HIGHLIGHTED POINTS FOR IS 1180 (Part 1) : 2014

To improve the efficiency of our electrical system recently Bureau of Indian Standards has taken some major steps to improve the electrical network of our country and now from 1^st Feb 2016 distribution transformer is added in mandatory equipment list of BIS and to manufacturing the transformer manufacturer must be obtained the license from BIS for this BIS issued the Fourth revision of IS 1180 (Part1): Outdoor Type Oil Immersed Distribution Transformers upto 2500kVA, 33KV Specification. In which BIS have been mentioned some major changes in the specification of transformers, some of the major highlighted points are as below:

In revised IS, transformers have been divided in three categories, which are as below:

a) Three phase distribution transformers upto and including 200KVA

b) Three phase distribution transformers higher than 200KVA upto and including 2500KVA

c) Single phase distribution transformers upto and including 25KVA

In revised IS specification, losses for each rating for each category have been defined in three levels which are denoted by as follows;

a) Energy Efficiency Level 1,

b) Energy Efficiency Level 2

3) Energy Efficiency Level 3

In each level maximum losses (No Load Loss + Load Loss) at 50% load & 100% load have been specified for each rating in all categories. Losses in Energy Efficiency Level 1 is almost equal to ECBC 2009 guidelines.

In revised IS 1180 there are three energy efficiency levels and for each categories, maximum values of total losses have been defined on 50% load and 100% load. Losses & percentage value of impedance for different categories are as below:

a) Three phase distribution transformers upto and including 200KVA, 11KV Class

Sl. No.	Rating (KVA)	% Z	Energy Efficiency Level 1		Energy Efficiency Level 2		Energy Efficiency Level 3
			@ 50%	@ 100%	@ 50%	@ 100%	@ 50%	@ 100%
1	16KVA	4.5%	150W	480W	135W	440W	120W	400W
2	25KVA	4.5%	210W	695W	190W	635W	175W	595W
3	63KVA	4.5%	380W	1250W	340W	1140W	300W	1050W
4	100KVA	4.5%	520W	1800W	475W	1650W	435W	1500W
5	160KVA	4.5%	770W	2200W	670W	1950W	570W	1700W
6	200KVA	4.5%	890W	2700W	780W	2300W	670W	2100W

b) Three phase distribution transformers Higher than 200KVA upto and including 2500KVA, 11KV Class

Sl. No.	Rating (KVA)	% Z	Energy Efficiency Level 1		Energy Efficiency Level 2		Energy Efficiency Level 3
			@ 50%	@ 100%	@ 50%	@ 100%	@ 50%	@ 100%
1	250KVA	4.5%	1050W	3150W	980W	2930W	920W	2700W
2	315KVA	4.5%	1100W	3275W	1025W	3100W	955W	2750W
3	400KVA	4.5%	1300W	3875W	1225W	3450W	1150W	3330W
4	500KVA	4.5%	1600W	4750W	1510W	4300W	1430W	4100W
5	630KVA	4.5%	2000W	5855W	1860W	5300W	1745W	4850W
6	1000KVA	5.0%	3000W	9000W	2790W	7700W	2620W	7000W
7	1250KVA	5.0%	3600W	10750W	3300W	9200W	3220W	8400W
8	1600KVA	6.25%	4500W	13500W	4200W	11800W	3970W	11300W
9	2000KVA	6.25%	5400W	17000W	5050W	15000W	4790W	14100W
10	2500KVA	6.25%	6500W	20000W	6150W	18500W	5900W	17500W

c) Single Phase distribution transformers upto and including 25KVA, 11KV Class

Sl. No.	Rating (KVA)	% Z	Energy Efficiency Level 1		Energy Efficiency Level 2		Energy Efficiency Level 3
			@ 50%	@ 100%	@ 50%	@ 100%	@ 50%	@ 100%
1	5KVA	4.0%	40W	115W	35W	95W	30W	75W
2	10KVA	4.0%	70W	190W	60W	170W	55W	150W
3	16KVA	4.0%	95W	265W	82W	224W	63W	190W
4	25KVA	4.0%	125W	340W	110W	300W	95W	260W

Further to above it is also observed that IS 1180 are now also applicable for 22KV & 33KV class transformers, losses values for 22KV & 33KV class transformers shall be applicable as per below 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 mentioned in table a) & b) for three phase.

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 mentioned in table a) & b) for three phase.

c) 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 mentioned in table c) for single phase.

d)  For transformers having voltage class above 22KV and upto and including 33KV, the permissible total loss value shall not exceed by 10% of the maximum total losses values mentioned in table c) for single phase.

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