The document describes a high voltage laboratory, including: 1. It provides test facilities for equipment like transformers, arresters, insulators, cables, and capacitors. 2. The main purposes are testing equipment and conducting research on topics like breakdown strength of materials and high voltage power systems. 3. It classifies high voltage labs as small, medium, or large depending on voltage and space requirements. Large labs can test and research equipment up to 800kV and above and include multiple test halls and outdoor areas.

2.  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.  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
.

5.  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. Type of
h.v. lab
Small
lab
Medium
lab
Large
lab

7. Small size lab
 Voltage rating
 Equipment rating :
< 10kva/10KW
 Impulse equip.:
< 10KJ energy
 size
 Size for room may be
15mx10mx8m
 Sometimes 5m x 8m only
 Used by
 Mostly used by colleges and universities..

8.  Main function is to do routine test
 Voltage rating: 200 kv to 600 KV
 KVA rating: 100 to 1000
 Planning of such lab include
 Ground transport
 Handling equipment like cranes
 Rationalization of test procedure by making instrument easily accessible
 Extension facility for future
 impulse generator rating:
 More than 10 to 20 KJ
 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 .
 In industrial laboratories not much emphasis is generally given
for undertaking research work and little flexibility may be
available for incorporating new equipments

9.  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).

10.  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

11.  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
SIZE AND RATINGS OF LARGE SIZE
HIGH VOLTAGE LAB

12.  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

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

15. 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.

16. 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.

17.  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.

18.  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.

19.  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. 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
Other High Voltage Testing
Equipment

22.  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.

23.  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.  It is based on type of equipment to be tested , available
space ,
other accessories needed for the tests……
 EARTHING and SAFETY is foremost consideration
……

30. Impulse Voltage Generator
600 kV , 18 kJ

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

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