FIELD OF INVENTION
The present invention relates to the development of a test set-up for three phase
common enclosure type gas insulated switchgear, particularly to high voltage testing of
three phase common enclosure type GIS bay and gas insulated bus duct.
BACKGROUND OF THE INVENTION
Gas insulated substation is exclusively intended for switching and distributing electrical
power, comprising electrical bus bar, isolator or disconnector, circuit breaker, current
transformer, voltage transformer, earthing switches, surge arrestor or lightning arrestor
which call for quality tests at each stage of manufacturing up to the final assembly and
commissioning at site, which involves a considerable time to undertake such test
procedure making the process very costly. In view of that a novel means of conducting
tests are under way of development through this invention under reference.
DESCRIPTION OF THE PRIOR ART
Conventionally, each phase of a three phase GIS has to be connected to voltage
generator independently to evaluate the withstand capacity for a specified high voltage
both at manufacturing unit and at site before commissioning. This method of testing

takes a long time and may not be economical. Earlier the testing was conducted on
sub-assembly of GIS which involves preparation of test set up, assembly of test
fixtures, alignment of components with the test kit etc. requiring a significant time for
testing at manufacturing unit and at site. In order to reduce the time to arrange the
assembly of GIS equipment for testing and waiting time/off time for high voltage tests
to be conducted on multiple phases, a novel arrangement has been proposed. The
proposed arrangement shall accommodate testing of three phase compact GIS in a
single go with minor assembly changes.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention is described with the help of Figures 1 to 7, where,
Figure 1: shows the conventional testing of three phase GIS bay.
Figure 2: shows the compact three phase bus bar assembly.
Figure 3: shows Terminals of connection between GIS and voltage generator with
shield.
Figure 4: shows three phase terminals of varying lengths
Figure 5: shows the novel interface unit proposed.
Figure 6: shows the novel profiled high voltage connector.

OBJECTS OF THE INVENTION
The basic object of the invention is to reduce the assembly preparation time of
individual modules for testing of gas insulated substation in addition to reduction of
time for assembly of GIS bay during multi phase testing.
A further object of the invention is to reduce evacuation and gas filling time of GIS
during multi phase testing.
Yet another object of the invention is to reduce the commissioning time of GIS.
DETAILED DESCRIPTION OF THE INVENTION
A special interface unit has been devised to integrate the single bay of GIS to the high
voltage test kit or voltage generator to be used for testing the circuit breaker, bus bar,
disconnector switch and earthing switches of different possible configurations. The
connection for each phase is done with a special fixture developed to conduct high
voltage test for one phase at a time.
1) In the proposed arrangement an interface unit has been developed to integrate
three phase compact GIS BUS bar (refer Fig. 2) with the single phase generator,
comprising interface unit of a single phase conductor with suitable support of cone

insulator. Each terminal of compact GIS bay is extended from the bus bar to the
interface unit and the profiled connector is coupled to a particular phase of testing
(Fig. 3). The length of terminal changes from one phase to another depending on
configuration of phases (Fig. 4). The interface unit is designed in such a way that
one side it is directly coupled to voltage generator and other side it is connected to
the bus bar phase to be tested (Fig. 5). The high voltage conductor is connected to
each phase of three phase compact GIS bus bar through a novel profiled connector.
The high voltage connector shall withstand all high voltage duties and the
electrostatic field around this connector which is well below the critical levels (Fig.
6). The proposed method of testing of each phase is also suitable to compact gas
insulated bus duct wherein all the three phases are in a single enclosure. The
terminal to be tested and unused terminals shall be separated with an insulated
guard shield to avoid inter phase spark over.

WE CLAIM
1). An interface module to connect all the three phases of GIS bay to high voltage
generator, characterized by fast change over from one phase to the other and
connection to the generator.
2) The module as claimed in claim 1, wherein, a high voltage profiled connector to
connect all the three phases of GIS bay.
3) The module as claimed in the preceding claims, characterized by three phase
terminals of unequal lengths with necessary shields for ease of connections.
4) A method of testing of each phase of compact GIS, one phase at a time, wherein all
the three phases are in a single enclosure.
5) A method of testing of each phase of compact gas insulated line, one phase at a
time, wherein all the three phases are in a single enclosure.