7500kva Oil Filled Transformer

•Oil immersed transformer use ester oil is that it is not flammable, superior fire safety
•Adopts Seven-step silicon steel lamination insulated on both sides, guaranteeing low losses and low noise
•Strong resistance to sudden short circuits
•Liquid immersed transformer adopt hot dip galvanized tank
•High-temperature resistant insulation system
•Waterproof, moisture-proof and salt spray-proof,
•Special design structure for seismic zones or for using in applications with high level vibrations.
•Marine coating C5-M withstand the most extreme environmental condition, Prevent oil leakage technology

Varelen manufactures heavy-duty 7500kVA oil-filled transformers with voltage ratings up to 35kV, featuring ONAN/ONAF cooling options and low-loss designs tailored for industrial grids and renewable substations.

Main Specification
Transformer Type	Oil immersed , Hermetically sealed (without conservator) or with conservator
Rated capacity	Up to 40MVA
Rated voltage	Up to 132kV
Frequency	50 or 60Hz
Phase	single phase or three phase transformers
Winding material	Copper or Aluminum
Tap changer	Off-load or on-load, (or different range on request)
Tapping	±2 x 2.5 % , ±5% (or different range on request)
Insulation class	A（105℃）， E (120℃）, B（130℃）
Temperature rise	60/65 ℃ or custom specification
HV & LV terminals	HV terminals: plug-in or porcelain bushings LV terminals: busbars or porcelain bushings On request: cable boxes according to client/manufacturer standard or norm (i.e BS) requirements
Vector group	Dyn11, YNd1d1, Yyn0, YNd11 etc.
Cooling	ONAN , ONAF, KNAN, KNAF etc.
Bushing	Ceramic insulators or epoxy resin bushings
Insulation level	11KV BIL 95KV 22KV BIL 150KV 33KV BIL 200KV
Ambient temperature	-45°C + 60°C
Altitude	5000M （on request）
Dielectric fluids	Mineral oil, Silicone, FR3 Oil, Midel etc.
Standard	IEC, AS, EN, IEEE/ANSI, GOST
Accessories	Lifting lugs, Bushing, Oil level gauge, oil filling valve, drain valve, winding temperature indicator, pressure relief valve, Tap changer Oil Thermometer, Buchholz-Relay,

Surface protection

One of our major quality commitment is to provide high-quality surface protection. C4 and C5 The coating (painting) type is chosen in accordance with the environmental conditions, considering the degree of pollution, humidity, etc. Zinc Spray / Hot dip galvanized tank, HV/LV cover and conservator may also be provided.

Vacuum Oil Filling for Purity : Each oil immersed power transformer is filled using a vacuum oil-filling process to eliminate moisture and air, maximizing dielectric strength and ensuring optimal thermal performance.

5000kva 66KV Transformer

For each transformer are prepared and issued a test report, in accordance with IEC 60076. except for routine tests, we also offer type tests and specialized tests to meet all customer requirements. We make what matters work for our customers in a safe and reliable way.

Varelen has launched online FAT plan for customers. Our factory can make acceptance testing ( either witnessed and on-line) in order to show all technical and quality requirements have been done before shipment.

Quality Certifications

Varelen fully meets ISO 9001, ISO 14001,and ISO 45001 certifications and standards. Our products meet GB, IEC, IEEE, NEMA, CSA, AS, GOST and other international and domestic electrical engineering standards including UL, CE, BV and EU.

7500kva oil immersed transformer

Routine test

Measurement of winding resistance
Measurement of voltage ratio and check of phase displacement
Measurement of short-circuit impedance and loss
Measurement of no-load loss and current
Dielectric routine tests
Tests on on-load tap-changers, where appropriate
Leak testing with pressure for liquid-immersed transformers(tightness test)
Tightness tests and pressure tests for tanks for gas-filled transformers
Check of the ratio and polarity of built-in current transformers
Check of core and frame insulation for liquid immersed transformers with core or frame insulation

Type test

Temperature-rise type test
Dielectric type tests
Determination of sound level for each method of cooling for which a guaranteed sound level is specified
Measurement of the power taken by the fan and liquid pump motors
Measurement of no-load loss and current at 90% and 110% of rated voltage

Special Test

Dielectric special tests
Winding hot-spot temperature-rise measurement
Determination of capacitances windings-to-earth, and between windings
Measurement of dissipation factor(tanδ) of the insulation system capacitances
Determination of transient voltage transfer characteristics
Measurement of zero-sequence impedance(s) on three-phase transformers
Short-circuit withstand test
Measurement of d.c. insulation resistance each winding to earth and between windings
Vacuum deflection test on liquid immersed transformers
Pressure deflection test on liquid immersed transformers
Vacuum tightness test on site on liquid immersed transformers