Power & Distribution Transformers

High-Efficiency 11/0.415 kV & 33/11 kV Substation Transformer Solutions

Custom-designed 3-phase oil-immersed transformers manufactured strictly with Cold Rolled Grain Oriented (CRGO) silicon steel, delivering ultra-low losses, robust dielectric withstand, and decades of reliable power operation.

Engineering Excellence

World-Class Transformer Engineering & Manufacturing

VOLTCORE Engineering Solutions manufactures robust 3-Phase Distribution and Power Transformers custom-engineered to client requirements and international standards including IEC, ANSI, BS, VDE, and BSTI.

Our transformers range in rating from 50 KVA to 5,000 KVA for 11/0.415 kV distribution networks and up to 18,000 KVA for 33/11 kV grid substations. As a consistent guarantee of the highest quality, our transformers are fabricated with high-permeability Cold Rolled Grain Oriented (CRGO) silicon steel laminations with step-lap mitered joints for minimal hysteresis and eddy-current core loss.

Our engineering team is closely affiliated with international professional bodies such as IEEE and ASME, continuously incorporating state-of-the-art power engineering developments. Quality control is executed at every single stage of production, and all units undergo exhaustive routine and type testing in our well-equipped high-voltage testing laboratory in compliance with IEC-76, BDS-1081, ANSI, and BSTI standards.

Global Engineering Affiliations & Research Compliance:

IEEE (Institute of Electrical and Electronics Engineers) ASME (American Society of Mechanical Engineers) BSTI / BDS-1081 Certified IEC 60076 Conformance

Voltcore Official Quality Policy & Assurance Pillars

Reliable Power

The Reliable Power: High dielectric stability, heavy-duty thermal endurance, and vacuum-treated mineral transformer oil.

Customer Priority

Customer-Centric Engineering: Fully tailored impedance, tapping ranges, dual LV/HV bushings, and custom enclosure dimensions.

In-Time Delivery

24/7 In-Time Delivery & Support: Emergency breakdown dispatch, testing, commissioning, and preventive maintenance contracts.

Continuous CRGO Lab Testing

Continuous CRGO Optimization: Precision step-lap core stacking, low contact erosion, and low-loss electrolytic copper windings.

Substation Voltage Classes

Engineered Transformer Solutions: 11kV & 33kV

Whether stepping down 11kV utility feeds to 415V for industrial and commercial factories, or stepping down 33kV primary transmission lines to 11kV for utility substations, Voltcore delivers turnkey custom-engineered transformers.

Distribution Class

11 / 0.415 kV

11 / 0.415 kV 3-Phase Distribution Transformers

Primary 11,000V (11kV) • Secondary 415V / 440V

Capacity Range: Standard Ratings: 50 KVA up to 3,000 KVA (and up to 5,000 KVA on request)

Engineered for commercial complexes, industrial plants, RMG factories, residential developments, and rural electrification networks. Built with corrugated cooling fins or pressed sheet radiators for superior natural oil circulation (ONAN).

Standard Design Features:

Off-Circuit Tap Switch: ±2.5%, ±5% or ±2×2.5% to -7.5%
Core: High-grade CRGO M4 / M5 prime silicon steel
Windings: 99.9% electrolytic high-conductivity copper
Tank: Hermetically sealed or conservator tank with silica gel breather
Bushings: High-voltage porcelain DIN bushings with arc horns
Protection: Oil level indicator, thermometer pocket, pressure relief device

Power Class

33 / 11 kV

33 / 11 kV 3-Phase Power Transformers

Primary 33,000V (33kV) • Secondary 11,000V (11kV)

Capacity Range: Standard Ratings: 1,000 KVA up to 18,000 KVA (18 MVA)

Heavy-duty substation power transformers engineered for utility grid step-down, industrial economic zones (EPZ), high-demand manufacturing plants, and utility-scale solar power grid interconnects. Designed to withstand severe lightning impulses, switching over-voltages, and system short-circuit stresses.

Standard Design Features:

Tappings: Off-Circuit Tap Changer (OCTC) or On-Load Tap Changer (OLTC)
Cooling: ONAN (Oil Natural Air Natural) / ONAF (Oil Natural Air Forced)
Core: Step-lap CRGO with high stacking factor and low magnetizing current
Protection: Buchholz double-float gas relay, magnetic oil gauge (MOG), WTI & OTI with alarm/trip contacts
Impulse Withstand: Up to 170 kV BIL peak impulse insulation level
Testing: Rigorous routine, temperature rise, and impulse testing according to IEC 60076

Engineering Standards

Transformer Design Parameters & Construction Standards

Applicable Standards

IEC 76, BDS-1081, ANSI, VDE, BS, AEC, BSTI

System Frequency

50 Hz standard (60 Hz available on request)

Ratings Capacity

50 KVA to 5,000 KVA (Distribution) | 1,000 KVA to 18,000 KVA (33/11kV Power)

Primary Voltages

11 kV or 33 kV (Values above 24 kV up to 36 kV; Double high voltages 15–20 kV available)

Tapping Facilities

2.5%; ±5% or ±2×2.5% to -7.5% (Off-Circuit or On-Load Tap Changer)

Secondary Voltages

415V to 440V (Double low voltages with 7 LV bushings with full rating on both voltages or 75% on load)

Core Magnetic Material

Prime Cold Rolled Grain Oriented (CRGO) silicon steel laminations

Cooling Medium

ONAN (Oil Natural Air Natural) / ONAF (Oil Natural Air Forced)

Insulation Class & Vector Group

Class A (105°C) uniform insulation with premium Kraft paper and pressboard spacers • Dyn11 (Standard 11kV Distribution) | YNd11 or Dyn11 (33kV Power)

Official Brochure Extraction

Electrical Specifications for Transformers

Full technical data table covering losses, efficiency at unity power factor, oil weight, total weight, overall dimensions, and impedance voltage.

Table 1: 11000/415 Volt, 3-Phase Distribution Transformers 17 Standard Ratings

System Frequency: 50Hz • Cooling: ONAN • Core: CRGO Silicon Steel

Sl.	Capacity (kVA)	No Load Loss (W)	Load Loss at 75°C (W)	Efficiency @ Unity PF (%)	Oil Wt (kg)	Total Wt (kg)	Length (cm)	Width (cm)	Height (cm)	Impedance (%)
01	50 KVA	150	925	98.00%	140	580	94	58	118	4.0%
02	100 KVA	245	1700	98.42%	180	650	100	63	132	4.0%
03	150 KVA	320	2412	98.60%	220	900	105	88	145	4.0%
04	200 KVA	435	2820	98.79%	230	975	112	93	150	4.0%
05	250 KVA	520	3265	98.81%	270	1100	113	95	158	4.0%
06	315 KVA	580	4500	98.89%	350	1250	120	97	160	4.0%
07	400 KVA	722	5490	98.95%	390	1450	123	98	162	4.0%
08	500 KVA	865	6275	99.00%	425	1725	124	102	165	4.0%
09	630 KVA	920	7740	99.05%	500	1970	136	103	170	4.5%
10	750 KVA	1150	8850	99.06%	625	2250	155	112	185	5.0%
11	800 KVA	1300	9800	99.06%	650	2575	170	113	200	5.0%
12	1000 KVA	1650	11600	99.08%	800	2850	185	115	215	5.0%
13	1250 KVA	1820	12300	99.10%	1000	3725	190	116	225	5.0%
14	1600 KVA	2200	14275	99.12%	1200	4300	200	120	230	6.0%
15	2000 KVA	2650	16470	99.15%	1450	4750	210	135	250	6.0%
16	2500 KVA	3140	19700	99.17%	1800	5600	220	150	285	6.5%
17	3000 KVA	3420	22860	99.19%	2050	6350	230	170	300	6.5%

Sl.	Capacity (kVA)	No Load Loss (W)	Load Loss at 75°C (W)	Efficiency @ Unity PF (%)	Oil Wt (kg)	Total Wt (kg)	Length (cm)	Width (cm)	Height (cm)	Impedance (%)
01	1000 KVA	1750	12500	98.95%	850	4000	195	165	220	6–7%
02	1250 KVA	2050	14900	98.97%	1000	4800	200	170	225	6–7%
03	1500 KVA	2380	16900	98.98%	1170	5400	205	175	228	6–7%
04	1600 KVA	2470	17800	98.98%	1260	5700	209	180	230	6–7%
05	2000 KVA	2950	21000	99.00%	1450	6600	215	188	237	6–7%
06	2200 KVA	3150	22500	99.01%	1600	7300	220	195	242	6–7%
07	2500 KVA	3500	24700	99.02%	1750	8050	230	205	250	6–7%
08	2800 KVA	3800	26800	99.02%	1900	8600	235	210	256	6–7%
09	3000 KVA	4000	27900	99.03%	2000	9200	242	220	262	6–7%
10	3500 KVA	4500	30700	99.03%	2250	10250	250	229	268	6–7%
11	3800 KVA	4750	32200	99.02%	2450	10900	258	235	273	6–7%
12	4000 KVA	5000	33500	99.03%	2500	11000	264	244	277	6–7%
13	4400 KVA	5300	35000	99.04%	2650	11850	270	250	285	6–7%
14	4800 KVA	5650	37000	99.04%	2850	12500	276	260	290	6–7%
15	5000 KVA	5850	37500	99.05%	2950	12800	285	268	297	6–7%
16	5500 KVA	6250	39700	99.03%	3170	13600	293	275	300	6–8%
17	6000 KVA	6700	41800	99.04%	3400	14400	300	285	310	6–8%
18	6500 KVA	7100	43700	99.04%	3600	15200	305	291	315	6–8%
19	7000 KVA	7500	45600	99.05%	3800	15900	312	300	320	6–8%
20	8000 KVA	8300	50000	99.05%	4220	17500	320	308	327	6–8%
21	8500 KVA	8700	51200	99.05%	4400	18000	327	317	332	6–8%
22	9000 KVA	9200	52800	99.06%	4600	18700	335	325	340	6–8%
23	9500 KVA	9400	55000	99.08%	4800	19400	340	330	345	6–8%
24	10000 KVA	9800	56000	99.08%	4900	19900	348	340	350	6–8%
25	10000 KVA	9800	56000	99.10%	4900	19900	348	340	350	6–8%
26	11000 KVA	10600	60000	99.11%	5300	21200	350	345	355	7–10%
27	12000 KVA	11300	64000	99.12%	5600	22500	355	347	359	7–10%
28	13000 KVA	12200	68000	99.14%	6000	23800	360	351	362	7–10%
29	14000 KVA	12800	71700	99.15%	6300	25000	363	355	366	7–10%
30	15000 KVA	13600	75400	99.18%	6600	26200	367	360	370	7–10%
31	16000 KVA	14300	79300	99.19%	7000	27400	370	363	374	7–10%
32	17000 KVA	15000	82900	99.19%	7300	28500	375	367	380	7–10%
33	18000 KVA	15700	86500	99.20%	7600	29600	380	372	382	7–10%

* Note on Specifications: All transformer specifications, loss levels, weights, and overall dimensions conform to official IEC-76 and BDS-1081 standards. Custom impedance voltages, special primary/secondary voltage combinations, and customized dimensional footprints can be engineered strictly as per customer requirements upon technical review.

Turnkey Substation EPC

Complete 33/11kV & 11/0.415kV Substation System Integration

In addition to manufacturing world-class transformers, VOLTCORE provides complete HT Switchgear (VCB/LBS), LT Switchgear, Power Factor Improvement (PFI) Plants, Lightning Protection, and Substation Earthing systems.

Explore Substation EPC Services → View HT/LT Switchgear →