It is continuation of our previous blog for revision in IS 1180, now we wish to give some summary points for revision in IS 1180 which will be useful for us to right selection of transformer, some of the points are as below:
a) IS 1180 has been completely revamped and revised.
b) Previously IS 1180 is only applicable upto 11KV 3 Phase 100KVA distribution transformer, now the scope of same has been enhanced and now it is applicable upto 2500KVA 33KV & 11KV transformer and scope is also extended to single phase transformers also.
c) Now losses are defined by Energy Efficiency Level 1, Energy Efficiency Level 2 and Energy Efficiency Level 3 and specified losses are inline with BEE’s Star 3, Star 4 and Star 5 upto 200KVA.
d) Losses for 250KVA to 2500KVA transformer are as per ECBC 2009 guidelines in which losses at 100% load are much lower than ECBC guidelines. In some rating losses at 100% load are reduced by 10%.
e) For 400KVA transformer losses at 50% load are reduced by 10%. For further capacities losses are same as per ECBC 2009 guidelines.
f) Minimum impedance has been increased i.e. 4.5% from 4% as provided in IS 2026 : 2011
g) Mounting dimensions are fixed upto 200KVA distribution transformer and upto 500KVA transformers wheels are not recommended.
h) Limits for Temperature rise for Top Oil and Winding have been decreased for the transformer of rating 250KVA to 2500KVA which are as below:
Top Oil: 40 Deg C
Winding: 45 Deg C 
i) Voltage Range 22KV and 33KV added and losses for 3 Phase can be extrapolated by following clause:
a) For transformers having voltage class above 11KV and upto and including 22KV, the permissible total loss value shall not exceed by 5% of the maximum total losses values specified for 11KV transformers.
b)  For transformers having voltage class above 22KV and upto and including 33KV, the permissible total loss value shall not exceed by 7.5% of the maximum total losses values specified for 11KV transformers.

j) Losses details for 11KV Single Phase Transformers added in revised IS 1180 and losses can be extrapolated for 22KV and 33KV also by following clause:
a)) For transformers having voltage class above 11KV and upto and including 22KV, the permissible total loss value shall not exceed by 7.5% of the maximum total losses values specified for 11KV transformers.
d) For transformers having voltage class above 11KV and upto and including 22KV, the permissible total loss value shall not exceed by 10% of the maximum total losses values specified for 11KV transformers.
Losses details for 11KV three phase transformers and single phase transformers are already mentioned in our previous blogs. 
  
In revised IS 1180 there are also inclusion of the specification for corrugated type transformers. We appreciate the BIS & Government of India for taking this step. It will be a great tool for us to serve the nation by saving energy. SAI Electricals already has models HEFF for Level 1 and shortly will come up with models of transformers for Level 2 & Level 3.
In case any enquiry free feel to contact us at info@saielectricals.com