Insulation Power Factor
Better known as the “DOBLE Test”, IPF or insulation power factor test is the most comprehensive measurement of insulating properties of a power transformer. Elements such as deterioration, contamination, moisture, and heat can breakdown dielectric strength. Insulation Power Factor Testing measures the dielectric losses due to leakage current thru the insulation.
Exciting Current Test
Typically part of preventive maintenance test procedures, the exciting current test is also performed during commissioning, acceptance, and after fault/trip. The Exciting Current Test provides information and measurement on abnormal core grounds, winding faults (shorts and open circuits), manufacturing defects, and load tap changer problems.
Also know as the Short Circuit Impedance Test, is a procedure that can be performed on a per-phase basis. This test can confirm Nameplate Impedance data, and detect winding deformation,
Transformer Turns Ratio
This test can detect shorted turns in the windings or a defective tap changer. The Turns Ratio Test (TTR) will detect and confirm a difference in voltages between phases. This means, that your transformer is not operating up to the manufacturer’s specifications and is not producing proper output voltages. This is also an early indication of transformer failure. It can also be used for transformer acceptance testing when a new transformer is installed. This will also be a base line for future diagnostics.
Winding Resistance Test determines the I2R losses in the transformer, and as a benchmark for assessing possible damages in the field. As a routine test procedure, this procedure is used to determine abnormalities due to loose connections, broken strands of conductors, high contact resistance in tap changers, high voltage leads, and bushings.
The insulation resistance test is a direct current evaluation test of the insulation and gives a reliable indication of the presence of moisture, contamination, or breakdown in the insulation. This test also establishes a benchmark for future comparative tests.
PD defined is a localized dielectric breakdown within a small portion of an electrical insulation system under stress of high voltage, which does not bridge the space between two conductors. Partial Discharge is not yet a complete failure of the insulation, however, it is an indication of what is to come. PD testing determines the presence, and locates PD activity within a system.
Sweep Frequency Response Analysis is a powerful method to measure and evaluate the mechanical integrity of a power transformer’s core, winding, and clamping structures by measuring their electrical transfer functions over a wide frequency range.
Dissolved Gas Analysis
The DGA is one of the easiest, most convenient test that can be performed on a power transformer, yet it is one of the most important. DGA determines the health of a transformer’s insulating oil.