purchase & stores division - ISRO

2.4 Relative Humidity
Maximum: 90%, Minimum: 30 %
Average Annual rainfall: 750mm
Average no of thunderstorm days/annum: 40
Altitude: 1000 M above S/L
Rainy months: June to November
The atmosphere is normal, laden with mild dust suspension during the dry months
and is subjected to fog in cold months Heavy lightening occurs in the area during
rainy months.
All equipments shall be designed to withstand seismic forces, corresponding to an
acceleration of 0.1g.
3.0 CODES AND STANDARDS TO BE FOLLOWED
The equipment shall comply with the requirements of latest revision of following
standards issued by BIS (Bureau of Indian Standards), unless otherwise specified.
IS Code Description
IS 3427: Metal enclosed Switchgear and Control gear for voltages above
1000 v but not exceeding 11000 v.
IS 9046 Ac conductors of voltage above 1000V up to and including
11000V.
IEC:466:1987
:IS:14659
AC Insulator –enclosed Switch gear Control gear for rated
voltages above 1KV and up to and including 38KV.
IEC:694,1980:
IS:12729
Common clauses for high voltage Switch gear and Control gear
standards.
IEC: 529:1989: Degree of protection provided by enclosures(IP code).
IS: 12063
IS 722: Integrating meters.
IS 1248: Electrical indicating instruments.
IS 2071: Methods of high voltage testing.
IEC:129 AC Switches and Earthing Switches.
IEC:801 Monitoring and Control.
IS:13118 / High voltage AC circuits breakers.
BS 5311
IS/BS:5463: High Voltage Switches.
IS/BS:5227 Metal enclosed AC Switch gear.
IS/BS 5463 High Voltage switches
IEC 298 BS MV metal-enclosed / Switchgear
5311
IEC 265 MV switches,
IEC 56 MV AC circuit breakers,
IEC 801 Monitoring and control
SECONDARY WIRING
Specification : HFFR unilay, pre twisted single core multi strand electrolyte
grade, annealed copper cable,
Page 10 of 23