to the small applied voltage can be neglected. Hence the wattmeter reading can be taken as equal to copper losses in transformer. Let us consider wattmeter reading is Psc. These values could easily be referred to LV side by dividing these values with square of transformation ratio.

Observation table:- For open circuit test:- S. C IM Observations Table for short circuit test:- S. Discussion:- Transformers are the most universally applied pieces of electrical equipment. As such, they range in size from miniature units weighing ounces to huge units weighing tons.

All transformers, however, exhibit the same basic properties. When mutual induction is permitted between two coils or windings, a change in current flowing through one coil induces a voltage upon the other coil.

All transformers have a primary winding and one or more secondary windings. The electromagnetic coupling between the primary and secondary windings allows electrical energy to be transferred from the primary winding to the secondary winding.

Electrical current entering the primary winding appears as an electromotive force emf at the secondary. Connecting the secondary winding to a load allows the energy to be transferred to the load.

Since there is no electrical connection between primary and secondary windings only a magnetic connection , the source and load can be electrically isolated from each other by means of a transformer. When the voltage applied to the primary winding is raised above rated value, the iron core begins to saturate, which leads to a rapid increase in the magnitude of the magnetizing current. Saturation of the core also distorts the sinusoidal voltage and current waveforms. The resulting harmonics can lead to mechanical resonances which, in large transformers, can be damaging.

Transformers are also very susceptible to damage from short circuit currents. Aim:- To obtain speed control of DC shunt motor by 1. Varying armature voltage with field current constant. Varying field current with armature voltage constant 2. Objective:- The purpose of this experiment is to become familiar with operating principles, equivalent circuit models, and basic characteristics of a dc machine.

Dc machines are most commonly used in control and servomechanism, as well as industrial, applications. The applications range from small permanent-magnet dc motors at a fraction of a Watt in consumer electronics, to large industrial shunt dc machines having a separate field winding.

The machine used in this experiment is a representative of an industrial dc motor or generator with a rated power of tens of kilowatts. The greatest advantage of DC motors may be speed control. Apparatus required:- S. Theory details:- DC motor is used to drive a mechanical load. In this lab, a separately excited DC motor provides the load.

The load on the motor is adjusted by varying the generator field current. By increasing the field current of the DC motor, the load on the DC motor increases and thus the armature current increases. In general, DC motors are characterized by their torque-speed curves.

Since the measuring equipment for shaft torque is not available in the lab it is necessary to use alternative means of characterizing the DC motor. Principle of DC Motor This DC motor works on the principal, when a current carrying conductor is placed in a magnetic field, it experiences a torque and has a tendency to move.

This is known as motoring action. If the direction of current in the wire is reversed, the direction of rotation also reverses. When magnetic field and electric field interact they produce a mechanical force, and based on that the working principle of dc motor established.

One of the important features of dc motor is that its speed can be controlled with relative ease. Therefore speed control of dc motor is classified as; 3. Field is directly connected across the supply so flux is not changed due to variation of series resistance. ## open circuit and short circuit test on single phase transformer

If it is used for converting power from a high voltage to a low voltage, it is called a step-down transformer. The conversion efficiency of a power transformer is extremely high and almost all of the input power is supplied as output power at the secondary winding. The transformer may be represented by the equivalent circuit shown in figure 3. The parameters may be referred to either the primary or the secondary side. The series resistances R 1 and R 2 represent the copper loss in the resistance of the two windings.

To determine the circuit constant, efficiency and regulation of a transformer, without actually loading the transformer, we perform Open-Circuit and Short-Circuit tests. These tests give more accurate result than compared with the fully loaded transformer. And the power consumption in these tests is minimal as compared with the transformer's output on full load. A voltmeter V, an ammeter A, and a wattmeter W are connected in the low voltage lv side of transformer. The voltmeter v gives the rated voltage V 1 of the primary. A very small current I 0 , called the no-load current, flows in the primary side because the secondary side is open circuited.

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We conduct open circuit and short circuit test on single phase transformer to determine the efficiency and regulation of a transformer on any load condition and at any power factor.

#### Open circuit or No load test on Transformer

One winding of the transformer whichever is convenient but usually high voltage winding is left open and other is connected to its supply of normal voltage and frequency. A wattmeter W, voltmeter V and an ammeter A are connected in low voltage winding in the present case. With normal voltage applied to the low voltage winding, normal flux will be set up in the iron core, hence normal iron losses will occur which is recorded by wattmeter. As the no- load current in low voltage winding is small, cu loss is negligibly small in low voltage winding and nil in high voltage side. Hence, the wattmeter reading represents practically the core loss under no-load condition. In this test, the terminals of low voltage winding are short circuited and variable voltage is applied to the high voltage side through an auto-transformer.

The open-circuit test , or no-load test , is one of the methods used in electrical engineering to determine the no-load impedance in the excitation branch of a transformer. The no load is represented by the open circuit, which is represented on the right side of the figure as the "hole" or incomplete part of the circuit. The secondary of the transformer is left open-circuited.

The open circuit and short circuit test are performed for determining the parameter of the transformer like their efficiency, voltage regulation, circuit constant etc. These tests are performed without the actual loading and because of this reason the very less power is required for the test. The open circuit and the short circuit test gives a very accurate result as compared to the full load test. The purpose of the open-circuit test is to determine the no-load current and losses of the transformer because of which their no-load parameters are determined.

Каждый компьютер в мире, от обычных ПК, продающихся в магазинах торговой сети Радиошэк, и до систем спутникового управления и контроля НАСА, имеет встроенное страховочное приспособление как раз на случай таких ситуаций, называемое отключение из розетки. Полностью отключив электроснабжение, они могли бы остановить работу ТРАНСТЕКСТА, а вирус удалить позже, просто заново отформатировав жесткие диски компьютера. В процессе форматирования стирается память машины - информация, программное обеспечение, вирусы, одним словом - все, и в большинстве случаев переформатирование означает потерю тысяч файлов, многих лет труда. Но ТРАНСТЕКСТ не был обычным компьютером - его можно было отформатировать практически без потерь. Машины параллельной обработки сконструированы для того, чтобы думать, а не запоминать. То есть… как ты их вскрываешь.

Сьюзан старалась держаться поближе к шефу на небольшой платформе с металлическими поручнями. По мере того как они удалялись от двери, свет становился все более тусклым, и вскоре они оказались в полной темноте. Единственным освещением в шифровалке был разве что свет звезд над их головами, едва уловимое свечение проникало также сквозь разбитую стеклянную стену Третьего узла.

Это невозможно! - воскликнула она.  - Вы проверили сигналы ошибки. Быть может, в ТРАНСТЕКСТЕ какой-нибудь сбой и… - Все в полном порядке. - Но это значит, что пароль неимоверной длины. 