UHV Laboratory at BHEL is one of the largest electromagnetically screened laboratories in the world and offers the most modern and sophisticated testing facilities for a wide range of transmission equipment and products. The laboratory is designed essentially for comprehensive testing of power transformers and shunt reactors. The impulse test plant and AC high voltage test plants are adequate for test levels appropriate upto 1100 kV transmission systems. The AC power test plant is suitable for performing test on equipment up to 800 kV class with provision of enhancing the capacity in future for conducting tests on 1100 kV equipment. The DC test plant is adequate for test levels suitable up to + 800 kV HVDC transmission systems. 

With the above facility, performance testing of 315 MVA three-phase transformers; 200 MVA single-phase transformers; 80 MVAR shunt reactors for 400 kV AC systems, 315 MVA, + 500 kV DC single-phase converter transformers and 800 kV bushings & CVTs have been satisfactorily established in laboratory.

	Internal clear dimensions of 67 m (L) x 35 m (W) x 35 m (H)
	All double wall GI construction with electrical continuity, false roofing and embedded earth copper mesh provides a complete Faraday cage (electromagnetic shielding).
	Acoustic attenuation with reverberation time of 3 to 3.5 seconds in the desired frequency range.
	Low impedance grounding system.
	Special floor for smooth air-cushion transport.
	Air cooling and ventilation system to control ambient variations during temperature rise test.
	Discharge-free halogen lamps for illumination.

	A pollution test chamber measuring 15m (L) x 15m (W) x 20m (H) is located adjacent to the main test hall for conducting wet and pollution tests. Voltage to the test object in the pollution chamber is applied for the main test hall through a 750 kV wall bushing.
	On the southern side of the main hall, a transformer and reactor room houses interposing testing transformers, reactors and measuring current & voltage transformers for power frequency tests.
	A 100 MW Ar, 156kV, 3-phase capacitor bank with provision for augmentation unto 120 MVAr, installed outdoors, enables conducting of load loss measurement and temperature-rise test on transformers and reactors.
	Apart from the main hall, an open test are has been left for the future, when it will be necessary to conduct testing at higher test voltages.

A. TESTS AC TRANSFORMERS & SHUNT REACTORS 

	Impedance, loss and temperature rise tests
	Separate source voltage withstand test Induced over voltage withstand test
	Partial discharge measurements
	Lightning impulse full and chopped wave tests
	Switching impulse tests, Other Routine and Type Tests
	Special Test on Reactors

	Vibration and stress measurement.
	Measurement magnetization characteristics.

B. TESTS ON DC CONVERTER TRANSFORMERS & SMOOTHING REACTORS

	Long duration DC voltage test DC polarity reversal test with partial discharge measurement
	Temperature rise test with DC voltage supply
	Lightning & switching impulse tests
	AC power frequency test
	Loss measurement.

C. TESTS ON BUSHINGS

	Tan-delta & Capacitance measurements
	Partial discharge & RIV measurements
	Dry and wet power frequency dielectric tests
	Lightning and wet switching impulse tests
	Thermal stability test
	Dielectric tests with DC application, Snap back test

D. TESTS ON INSTRUMENT TRANSFORMERS

	Partial discharge and RIV measurements
	Dry and wet power frequency dielectric tests
	Lightning and switching impulse tests
	Transient & Ferro-resonance tests
	Fast transient test.

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