Shanthala Power Research Corporation

OFFLINE MEASUREMENTS:

1. Condition Monitoring Tests on Transformers:

Sl. No.	TESTS	INFORMATION PROVIDED BY TESTS
1	Insulation Resistance (IR)	Indicates the dryness and cleanliness of winding.
2	Polarization Index (PI)	It is a direct measure of dryness of winding.
3	DC Absorption Test	Indicates insulation condition of the winding.
4	Capacitance & Tan Delta Test	Indicates dielectric loss in the insulation.
5	Leakage Current Test	It helps in prediction of break down voltage.
6	Furan Analysis Test	Indicates deterioration of paper insulation.

b) Tests on Transformer Conductor and OLTC:

Sl. No.	TESTS	INFORMATION PROVIDED BY TESTS
1	DC Winding Resistance	Loose connection in the winding or in OLTC.
2	Ratio Test and Phase Angle Error Test	Indicates connection of the tapping leads & loose connections turn short within the winding.
3	Floating Neutral Point Measurement	Indicates connection of common point.

c) Tests on Transformer Core:

Sl. No.	TESTS	INFORMATION PROVIDED BY TESTS
1	Excitation Current Test (at High Voltage)	It conforms the turns ratio of transformer.
2	Magnetic Current Test	To check the imbalance in the magnetic circuit.
3	Magnetic Balance Test	To check the imbalance in the magnetic circuit.
4	Frequency Response Analysis (FRA)	FRA is used to detect condition of core end winding based on the previous references, which is created as database. This also clearly shows the winding being buckled turn shot and failure of insulation to some extent. Benchmark records should be made available for analysis and recommendation.

d) Tests on Transformer HV Bushings:

Sl. No.	TESTS	INFORMATION PROVIDED BY TESTS
1	Capacitance & Tan Delta Test	Indicates the healthiness of bushing.

e) Tests on Transformer Oil: (OLTC/Top/Bottom):

Sl. No.	TEST	INFORMATION PROVIDED BY TESTS
1	Interfacial Tension	Indicates the presence of sludge and excessive polar contaminants from the cellulosic materials.
2	Neutralization Number	Indicates the acid contents in the oil.
3	Moisture Content	Indicates the total dissolved water in the oil.
4	Flash Point	Indicates the presence of some of the lower hydro -carbons.
5	Sludge	Indicates deposition of fibrous particles, dust, contaminants etc.
6	Dielectric Dissipation Factor	Indicates the contents of contaminants like soluble varnish, resins and other polar contaminants. Ageing of Oil.
7	Resistivity
8	Dielectric Strength	Conductive contaminants present in the oil such as metallic cuttings or free water.
9	Kinematic Viscosity	Indicates that heat removal efficiency of oil.
10	Pour Point	Indicates freezing point of oil.
11	Density	Indicates heat dissipation characteristics.
12	Dissolved Gas Analysis Methane Ethane Ethylene Acetylene Oxygen Nitrogen Carbon Dioxide Carbon Monoxide Hydrogen Total Gas Content	Laboratory tests revealing ppm of combustible gas. It is powerful diagnostic preventive maintenance technique for monitoring internal condition of the transformer.
13	Furan Analysis	Indicates deterioration of paper insulation.

Design And Developed By
Trinity Inc