Tan delta test on transformer pdf

It is a Oil and gas actuated Protection Relay for Mechanical…. You must be logged in to post a comment. Skip to content. Measure and record the ambient temperature and relative humidity for reference. Short the Terminals of the bushings of each winding together using bare braided copper jumper.

These jumpers shall not be allowed to sag. Connect the ground terminal of the test set to a low impedance earth ground to Earth mat of the substation. Subscribe to get more post like these!! Just enter your Email Adress and hit the Subscribe Button!!!!!! Previous Previous. Next Continue. Similar Posts. Log in to Reply. Leave a Reply Cancel reply You must be logged in to post a comment.

When a pure insulator has a connection between the earth and the line, then it performs like a capacitor. In an ideal kind of insulator, as the insulating substance functions as a dielectric, which is totally pure, then the passage of current through the material holds only capacitive material.

There will be no resistive element for the electric current that is flowing from the line to the earth via insulator as in the insulating component, there will be no presence of impurities. The tan delta test circuit diagram is shown as follows:. In a pure capacitive material, the capacitive current precedes the voltage level by 90 0.

As a general, the insulating material is totally pure, and even because of the aging properties of the components, the contaminations such as moisture and dirt might get added. These contaminations create a conductive path for the current. As a result, leakage current that flows from line to earth via the insulator holds resistive elements. Therefore, it is pointless to claim that, for a good quality of insulator, this resistive element of leakage current is correspondingly minimal.

In the other aspect, the behavior of an insulator might be known by the proportion of the resistive element to that of the capacitive element.

In a few cases, this is also expressed as a dissipation factor. With the below-depicted vector diagram, it can be known. Where the x-axis represents the level of system voltage which is the resistive element of leakage current I R. As this capacitive element of leakage current I C precedes by 90 0 , it is taken across the y-axis.

The below process explains the method of tan delta testing in a step-by-step manner. It has to be noted that the testing procedure to be carried out at very minimal frequency levels. It is more recommended to conduct testing at minimal frequency levels, because when the applied voltage level is more, then the capacitive reactance of the insulator device reaches very minimal, therefore the capacitive element of the current reaches more.

Whereas at increased frequency level the capacitive current, is more, and then the amplitude of the vector amount of both the capacitive and resistive elements of the current reaches very high. So, the necessary level of power for the tan delta test would become more that seems to be not acceptable.

Because of this, the power constraint for dissipation factor analysis, very minimal frequency test voltage is required. These exist mainly two approaches to analyze the situation of the insulation method at the time of tan delta testing. The first is, evaluating the past test results to know the worsening of insulation conditions because of the aging effect.

When the insulation results are accurate, then the loss factor values are nearly similar for the entire test voltage values. These outcomes might be matched with the outcomes of past tested insulators, to go with the appropriate decision either the equipment has to be substituted or not.