REVISION IN IS 1180: HIGHLIGHTED POINTS (PART II)

Recently Bureau of Indian Standards issued the Fourth revision of IS 1180 (Part 1): Outdoor Type Oil Immersed Distribution Transformers upto 2500 kVA, 33KV Specification. To discuss the various changes in design parameters of IS we had arranged a technical session in our office on dtd. 20.09.2014.

This session was headed by Mr. Arun Kumar (VP) having the vast experience in electrical & mechanical designing of transformer and previously he had served in BHEL, Haridwar as a design Head, Mr. Sandeep Kumar (AGM Design) & Mr. Gaurav Jain (Sr. Manager Marketing) have also attended the technical session to discuss the technical parameters which are defined in revised IS 1180. Our MD Mr. Girish Kumar also attended the technical session and also gives their valuable inputs in technical session.

In this technical session we have discussed the different categories in which transformers have been divided, which are as below.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 200 KVA, 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	16 KVA	4.5%	150W	480W	135W	440W	120W	400W
2	25 KVA	4.5%	210W	695W	190W	635W	175W	595W
3	63 KVA	4.5%	380W	1250W	340W	1140W	300W	1050W
4	100 KVA	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 200 KVA upto and including 2500 KVA, 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	250 KVA	4.5%	1050W	3150W	980W	2930W	920W	2700W
2	315 KVA	4.5%	1100W	3275W	1025W	3100W	955W	2750W
3	400 KVA	4.5%	1300W	3875W	1225W	3450W	1150W	3330 W
4	500 KVA	4.5%	1600W	4750W	1510W	4300W	1430W	4100W
5	630 KVA	4.5%	2000W	5855W	1860W	5300W	1745 W	4850W
6	1000 KVA	5.0%	3000W	9000W	2790W	7700W	2620W	7000W
7	1250 KVA	5.0%	3600W	10750W	3300W	9200W	3220W	8400W
8	1600 KVA	6.25%	4500W	13500W	4200W	11800W	3970W	11300W
9	2000 KVA	6.25%	5400W	17000W	5050W	15000W	4790W	14100W
10	2500 KVA	6.25%	6500W	20000W	6150W	18500W	5900W	17500 W

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

After study of the above we observe followings points which are important for design of transformers:

1) Mr. Sandeep pointed out that losses of energy efficiency level 1 are equivalent to BEE 3 Star Category, energy efficiency level 2 are equivalent to BEE 4 star category and energy efficiency level 3 are equivalent to 5star category for 3 phase distribution transformer upto 200 KVA transformer for 11KV Class.

2) Mr. Gaurav Jain pointed out that losses in energy efficiency level 1 are less than the losses mentioned in ECBC 2009 for transformers higher than 200 KVA upto and including 2500 KVA for 11KV Class

Further to above our design head 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 b) for 3 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 b) for 3 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 5% of the maximum total losses values mentioned in table c) for single phase.

In revised IS 1180 there are also some change in oil & winding temperature rise parameters for each category. It also includes the specification for corrugated type transformers. Since our MD Mr. Girish Kumar & our Organization is always emphasize & committed to saving the energy, so 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.
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