Technology Literature

The Harm of Partial Discharge of Transformer

When the transformer generates partial discharge under the working voltage, even a very weak discharge will cause corrosion to the insulating material. In the long run, the accumulation effect will affect the dielectric property of the insulation, causing the insulation to deteriorate until the insulating layer is finally broken. The chemical elements generated during the discharge process will accumulate on the solid insulation, which further excites the discharge of electrical equipment, and it is easier to break through the insulation in areas with high field strength and insulation damage. And eventually form a carbonized layer through the insulation

One of the causes of transformer failure is dielectric breakdown, which is mainly caused by partial discharge, which causes insulation deterioration and even breakdown. With the development of transformer fault diagnosis technology, people gradually realize that partial discharge is the root cause of many faults and accidents of transformers, so the test of partial discharge is getting more and more attention. In recent years, 50% of power transformer accidents above 110kV are caused by inter-turn short circuit under normal operating voltage, and also caused by partial discharge. Therefore, partial discharge measurement has been taken as one of the important projects for 220kV transformer handover and overhaul. Condition monitoring and troubleshooting will be very effective.

Through the discussion of transformer-related tests, we can see that in the handover test, the relevant test of the transformer is the inspection of the overall insulation of our transformer.

Only by conducting an effective insulation test on the transformer can we judge whether the insulation of the transformer meets our operational requirements. This is the main means by which we can judge whether the transformer can be put into operation.

The test items are required for 110kV/220kV substation acceptance and maintenance testing(with corresponding tester types):

Test Object	Testing Item	Tester Type
Cable	Cable AC Hipot Testing	JYCX	Details
Cable	Cable Insulation Resistance Testing	JYM KYORITSU	Details
Transformer	Insulation Resistance of Winding	JYM KYORITSU	Details
	DC Leakage Testing in 1min	JYDHV	Details
	Winding Resistance Testing	JYR50S	Details
	Winding Deformation Testing	JYP	Details
	Turns Ratio Testing	JYT-A	Details
	AC Hipot Testing	JYCX	Details
	Short Circuit Impedance Testing	JYW6300	Details
	Dan Delta Testing	JYC	Details
	Oil Breakdown Voltage (BDV)Testing	JY6611	Details
	Oil Tan Delta Testing	GTD-61A	Details
Switchgear	Circuit Breaker/Disconnector Resistance	JYL-200B	Details
Relay	Relay Performance	JY7003G	Details
On-load	On-load Switchgear Testing	JYK-I	Details
On-load	Tap Changer Dynamic Testing	JYK-I	Details
Instrument Transformer	Current Transformer (CT)Testing	JYH-C	Details
Instrument Transformer	Potential Transformer (PT)Testing	JYH-C	Details
Surge Arrestor	Zinc Oxide Characteristics Testing	JY6800	Details
Surge Arrestor	1mA DC Reference Voltage	JYDHV	Details
Capacitor	Capacitor Current	JY6700	Details
Capacitor	Capacitor Inductance	JY6700	Details
Ground Grid	Grounding Down Lead Earth	JYD	Details

Related Articles:

What Test Items are Required for 110kV/220kV Substation Acceptance and Maintenance Testing?

What Tests Must be Done before the Transformer Leaves the Factory?

Main Factors Affecting the Operating Life of Transformers

What is the Purpose of Measuring the DC Resistance of the Transformer Winding?

Points to note in transformer oil breakdown voltage (BDV) test

DC winding resistance tester with 500 times tests on a single charge -JYR9310

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