● Tan delta/Power factor/dissipation factor/capacitance (@ line frequency): Tan delta/power factor/dissipation factor assesses the integrity of the insulation system of the bushing. C1 and C2 tests should be performed on a capacitance-graded bushing. A C1 power factor/dissipation factor test checks the health of the bushing’s main core insulation, while the C2 measurement is used to assess the bushing tap compartment’s insulation plus the outermost main core insulating wraps and surrounding filler material. Often, C2 serves as early detection for moisture ingress or other contaminants that collect around the flange area because of a deteriorated or faulty top terminal gasket, for example.
● Capacitance: measured concurrently, assesses the physical integrity of the bushing. An increase in C1 capacitance for example may indicate short-circuited capacitance-graded layers in the bushing, a diagnosis which warrants the bushing’s immediate replacement.
● Tan delta/Power factor/dissipation factor tip-up: Tan delta/power factor/dissipation factor tip-up (which checks to see whether power factor/dissipation factor changes when the test voltage changes) may be useful in the detection of loose connections or localized defects; may be effective in detecting aging effects when combined with DFR. Ask us how…
● Variable frequency power factor/dissipation factor (VFPF): This test is a collection of power factor/dissipation factor measurements performed across a subset of the frequencies included in a DFR measurement (e.g., 15 – 500 Hz). Conductive contaminants are easily seen at low frequencies (15 Hz and below) while problems such as top terminal looseness and PD inducing type issues may be detected at higher frequencies (500 Hz).
● Hot collar test: A hot collar test is used routinely for solid type bushings without taps and is effective in revealing deterioration, contamination, low compound or liquid levels, and voids in the compound (if applicable). It may also be effective as a supplementary test to C1 and C2 tests on capacitance-graded bushings with taps.
● Dielectric frequency response (DFR): In bushing diagnostics, a pronounced temperature dependence (i.e., increased power factor/dissipation factor at high temperatures) is a strong indicator of bushing insulation deterioration. DFR measurements provide the capability of performing individual temperature correction of measured 50/ 60 Hz power factor/dissipation factor at various temperatures to values at a reference temperature (20ᵒC). Comparing this measured temperature dependence with the bushing manufacturer’s data for temperature correction will tell if the bushing is good or not. DFR measurements can be used for moisture assessment of bushings.
● Partial discharge (PD)
● DGA: some asset owners sample oil from a capacitance graded bushing for the purpose of performing dissolved gas analysis tests. This is not a popular practice.
We are offering high quality Transformer Bushing that is utilized on the transformers as the primal lead entrances. It consists of high-grade porcelain cylinders which conductor move through. The outside surfaces of this bushing can boost the leakage path length to the grounded metal case. Provided high-voltage bushing is specifically oil-filled condenser type, rendered with a central conductor wound with alternating layers of paper insulation as well as tin foil and occupied with insulating oil. The power factor of Transformer Bushing in great condition will remain comparatively stable throughout the service life. The bushings are mostly employed in high voltage transformers and serve to end the transformer's interiors. These are commonly employed in applications orbiting from small distribution transformers as well as circuit switchers to large setups.