File Name: open and short circuit test on transformer .zip
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.
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.
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. This method of finding the parameters of a transformer is called as an indirect loading method. Open circuit test and short circuit test on the transformer are very economical and convenient because they are performed without actually loading of the transformer. In fact, the testing of very large a. The circuit diagram for open circuit test is shown in the figure. Usually, high voltage HV winding is kept open and the low voltage LV winding is connected to its normal supply.
It is possible to predict the performance of a transformer at various loadings by knowing all the equivalent circuit parameters. Without actually loading the transformer, these two assessed tests give the test results which are used to determine the equivalent circuit parameters. By these parameters, we can easily predetermine the efficiency and regulation of the transformer at any power factor condition as well as at any load condition.
A transformer is a static electrical machine that transfers electrical energy between 2 or more circuits through the principle of electromagnetic induction. As shown in Figure 1, the transformer consists of a core usually laminated steel , a primary winding and a secondary winding. A time varying current in the primary coil produces a time varying magnetic field. This time varying magnetic field induces a voltage in the secondary coil.
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.
Я зарабатываю гораздо больше, чем в состоянии потратить, - думала она, - поэтому будет вполне естественным, если я буду платить. Но если не считать его изрядно устаревших представлений о рыцарстве, Дэвид, по мнению Сьюзан, вполне соответствовал образцу идеального мужчины. Внимательный и заботливый, умный, с прекрасным чувством юмора и, самое главное, искренне интересующийся тем, что она делает. Чем бы они ни занимались - посещали Смитсоновский институт, совершали велосипедную прогулку или готовили спагетти у нее на кухне, - Дэвид всегда вникал во все детали. Сьюзан отвечала на те вопросы, на которые могла ответить, и постепенно у Дэвида сложилось общее представление об Агентстве национальной безопасности - за исключением, разумеется, секретных сторон деятельности этого учреждения.
Элементы! - повторил Беккер. - Периодическая таблица.
Мы будем ждать. Джабба открыл рот. - Но, директор, ведь это… - Риск, - прервал его Фонтейн. - Однако мы можем выиграть.
- Панк не понимал, к чему клонит Беккер.
Да, но я на всякий случай заглянул в Интернет, запустив поиск по этим словам. Я не надеялся что-либо найти, но наткнулся на учетную запись абонента. - Он выдержал паузу. - Я, конечно, предположил, что это не та Северная Дакота, которую мы ищем, но на всякий случай проверил эту запись. Представь себе мое изумление, когда я обнаружил множество сообщений Энсея Танкадо.
Уже два часа утра. - Pi'dame uno.
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