1. High voltage engineering
Need for future………………

2. Design, Planning and Layout of
high voltage laboratory
• Test facilities provided in high voltage lab
• Activity and study in high voltage lab
• Classification of high voltage lab
Our main aim to study is:

3. Why to study these topics?????
• In this industrial developing world the need of power is increasing
exponentially
thus to transfer high power at long distance is necessary
• So the transmission at h.v is possible which is up to 720 kv and 1000kv
• So extensively study is made on high voltage d.c. testing at 400 kv
• Thus to perform tests and research
the lab providing high voltage is needed

4. • Transformers
• Lighting arrester
• Isolator and C.B
• Different type of insulators
• Cables
• Capacitors
• Line hardware and accessories
• Other equipment like reactors
.
Test facilities provided in high voltage lab

5. Activities and studies in high voltage laboratory
• Main is testing on equipment
• Other than it is research
• So research include
i. Breakdown strength of different material like
solid ,liquid and gas.
ii. Electrical interference of transmission line
iii. High voltage power system’s insulation
iv. High current phenomena such as electrics arc and plasma physics

6. classifications
Type of
h.v. lab
Small
lab
Medium
lab
Large lab

7. Small size lab

8. Medium size lab: an industrial lab
In industrial laboratories not much emphasis is generally given for undertaking research work and little flexibility may be
available for incorporating new equipments
Other test equipment like the impulse current generator for testing surge diverters and d.c. test facilities for testing cables and
capacitors can also be made available .
impulse generator rating:
More than 10 to 20 KJ
Planning of such lab include
Ground transport Handling equipment like cranes
Rationalization of test procedure by
making instrument easily accessible
Extension facility for future
Main function is to do routine test
Voltage rating: 200 kv to 600 KV KVA rating: 100 to 1000

9. Large size lab
Used for testing and
research work
It contains facilities like
• One or more h.v. test halls,
• Corona and pollution test chambers,
• Outdoor test area for tests on large sized
equipment, transmission lines and towers
etc.,
• Controlled atmospheric test
rooms/chambers,
• Computer facilities, library etc. with good
office facilities, and Provision for
overnight tests and stay.
The building and
equipment include the
workshop, material
handling equipment
like cranes, ladders, air
cushion platforms etc.
and large control and
electric supply facilities
(up to few KVA or
MVA).
such a laboratory will
include a director or
manager, few group
leaders, and section
heads separately for
research, testing,
measurements,
electronics and computer
facilities
The cost of
such
laboratories
will be several
millions of
rupees

10. HIGH VOLTAGE LAB

11. SIZE AND RATINGS OF LARGE SIZE HIGH VOLTAGE LAB
Withstand Voltages,
Test Voltages and
the Rating of
Equipment in High
Voltage
Laboratories
Voltage and Power
Ratings of Test
Equipment
Size and
Dimensions of the
Equipment In High
Voltage
Laboratories
Layout of High
Voltage
Laboratories

12. Large size high
voltage lab

13. Withstand Voltages, Test Voltages and the Rating
of Equipment in High Voltage Lab
• Generally up to 230 KV design it does not pose any problem but above 400
KV it is to be handle with care
• For research and development work, the voltage levels needed are usually
about 1.3 times the maximum test voltage needed. Hence, the laboratories
intended for different system voltages should have the test voltages

15. Voltage and Power rating of test equipment
1. D.C. Testing Equipment
2.Power frequency testing equipment
3.Impulse generators
4. Other hv testing equipment

16. D.C. Testing Equipment
It can be performed with cascaded rectifier.
When testing polluted insulation intense care must be taken
It require currents of 50 to 200 mA, but strong pre-discharge streamers
of 0.5 to 1.0 A of milliseconds duration may occur.
Hence, the generator must have adequate internal reactance in order to
maintain the test voltage without too high a voltage drop.

17. Power Frequency testing equipment
The flashover voltage of an insulator in air or oil or in
some fluid depends on the capacitance of the supply
system, due to the fact that a voltage drop may not
maintain the pre-discharges before breakdown.
Hence, a minimum of 1000 pF or more in parallel with the energized
insulator is needed to determine the real flashover or puncture voltage,
and the generator has to supply at least 1A in the case of clean and 5 A
in the case of polluted insulator at test voltage on short circuit.
The output of testing
transformer will be given by
• p = 2ΠfC x V² x 10e-19 KVA
Transformer self capacitance
ana capa. Of various high
voltage e.g. bushing is used
to measure load capac.

18. • The maximum charging voltage of an impulse voltage generator is given by the
stage voltage multiplied by the number of stages. The peak value of the impulse
voltage V5 for a standard 1.2/50 ^s wave is
•
V d.c. = Charging voltage,
• n = number of stages in the generator,
• CL = load capacitance, and
• Cg = generator capacitance.
Impulse Generators

19. • In order to test transformers which have large capacitance, a minimum of 30,000 to
40,000 pF of generator capacitance is needed.
• A simple calculation will show that a minimum of 135 KJ is required for a 3 MV impulse
generator, if the IEC specification for impulse wave shape is to be maintained.
• The minimum energy rating of a 6 MV impulse generator will be about 600 kJ.
• From this it may be concluded that the energy rating in kilojoules may be approximated
to be equal to 0.1 times the voltage rating in kV.
• There is no problem to pile up a large size capacitance in the form of a number of
capacitors and to charge them in parallel and discharge them in series to give the
requited peak of the standard impulse wave.
• But many difficulties exist in reducing the internal inductance of the circuit to a minimum
to obtain a steep front and to avoid oscillations. As an example, a 4 MV impulse generator
test circuit has a length equal to 0.1 times the voltage rating (kv)
• Hence, a very careful design and a very careful consideration of the test circuit only can
give the optimum test conditions which are not far from theoretical specifications

20. IMPULSE GENERATOR

21. Other High Voltage
Testing Equipment
Usually, the other testing equipment that will be available is, 1. impulse current generators for testing lightning arresters,2. test facilities for
measuring RIV and partial discharges, 3. sphere gaps for measurement and calibration purposes, and 4. high voltage Schering bridge for
dielectric testing.
Usually, the impulse current generators are rated between 100 to 250 kA with an energy rating of 50 to 100 kJ.
This is more than adequate for testing with lightning stroke currents.
Partial discharge and RIV measurements require testing transformers free from internal discharges. The detection equipment should be
capable of detecting 0.01 PC of charge in at lest object capacitance of 100 pF and 2 to 3 PC
Thus , test transformers should have internal discharges of the same order at the specified voltage value.
it is possible to design a.c testing transformers with necessary shielding, etc. with internal discharges less than 5 pC at 50OkV.
Where sphere gaps are used, it is important to bestow thought regarding the proper size and space requirements. Proper attention must be
given to type and magnitude of the voltage to be measured, range of operation keeping in view that the sparking distance is less than 0.5
times the diameter of the spheres, and space requirements as specified in IS: 1876-1961 and other specifications

22. Control panel of
high voltage
testing instrument

23. Size and Dimensions of the Equipment In High
Voltage lab
• Mainly two type of lab:
1. indoor type & 2.outdoor type
• indoor type has the advantage of
1. protection of testing equipment against variable weather conditions,
2. simplicity in design and control of the test equipment,
3. provision of observation facilities during testing.
• outdoor laboratories have the advantage of
1. less cost due to the absence of building cost and
2. the planned facility
3. layout cost
• But it has disadvantages
1. absence of lifting and supporting facilities,
2.climatic conditions which may restrict or impede testing
3.reproducibility of results not being guaranteed due to uncontrolled
atmospheric conditions, and
4.artificial and wet test studies which are difficult due to wind variation, etc.

24. • When high voltage laboratories are planned as indoor laboratories, the
following figures fix the dimensions of the laboratories:
1. Size of the test equipment for a.c., d.c., or impulse generators
2. Distances or clearances between the test object and ground during test
conditions and also between all the high voltage terminals and earthed or
grounded surroundings such as walls, roofs of buildings, and other test
equipment not energized.

25. Layout of high voltage lab
• It is based on type of equipment to be tested , available space ,
other accessories needed for the tests……
• EARTHING and SAFETY is foremost consideration ……

26. Labbuilding

27. High voltage lab in India

29. Impulse Tests on Transformers
Impulse Voltage Generator 600 kV ,
18 kJ

30. Automatic HV and PD measuring systems for testing of bushings for SF6 switchgears
Complete High Voltage Test Systems

31. Complete High Voltage Test Systems
Specific test systems for different applications, like
• surge arresters
• switchgears

32. DONE BY: NIDHI MARU