ETX / AET — 33 kV earthing transformers up to 500 kVA, including units combined with auxiliary transformers
Earthing transformers up to 500 kVA at 33 kV that create a neutral in a network without one. The AET version combines neutral earthing and the site auxiliary supply. Used at BESS and renewable energy substations, in 33 kV networks and in industrial distribution networks.
- Rating
- up to 500 kVA
- HV voltage
- 33 kV or on request
- LV voltage (AET)
- 415 or 433 V
- Short-time current
- 1500 A, 10 s
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
Earthing transformers, named after their winding connection, are also called zig-zag transformers. They create a neutral point in a power system where there is none, for example when the power transformer windings are delta-connected, and provide a path to earth for fault currents. During an earth fault, the current flows to earth through such a transformer. This protects equipment, reduces the risk of electric shock to personnel and of fire, and limits transient overvoltages, because the path to earth has low impedance. Rated power is up to 500 kVA.
The manufacturer makes two versions. ETX are 33 kV earthing transformers with a short-time current of up to 1500 A for 10 seconds and vector group ZN or any other per IEC 60076. AET are combined earthing and auxiliary transformers. One unit combines neutral earthing and the supply of site auxiliary loads, including lighting and CCTV. Primary voltage is 33 kV or other on request, secondary 415 or 433 V, short-time current 1500 A / 10 s, groups ZNyn1, ZNyn11 or others per IEC 60076. This combination simplifies installation and saves space.
Earthing transformers are supplied standalone or together with power transformers as part of a complete package for the site. For BESS and solar farms the full set is offered, that is power, MV distribution, auxiliary and earthing transformers. Testing and supply are covered by a 24-month warranty.
As an example of related equipment, at BESS Farnham (20 MW, Tesla Megapack batteries) a 100 kVA 33 kV/433 V auxiliary transformer was installed together with six large 4.2 MVA 33 kV/480 V–480 V distribution transformers. Earthing and auxiliary units are built oil-filled to IEC 60076.
Applications: energy storage and renewable energy substations, 33 kV networks with isolated neutral, industrial distribution networks. Manufacturing is in Leeds (UK) and Chennai (India); the site of more than 5500 m² has three production bays by transformer type and size, two test stands and two paint booths, and the engineering team in the UK adapts designs to project requirements.
Technical specifications
| Rating | up to 500 kVA |
|---|---|
| HV voltage | 33 kV or on request |
| LV voltage (AET) | 415 or 433 V |
| Short-time current | 1500 A, 10 s |
| Vector group | ZN (ETX); ZNyn1 / ZNyn11 (AET) or other per IEC 60076 |
| Design | oil-filled |
| Standards | IEC 60076 |
Replacement for
ФМЗО, ТМПС (neutral-forming ZNyn 6–35 kV); combined with auxiliary transformers (ТСН) — general type
selected by purpose and main parameters, please confirm with our manager
Request a price and lead time
ETX / AET — 33 kV earthing transformers up to 500 kVA, including units combined with auxiliary transformers. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
How do the ETX and AET versions differ?
ETX is a 33 kV earthing transformer with group ZN. AET combines neutral earthing and the supply of site auxiliary loads, with secondary voltage 415 or 433 V.
What short-time current do the earthing transformers withstand?
1500 A for 10 seconds. Rated power is up to 500 kVA.
Which vector groups are available?
ZN for ETX, ZNyn1 or ZNyn11 for AET. Other groups per IEC 60076 are also possible.
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