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 1st 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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