Prefabricated Substation (PSS)

Prefabricated Substations are Substations (as the name suggests) that are assembled as complete compact unit with incoming HT breakers,HT bus section outgoing breakers transformers,LT incoming circuit breakers LT bus section and outgoing Circuit Breakers and protective relays.They can be housed in compact weather proof roofing also to enable out-door installation.

All components are fabricated on single frame that can be transported to any site or building and can be installed with out technical expertise at site by terminating HT and LT cables directly with in short span of time.Unlike conventional substations it do not have provision for modification for expansion. The complete load details and power requirements must be known in advance for the design and fabrication of pre fabricated substations. the advantages are its compactness and easy installation.Mostly Dry type transformers and VCB and ACB are preferred for this design. OCB and oil filled transformers are not suitable for such compact designs.

Thanks for you answer and the same was very clear. can you give what all preventive maintenance has to be done regularly to avoid any breakdown of PSS. can u expain abt the dry type transformers and difference / advantages from conventional oil type transformer and the maintenance part.

As explained earlier, in a nutshell PSS is collection of various electrical equipments with interconnections within enclosure.There is no much of difference in maintenance of these electrical equipments compared to conventional equipments.

As regards dry type transformer ,air is the cooling medium instead of oil.Therefore therewill not be any oil temperature sensors,However there should be temperature sensors embedded in the winding.

Mr V.I Abraham has already explained.

One additional information is It is also called as Unitised Substation.This will have one HT Incomer and fixed number of LT outgoings.There will not be scope for expansion and modifications.Will be useful for Projects and can be shifted from Project to Project.

Good n precise info has already been given by Abraham and Ram. Since, technically there is no major difference ( leave aside expansion etc. ) between PSS/unitised and conventional subs-station therefore there is no special requirement of maintenance. This

trend, generally for 11kV/33kV, is catching up since the substation can be built & tested in the factory factory. The customer, practically needs to only draw the line/cable from the source and use it for consumption.

Thanks and regards

Ashok Toshniwal, Bangalore, India

Well, Can we bring GIS in PSS category?