Choose two-winding when the transformer feeds one network: LV 36–38.5 kV (35 kV class), 6.3–10.5 kV, 21 kV on on-load units, or 13.8–21 kV from 75 MVA. Choose three-winding (YNyn0d11) when one transformer feeds a 35 kV-class network and a lower-voltage network; three-winding units run from 6.3 MVA to 63 MVA.
110 kV Oil-Immersed Power Transformer
For substation contractors and utilities: five 110 kV series, 6.3–180 MVA, three loss levels each, supplied with the substation’s E-Houses.
Power & Utility Grid InfrastructureEnergy Storage & Renewable Infrastructure
Key Metrics
6300–180000kVA
Rated power
110 / 115 / 121kV
High voltage
S22 / S20 / S18
Loss levels
YNd11 / YNyn0d11
Vector group
Product Features
6.3–180 MVA ratings
Sixteen standard ratings from 6.3 MVA to 180 MVA in the two-winding off-circuit series, and eleven from 6.3 MVA to 63 MVA in each of the four other series.
6.3–180 MVA ratings
Sixteen standard ratings from 6.3 MVA to 180 MVA in the two-winding off-circuit series, and eleven from 6.3 MVA to 63 MVA in each of the four other series.
Three loss levels
Every rating comes at S22, S20 or S18; on a 63 MVA two-winding unit, no-load loss is 22.9 kW at S22 against 33.3 kW at S18.
35 kV LV winding
A two-winding series with a 36, 37 or 38.5 kV LV winding connects a 35 kV network to 110 kV through one transformer, from 6.3 MVA to 63 MVA.
Three-winding units
YNyn0d11 units feed a 35 kV-class network and a second, lower-voltage network from one 110 kV transformer, in off-circuit and on-load versions.
On-load regulation
On-load units regulate the HV winding over ±8×1.25%, with 17 positions across ±10%, while the transformer carries load.
Product Details
S stands for three-phase. F appears on units with fan (forced-air) cooling and P on units with forced-directed oil cooling; Z marks on-load tap changing and is left out on off-circuit units. The loss-level code follows, then the rated power in kVA after the hyphen and the voltage class in kV after the slash. SZ20-50000/110 therefore identifies a three-phase on-load unit at loss level S20, rated 50000 kVA at 110 kV.
The two-winding off-circuit series covers 6.3–180 MVA: up to 63 MVA with a 6.3, 6.6 or 10.5 kV LV winding and 10.5% short-circuit impedance, and from 75 MVA with a 13.8–21 kV LV winding and 12–14%. The four other series cover 6.3–63 MVA: two-winding off-circuit with a 36–38.5 kV LV winding, three-winding off-circuit, and two- and three-winding on-load. Two-winding units are YNd11 and three-winding units YNyn0d11. Off-circuit units take an HV rating of 110, 115 or 121 kV, on-load units 110 kV.
Off-circuit units have a ±2×2.5% tap range on the HV winding: five positions, changed with the transformer de-energised, and an HV rating of 110, 115 or 121 kV. On-load units carry a ±8×1.25% on-load tap changer: 17 positions across ±10%, switched while the transformer carries load, with the HV winding rated 110 kV. Their no-load loss is slightly higher than that of the off-circuit unit of the same rating and loss level, for example 25.0 kW against 22.9 kW at 63 MVA and S22.
S22 has the lowest no-load loss; S20 is about 18% higher and S18 about 45% higher. Load loss is the same at S22 and S20 and about 5% higher at S18. In the two-winding off-circuit series, S22 no-load loss runs from 4.1 kW at 6.3 MVA to 49.5 kW at 180 MVA, load loss from 32 kW to 411 kW, and no-load current falls from 0.62% to 0.20%. Values for each series, rating and loss level are confirmed with the quotation.
Three-winding units carry an HV, an MV (36, 37 or 38.5 kV) and an LV winding. Off-circuit units come in a step-up arrangement, with short-circuit impedance HV–MV 17.5–18.5%, HV–LV 10.5% and MV–LV 6.5%, or a step-down arrangement with HV–MV 10.5%, HV–LV 18–19% and MV–LV 6.5%. On-load units use HV–MV 10.5%, HV–LV 17.5–18.5% and MV–LV 6.5%, with an LV winding of 6.3, 6.6, 10.5 or 21 kV.
The core is three-limb or five-limb, the windings are disc type, and the active part is built with formed insulation components. The bell-type tank carries an expansion-type conservator and the transformer’s protective devices. ETENZ confirms the cooling method, protective devices and accessories with the drawings for the selected rating; dimensions and transport mass follow from the same drawings.
Delivery Scope Options
Scope 1
Single Unit or Complete Package Supply
Scope 1Single Unit or Complete Package Supply
Transformers are supplied as single units against the order schedule, or as a complete package together with the protective enclosure, the temperature controller and the cooling fans. The active part is wound, assembled and routine-tested at the works and shipped as a complete unit; the assembly interface for the accessories follows the transport conditions. Where the transformer is to arrive together with a prefabricated power module, the E-House line takes on the enclosure, the internal arrangement and the foundation fixing, and the transformer is delivered as equipment housed within it.
Scope Includes:
Single unit or complete package
Complete-unit shipment and assembly interface
Foundation and fixing interface
In-cabin delivery handled by the E-House line
Technical Specifications
Product form
Three-phase oil-immersed power transformer for 110 kV substation main-transformer service, two- or three-winding
Type designation
S(F)(P)□-□/110 off-circuit; S(F)(P)Z□-□/110 on-load (F fan cooling, P forced-directed oil cooling, Z on-load tap changing; loss-level code-rated power/voltage class)
Rated power, two-winding off-circuit
6300 / 8000 / 10000 / 12500 / 16000 / 20000 / 25000 / 31500 / 40000 / 50000 / 63000 / 75000 / 90000 / 120000 / 150000 / 180000
kVA
Rated power, other four series
6300 / 8000 / 10000 / 12500 / 16000 / 20000 / 25000 / 31500 / 40000 / 50000 / 63000
kVA
HV rating and tap range, off-circuit
110, 115 or 121 kV; ±2×2.5%
HV rating and tap range, on-load
110 kV; ±8×1.25% on-load tap changer
LV, two-winding off-circuit
6.3 / 6.6 / 10.5 (6300–63000 kVA); 13.8 / 15.75 / 18 / 21 (75000–180000 kVA)
kV
LV, two-winding off-circuit with 35 kV LV
36 / 37 / 38.5
kV
LV, two-winding on-load
6.3 / 6.6 / 10.5 / 21
kV
MV and LV, three-winding
MV 36 / 37 / 38.5; LV 6.3 / 6.6 / 10.5 / 21 on-load, agreed for the project off-circuit
kV
Vector group
YNd11 (two-winding); YNyn0d11 (three-winding)
Short-circuit impedance, two-winding
10.5 (6300–63000 kVA); 12–14 (75000–180000 kVA)
%
Short-circuit impedance, three-winding
Off-circuit step-up: HV–MV 17.5–18.5, HV–LV 10.5, MV–LV 6.5; off-circuit step-down: HV–MV 10.5, HV–LV 18–19, MV–LV 6.5; on-load: HV–MV 10.5, HV–LV 17.5–18.5, MV–LV 6.5
%
Loss levels
S22, S20 and S18 for every rating
No-load loss, two-winding off-circuit, S22 / S20 / S18
6300 kVA: 4.1 / 4.8 / 5.9; 63000 kVA: 22.9 / 27.0 / 33.3; 180000 kVA: 49.5 / 58.5 / 72.0
kW
Load loss, two-winding off-circuit, S22 / S20 / S18
6300 kVA: 32 / 32 / 33; 63000 kVA: 187 / 187 / 198; 180000 kVA: 411 / 411 / 434
kW
No-load current, two-winding off-circuit
0.62 (6300 kVA) to 0.20 (180000 kVA)
%
Losses at 63000 kVA, other series, S22 no-load / load
Two-winding with 35 kV LV: 24.0 / 209; three-winding off-circuit: 27.1 / 230; two-winding on-load: 25.0 / 209; three-winding on-load: 29.8 / 230
kW
Construction
Three- or five-limb core; disc windings; formed insulation components; bell-type tank with expansion-type conservator
Cooling
As coded in the type designation: F fan cooling, P forced-directed oil cooling; selected for the rating
Frequency, insulation levels, temperature rise, sound level, dimensions, mass
Confirmed for the selected rating and project
| Parameter | Specification |
|---|---|
| Product form | Three-phase oil-immersed power transformer for 110 kV substation main-transformer service, two- or three-winding |
| Type designation | S(F)(P)□-□/110 off-circuit; S(F)(P)Z□-□/110 on-load (F fan cooling, P forced-directed oil cooling, Z on-load tap changing; loss-level code-rated power/voltage class) |
| Rated power, two-winding off-circuit | 6300 / 8000 / 10000 / 12500 / 16000 / 20000 / 25000 / 31500 / 40000 / 50000 / 63000 / 75000 / 90000 / 120000 / 150000 / 180000 kVA |
| Rated power, other four series | 6300 / 8000 / 10000 / 12500 / 16000 / 20000 / 25000 / 31500 / 40000 / 50000 / 63000 kVA |
| HV rating and tap range, off-circuit | 110, 115 or 121 kV; ±2×2.5% |
| HV rating and tap range, on-load | 110 kV; ±8×1.25% on-load tap changer |
| LV, two-winding off-circuit | 6.3 / 6.6 / 10.5 (6300–63000 kVA); 13.8 / 15.75 / 18 / 21 (75000–180000 kVA) kV |
| LV, two-winding off-circuit with 35 kV LV | 36 / 37 / 38.5 kV |
| LV, two-winding on-load | 6.3 / 6.6 / 10.5 / 21 kV |
| MV and LV, three-winding | MV 36 / 37 / 38.5; LV 6.3 / 6.6 / 10.5 / 21 on-load, agreed for the project off-circuit kV |
| Vector group | YNd11 (two-winding); YNyn0d11 (three-winding) |
| Short-circuit impedance, two-winding | 10.5 (6300–63000 kVA); 12–14 (75000–180000 kVA) % |
| Short-circuit impedance, three-winding | Off-circuit step-up: HV–MV 17.5–18.5, HV–LV 10.5, MV–LV 6.5; off-circuit step-down: HV–MV 10.5, HV–LV 18–19, MV–LV 6.5; on-load: HV–MV 10.5, HV–LV 17.5–18.5, MV–LV 6.5 % |
| Loss levels | S22, S20 and S18 for every rating |
| No-load loss, two-winding off-circuit, S22 / S20 / S18 | 6300 kVA: 4.1 / 4.8 / 5.9; 63000 kVA: 22.9 / 27.0 / 33.3; 180000 kVA: 49.5 / 58.5 / 72.0 kW |
| Load loss, two-winding off-circuit, S22 / S20 / S18 | 6300 kVA: 32 / 32 / 33; 63000 kVA: 187 / 187 / 198; 180000 kVA: 411 / 411 / 434 kW |
| No-load current, two-winding off-circuit | 0.62 (6300 kVA) to 0.20 (180000 kVA) % |
| Losses at 63000 kVA, other series, S22 no-load / load | Two-winding with 35 kV LV: 24.0 / 209; three-winding off-circuit: 27.1 / 230; two-winding on-load: 25.0 / 209; three-winding on-load: 29.8 / 230 kW |
| Construction | Three- or five-limb core; disc windings; formed insulation components; bell-type tank with expansion-type conservator |
| Cooling | As coded in the type designation: F fan cooling, P forced-directed oil cooling; selected for the rating |
| Frequency, insulation levels, temperature rise, sound level, dimensions, mass | Confirmed for the selected rating and project |
Product FAQs
An off-circuit tap changer (±2×2.5%) is set with the transformer de-energised and suits networks where the 110 kV voltage stays steady. An on-load tap changer (±8×1.25%) regulates under load, where the voltage varies in operation. At the same rating, on-load units have slightly higher no-load loss.
Rated power, winding count, tap changer type and loss level set most of the price, followed by the LV voltage, cooling method and accessories. For a quotation, give the rated power, the voltages and vector group, the tap changer type and range, the loss level or loss evaluation figures, the impedance requirement, the site altitude and ambient temperature range, and the document requirements.
Yes. The main transformer stands outdoors on its own foundation, and the ETENZ E-House line supplies the substation buildings as E-Houses, for example the 110kV Secondary Equipment E-House, the Eight-Module GIS Switchgear E-House and the MV Switchgear E-House. Cable and control interfaces between the transformer and the E-Houses are confirmed together at the drawing review.
LV windings come at 6.3, 6.6, 10.5, 21, 36, 37 and 38.5 kV, and at 13.8, 15.75, 18 and 21 kV from 75 MVA. Other LV voltages such as 11 kV or 33 kV, and 60 Hz operation, are confirmed for the project from the voltage ratio, vector group and tap range given with the inquiry.
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