What are the tests done for transformer oil?
The “screen test” is a collection of physical, electrical and chemical tests for the transformer oil. These tests include dielectric breakdown, power factor, interfacial tension, acidity, and color. A larger quantity of oil is needed for these tests.
How is the power factor of a transformer calculated?
It is found by multiplying (kVA = V x A). The result is expressed as kVA units. PF expresses the ratio of true power used in a circuit to the apparent power delivered to the circuit.
Do transformers have power factor?
The power factor measured at the primary of the transformer is the result of applying the source voltage to the combined impedance of the transformer equivalent circuit and the load. The power factor at the secondary of the transformer is determined only by the load circuit.
What should be the BDV value of transformer oil?
That means at which voltage dielectric strength of transformer oil between the electrodes has been broken down. A typical value of BDV Test result for 220 / 6.6 kV Transformer oil is 65 kV and moisture content should be less than 10 ppm.
What is ppm test of transformer oil?
PPM stands for Parts Per Million. It is used to measure the weight of moisture divided by the value of oil. The moisture content in oil lowers the insulating system dielectric strength that permits flashover to harm a transformer. For example, for mineral oil, a generally accepted maximum moisture content is 35 ppm.
What is Liquid Power Factor?
Liquid Power Factor (PF) Dissipation Factor, or Liquid Power Factor, is a measure of the dielectric losses in an insulating liquid when used in an alternating current electric field. Liquid power factor is an electrical property of the oil, and relates both to the function of the oil and to its purity.
What is a transformer power factor test?
The power factor test is a maintenance test used to determine the insulation system dielectric power loss by measuring the power angle between an applied AC voltage and the resultant current. Power factor is defined as the ratio of the power dissipated divided by the input volt-ampere multiplied by 100%.
What is a transformer power factor?
Power factor (PF) is the ratio of true power used in an AC circuit to apparent power delivered to the circuit. Power factor is expressed as a percentage. True power equals apparent power when the power factor is 100%.
How does power factor affect transformers?
As the load on a transformer increases, the reactance decreases, and the power factor increases. At full load, the power factor approaches 1. Loads with a low power factor draw considerably more current than loads with a power factor near unity.
What is PPM test in transformer?
What is acidity test of transformer oil?
The acidity of insulating oil is generally measured by the required quantity in milligram of KOH to entirely neutralize the acidity of a specific quantity in gram of the oil. Acidity of an insulating oil is 0.3 mg KOH / g means 0.3 milligram of KOH is required to neutralize 1 gram of that insulating oil.
What is BDV test in transformer?
BDV test means the Breakdown Voltage Test. This test is performed for verifying the dielectric strength of the oil of the transformer. Dielectric Strength is the maximum capacity to resist the voltage of insulating oil. This test demonstrates the dielectric Strength of Transformer Oil.
Why do you need to test transformer oil?
Regular sampling and testing of insulation oil taken from transformers is a valuable technique in a preventative maintenance pr ogram. If a proactive approach is adopted based on the condition of the transformer oil, the life of the transformer can be extended.
What is the IFT test for a transformer?
The IFT test is a powerful tool for determining how an insulating oil has performed and how much life is left in the oil before maintenance is required to prevent sludge. The IFT provided an excellent back up test for the NN.
What are the objectives of power transformer testing?
Power transformer testing Objective of testing •Compliance to applicable standards •Compliance to customer specification •Verify guaranteed parameters •Assess quality and reliability •Verify design •Obtain additional performance and reference data 3 4Power transformer testing Classification of tests •Routine test •Design test
What should the power factor of a transformer be?
Modern oil-filled power transformers should have power factors of 0.5% or less, corrected to 20°C (68°F), for individual windings to ground (CH and CL) and interwinding insulations (CHL). The National Grid transformer specification states that the power factor of the insulation system shall not exceed 0.5% at 20°C.