The 400/200kV Siot substation coming up in UT of Jammu & Kashmir, as part of an interstate transmission scheme, will now use GIS technology instead of AIS planned earlier.
In its latest meeting, National Committee on Transmission (NCT) approved the GIS (gas insulated switchgear) configuration as it would address the topographical challenges that the AIS variant would have posed.
It is learnt that the land on which the substation is proposed to come up has significant terrain level difference of as much as 60m. Besides, the site has a deep valley on one side, which would necessitate extensive wall construction. Potential bidders had expressed their apprehension over these topographic difficulties, citing consequences like higher construction risk and civil works cost. Bidders also pointed out to delay in mobilization of equipment, in turn leading to delay in project commissioning.
In normal course, the cost of a GIS substation is much higher than AIS. However, deliberations led to the conclusion that considering the huge civil work involved in the AIS configuration, GIS would in fact be a cheaper alternative, at least in this case.
Bid process coordinator PFC Consulting Ltd (PFCCL) has been directed to go ahead with the bidder selection process, incorporating this critical change in the bidding documents. The project now termed as “Creation of 400/200kV, 2×315 MVA (GIS) substation at Siot, Jammu & Kashmir,” also involves a 15-km LILO of the existing 400kV double-circuit Amargarh (Kumzer) – Samba line, at the upcoming Siot substation.
Saga of delays
The Siot substation scheme was approved by NCT in August 2021 and bidding was initiated in February 2022. There were multiple postponements of the pre-bid meeting and extensions in bidding submission dates, due to delays in land finalization. It may be noted that land for the Siot substation was finalized in January 2023 as the tentative sites proposed earlier —including one at Bakhar village, Rajouri — were found technically infeasible.
In early 2023, Bidding was put on hold as J&K Power Transmission Corporation Ltd (JKTPCL) could not finalize the downstream intrastate system on time. Bidding resumed in January 2025 but the process is expected could get prolonged due to the AIS-GIS change discussed in this story.
It may be mentioned that the upcoming Siot substation would be feeding power to downstream intrastate substations like Rajouri, Akhnoor and Katra. Incidentally, PFCCL is the bid process coordinator for the intrastate system, which is also coming up under the TBCB model.
PFCCL, as the common BPC for both the interstate and the downstream intrastate Siot schemes, is expected to ensure that they are commissioned in a matching timeframe.
GIS vs AIS
In a recent interaction with tndindia.com, Kurang Panchal, Managing Director, Rajesh Power Services Ltd, while discussing the difference between AIS and GIS substation from the contractor’s perspective, explained that while AIS substations at more land- and logistics-intensive, GIS substations are execution- and precision-intensive. (Read full interview)
Also read: GIS versus AIS: NCT to deliberate
Featured photograph (source: Rajesh Power Services Ltd) is for representation only