What is excitation current test in transformer?

Excitation current is the current flowing into the high voltage winding with the low voltage side open. This current should be proportional to the No-load acceptance test but with the difference resultant from the use of test voltages different from nominal values.

What is TTR test?

Transformer Turns Ratio (TTR) testing is one of the most common ways of assessing the condition of a transformer’s windings and core. Throughout the life of a transformer, TTR results are compared against the nameplate ratings to reveal insulation deterioration, shorted turns, core heating or other abnormalities.

What are the different tests conducted in a single phase two winding transformers?

Four Methods for Testing Transformers

• Turns Ratio Testing. Turns ratio transformer testing is commonly used to ensure that the winding ratio between the primary and secondary coils are aligned to recommended specifications.
• Insulation Resistance Testing.
• Power Factor Testing.
• Resistance Testing.

How many types of transformer tests are there?

Transformer manufacturers perform two main types of transformer testing – type test of transformer and routine test of transformer. Some transformer tests are also carried out at the consumer site before commissioning and also periodically in regular and emergency basis throughout its service life.

What is core loss current?

Definition of ‘core loss’ Core loss is the loss that occurs in a magnetic core due to alternating magnetization, which is the sum of the hysteresis loss and the eddy current loss. The term core loss relates to the total energy lost through the generation of heat.

What is CT excitation current?

A ct excitation curve provides a measure of the steady-state performance. Excitation curves have a knee-point voltage defined by the 45° line drawn tangent to the curve. However, it is important to note that the knee-point is the point of maximum permeability and not the point of saturation.

What is a polarity test?

What is Polarity Testing? A test that creates a circuit using the phase conductor and the single pole device in question, breaking the circuit when operating the device, means that the reading on the instrument will change, and thus confirming that that device must be connected in the phase conductor.

How many ohms should a transformer read?

Look for a reading of somewhere between one and about 10 ohms. If any winding reads higher than 10 ohms you have probably found a bad transformer. Unless you didn’t get a good connection to the coil leads with your test leads. Always check at least 3 times before you draw a conclusion.

What is the two types of transformer?

Transformers generally have one of two types of cores: Core Type and Shell Type. These two types are distinguished from each other by the manner in which the primary and secondary coils are place around the steel core.

What is no load test?

No Load Test is an indirect method used for determining the efficiency and also to determine the circuit parameters of the equivalent circuit of the three-phase induction motors. As the motor is running at no load, the total input power is equal to the constant iron loss, friction, and windage losses of the motor.

How is leakage reactance measured with single phase excitation?

Abstract: Low voltage and single-phase excitation are often used to measure leakage reactance or short-circuit impedance of transformers. Winding distortion may be detected by comparing field results with factory nameplate values measured at 25-100% of the rated current using three-phase excitation.

How can winding distortion be detected with single phase excitation?

Winding distortion may be detected by comparing field results with factory nameplate values measured at 25-100% of the rated current using three-phase excitation. The results of single- and three-phase excitation will not always correlate.

When does the excitation current flow in a transformer?

When normal voltage is applied to the terminals of a transformer with the secondary circuit open, a small current will flow in the primary. This current is called as transformer excitation current and flows all the time during the operation of the transformer.

Can a single phase excitation be influenced by magnetizing reactance?

The results of single- and three-phase excitation will not always correlate. If the voltage applied in the field is not properly selected then the data may be influenced by the magnetizing reactance.