220kV Oil-immersed Power Transformer

Economic or deluxe solution optional Better cost performance IEC Standards Criteria New factory for better price NVTC/ OLTC

REFERENCES

ISO 1461: Hot dip galvanized coatings on fabricated iron and steel articles – Specifications and test methods.

IEC 60076: Power transformers.

IEC 60044: Instrument transformers.

IEC 60296: Specification for unused mineral insulating oil for transformers and switchgear.

IEC 60354: Loading guide for oil – immersed power transformers.

IEC 60214: Tap-changers - Part 1: Performance requirements and test methods, Part 2: Application guide.

IEC 60512: Connectors for electronic equipment.

Performance

220kV Two-Winding Power Transformer With NVTC/OLTC
Rated  Capacity  (kVA)	Rated Voltage  (kV)		Vector Group	Losses (W)		Impedance  Voltage  (%)
	HV	LV		No load	On load
31500	220 ±2×2.5%	6.3	YNd11	29000	135000	12-14
40000		6.6		35000	158000
50000		10.5		41000	189000
63000		11		49000	221000
90000		10.5		65000	288000
120000		13.8 11		80000	347000
150000		11		96000	405000
180000		13.8		109000	459000
240000		15.75		136000	567000
300000		15.75		160000	675000
360000		18		184000	774000

220kV Three-Winding Power Transformer With   NVTC/OLTC
Rated Capacity  (kVA)	Rated Voltage  (kV)			Vector  Group	Losses (W)		Impedance  Voltage (%)		Capacity Arrange (%)
	HV	MV	LV		No load	On load	Step Up	Step Down
31500	220 ±2×2.5%	69 121	6.3  6.6	YNyn0d11	34000	162000	HV-MV 22-24 HV-LV 12-14 MV-LV 7-9	HV-MV 12-14 HV-LV  22-24 MV-LV 7-9	100/100/100 100/50/100 100/100/50
40000			10.5  11		40000	189000
50000			35		48000	225000
63000			38.5		56000	261000
90000			10.5  11 13.8		73000	351000
120000			35 38.5		90000	432000
150000			11    13.8		106000	513000
180000			15.75    35		121000	585000
240000			38.5		149000	720000

 

 INSULATION LEVELS

Nominal system voltage (kV,   rms)	Highest system voltage (kV,   rms)	Lightning Impulse withstand voltage, dry (kV,   peak)	Power frequency withstand voltage, wet (kV,   rms)
33	36	200	95
132	145	650/750 (internal/external)	275/325 (internal/external)

AUXILIARY SUPPLIES

Equipment generally rated for the following auxiliary power supplies:

(a)          Cooler control circuits:          220V, 240 V, single phase, 50Hz

(b)         Tap changer control:              220V, 240 V, single phase, 50Hz

(c)          Cooling fan motors:               380V, 415 V, three phase, 50Hz

(d)         Tap changer motor:               380V, 415 V, three phase, 50Hz

 

 ROUTINE TEST to IEC 60076 (to be done during acceptance testing at factory)

• Measurement of winding resistance

• Ratio test

• Vector group

• Separate source voltage withstand test

• Induced over-voltage

• Insulation resistance

• Oil leakage test on fully assembled transformer for 12 hours

• Measurement of impedance voltage

• Magnetic balance

• Measurement of no-load loss and current

• Measurement of load loss (at normal & extreme taps)

• Tests on on-load tap-changer

• Tests on on-load tap-changer remote control panel

• Efficiency at 50%, 75%, 100% loading at unity p.f and rated terminal voltage (Corrected to 75C)

• Lightning impulse withstand test

Type Tests to IEC 60076 (to be done during acceptance testing at factory)

• Temperature rise test – To be performed on one unit during acceptance testing.

Lightning Impulse Withstand Test is already listed under Routine Tests as per IEC 60076.

Test Facility

Installation

220kV Oil-immersed Power Transformer