Three-phase isolation transformer 400 V / 400 V + N
Isolates and creates the neutral · vector group Dyn11 · 1 to 100 kVA · made in France
5.0 · 5 reviews10 kVA14.4 A per phase on the secondary
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- 5-year warranty · wound and tested in Gailhan
Key features
This three-phase isolation transformer galvanically separates your installation from the 3 × 400 V supply and gives it a neutral: on the secondary, 400 V between phases and 230 V between each phase and neutral. Vector group Dyn11, electrostatic shield as standard, 1 to 100 kVA in IP00, IP23 or IP54, and 125 to 1,000 kVA on request: it is wound and tested in our workshop in Gailhan, in the Gard (southern France). Standard EN IEC 61558-2-4 calls it an isolating transformer.
This is the most common use of this isolation transformer: the three phases and earth come in on the primary, and the neutral is brought out at secondary terminal 2N. You then have 230 V between each phase and this neutral, for your socket outlets and single-phase equipment.
Variable speed drives and phase converters leak small currents to earth, and these add up. Isolated by this transformer, the machine forms a separate circuit: its leakage no longer reaches the upstream RCD. On the secondary, connect the neutral to earth and protect the secondary with its own RCD.
400 V between phases at the output, as at the input: it isolates and creates the neutral. To step down to 3 × 230 V, choose the 400 V / 230 V + N transformer; for a single 230 V output, the three-phase to single-phase transformer.
When should you use a three-phase isolation transformer?
- Creating a neutral on a 3 × 400 V supply that has none, to power 230 V equipment.
- Isolating a machine whose leakage currents trip the upstream RCD: variable speed drive, phase converter.
- Changing from an IT to a TN-S earthing system, or creating an IT island monitored by an insulation monitoring device.
- Reducing the transmission of supply disturbances to a sensitive installation, thanks to the earthed shield.
It works at 50 Hz, or at 60 Hz on confirmation. It is not suitable for 400 Hz supplies.
Specifications of the three-phase isolation transformer 400 V / 400 V + N
Values for the selected configuration: 10 kVA · IP23.
- Phase-to-phase voltage
- 3 × 400 V
- Connection
- Delta (Δ)
- Rated line current
- 14.4 A
- Terminals
- 1U 1V 1W + PE
- Phase-to-phase voltage
- 3 × 400 V
- Connection
- Star with neutral (YN)
- Rated line current
- 14.4 A
- Phase-to-neutral voltage
- 230 V
- Terminals
- 2U 2V 2W 2N + PE
- Type
- Dry-type transformer, natural cooling
- Core
- 3 limbs, one coil per phase
- Insulation class
- H (180 °C)
- Electrostatic shield
- Fitted as standard, earthed
- Standards
- EN IEC 61558-1 and EN IEC 61558-2-4
- IP rating
- IP23, ventilated metal enclosure
- Overall dimensions L × W × H
- 525 × 320 × 550 mm
- Weight
- 131 kg
- Mounting
- 2 feet, holes Ø 12 mm
- Ambient temperature
- 40 °C maximum
From 63 to 100 kVA, losses and efficiency are available on request.
Ratings and prices
From 1 to 100 kVA. Above that, on request.
| Rating | Current | Recommended circuit breaker | No-load / load losses | Efficiency | Weight | Dimensions (mm) | Price ex VAT | Dispatch |
|---|---|---|---|---|---|---|---|---|
| 1 kVA | 1.4 A | D 2 A | 13 / 54 W | 93.8 % | 13 kg | 340 × 310 × 350 | €381.58 | 3 days |
| 2 kVA | 2.9 A | D 4 A | 22 / 106 W | 94.0 % | 20 kg | 340 × 310 × 350 | €430.75 | 3 days |
| 2.5 kVA | 3.6 A | D 4 A | 24 / 125 W | 94.4 % | 22 kg | 340 × 310 × 350 | €448.25 | 3 days |
| 3.15 kVA | 4.5 A | D 6 A | 30 / 138 W | 94.9 % | 26 kg | 340 × 310 × 350 | €467.42 | 3 days |
| 4 kVA | 5.8 A | D 10 A | 42 / 236 W | 93.5 % | 40 kg | 460 × 320 × 500 | €665.75 | 3 days |
| 5 kVA | 7.2 A | D 10 A | 51 / 258 W | 94.2 % | 46 kg | 460 × 320 × 500 | €694.92 | 3 days |
| 6.3 kVA | 9.1 A | D 10 A | 55 / 309 W | 94.5 % | 50 kg | 460 × 320 × 500 | €736.58 | 3 days |
| 8 kVA | 11.5 A | D 16 A | 90 / 273 W | 95.7 % | 75 kg | 525 × 335 × 550 | €1,031.58 | 3 days |
| 10 kVA | 14.4 A | D 16 A | 98 / 322 W | 96.0 % | 81 kg | 525 × 335 × 550 | €1,094.92 | 3 days |
| 12 kVA | 17.3 A | D 20 A | 114 / 363 W | 96.2 % | 92 kg | 525 × 335 × 550 | €1,425.75 | 3 days |
| 16 kVA | 23.1 A | D 25 A | 131 / 413 W | 96.7 % | 105 kg | 525 × 335 × 550 | €1,432.42 | 3 days |
| 20 kVA | 28.9 A | D 32 A | 147 / 503 W | 96.9 % | 116 kg | 525 × 335 × 550 | €1,514.92 | 3 days |
| 25 kVA | 36.1 A | D 40 A | 163 / 535 W | 97.3 % | 131 kg | 525 × 335 × 550 | €1,686.58 | 3 days |
| 30 kVA | 43.3 A | D 50 A | 171 / 703 W | 97.2 % | 137 kg | 525 × 335 × 550 | €1,854.08 | 3 days |
| 40 kVA | 57.7 A | D 63 A | 158 / 856 W | 97.5 % | 138 kg | 700 × 480 × 720 | €2,255.75 | 3 days |
| 50 kVA | 72.2 A | D 80 A | 206 / 883 W | 97.9 % | 173 kg | 700 × 480 × 720 | €2,383.25 | 3 days |
| 63 kVA | 90.9 A | D 100 A | —* | —* | 220 kg | 700 × 480 × 720 | €3,789.92 | 6 days |
| 80 kVA | 115.5 A | D 125 A | —* | —* | 300 kg | 700 × 480 × 720 | €4,591.58 | 6 days |
| 100 kVA | 144.3 A | MCCB 160 A | —* | —* | 345 kg | 700 × 480 × 720 | €5,358.25 | 6 days |
| 125 to 1,000 kVA | On request, in the standard ratings: 125, 160, 200, 250, 315, 400, 500, 630, 800 and 1,000 kVA. Request a quote | |||||||
Rated current primary = secondary (1:1 ratio). Type D circuit breaker on the primary. Losses and efficiency: design values at full load. * 63 to 100 kVA: losses and efficiency on request. Prices exclude carriage. Calculator formula: kVA = √3 × 400 V × A ÷ 1,000 (current on the 400 V side), next standard rating up.
Wiring diagram and enclosure drawing
Extracts from the datasheet: coil-by-coil connections and enclosure dimensions.
Installation and protection
Values for 25 kVA. Sizing of the installation remains the installer's responsibility.
Upstream protection
Type D circuit breaker 40 A
or aM fuses 40 A · inrush current ≈ 433 A peak
Secondary neutral
- Earthed: TN-S system, the most common.
- Isolated from earth: IT system, with an insulation monitoring device.
Safety
- Connection by a qualified person.
- Earth connected before switching on.
- IP00: in a cabinet or a closed electrical room.
Standards, warranty and options
A standard transformer, built to order and adaptable to your installation.
Frequently asked questions
About the three-phase isolation transformer 400 V / 400 V + N.
What is a 400 V / 400 V three-phase isolation transformer used for?
To galvanically separate an installation from the supply feeding it, without changing the voltage. Its star-connected secondary also provides a neutral: on a 3 × 400 V supply without neutral, you get 230 V between each phase and this neutral.
How do you create a neutral on a three-phase supply without one?
Connect the three phases and earth to the primary (1U, 1V, 1W, PE): the neutral is available at secondary terminal 2N, with 230 V between each phase and this neutral.
How do you wire a three-phase isolation transformer?
Primary connection: the supply goes to terminals 1U, 1V and 1W, earth to PE; the delta connection is made at the factory. On the secondary, the outgoing circuits leave from terminals 2U, 2V and 2W, and the neutral from terminal 2N. The full wiring diagram is on the datasheet.
Should the secondary neutral be connected to earth?
Earthed at the transformer, it gives you a TN-S system, the most common. Isolated from earth, it is an IT system, which requires an insulation monitoring device. The choice is the installer's.
Isolation transformer or isolating transformer: what is the difference?
None: standard EN IEC 61558-2-4 calls it an “isolating transformer”. Both names refer to a transformer whose secondary has no electrical connection with the primary.
Which rating should I choose?
To choose your three-phase isolation transformer, multiply the current per phase on the 400 V side by 400 V and by √3, then take the next standard rating up. For 32 A per phase: 22.2 kVA, so a 25 kVA unit. The calculator above the table does this for you.
Do you make three-phase transformers above 100 kVA?
Yes, on request: we also make this three-phase isolation transformer from 125 to 1,000 kVA, in the standard ratings 125, 160, 200, 250, 315, 400, 500, 630, 800 and 1,000 kVA. Choose the rating at the top of the page, below the priced ratings, or request a quote: reply within 48 h.
What upstream protection should I install?
On the primary (400 V) of your isolation transformer, a type D circuit breaker or aM fuses sized for the rated current: for 25 kVA, 36.1 A per phase, i.e. a 40 A type D circuit breaker or 40 A aM fuses. At switch-on, the inrush current reaches about twelve times the rated current; the rating for each size is given in the table.
IP00, IP23 or IP54: which should I choose?
IP00: open-frame transformer, to be installed in a cabinet or a closed electrical room. IP23: ventilated enclosure, for a plant room sheltered from water. IP54: closed enclosure, protected against dust and splashing water.
What are the lead times?
From 1 to 50 kVA, dispatched from our workshop within 3 working days; from 63 to 100 kVA, within 6 working days. Up to 30 kg, the transformer ships as a parcel, with free delivery within France. Heavier units travel on a pallet with Kuehne + Nagel: 48 to 72 hours in mainland France, 96 hours elsewhere in Europe; pallet delivery is free from €1,000 ex VAT, otherwise a flat €50 ex VAT.
Customer reviews
Reviews posted by customers who bought this transformer (in French).
Note sans commentaire.
Livraison rapide, produit conforme et bien emballé. Installation sans difficulté, parfait pour créer un neutre. Le service téléphonique est top, fabrication française en plus. Je recommande sans hésiter.
Produit reçu rapidement, très bien emballé. Fonctionne parfaitement sur notre installation industrielle. Fabrication sérieuse, rien à signaler après plusieurs semaines d'utilisation. Content d'acheter français.
Produit conforme à la description, fabrication robuste et délai respecté. Service client à l’écoute, installation réalisée sans souci. Très satisfait de la qualité, matériel professionnel, rien à dire de plus.
J'ai commandé ce transformateur d'isolation en 10kVa pour alimenter une machine triphasée avec un convertisseur de phase. Sans transformateur d'isolation, le différentiel 500mA sautait dès la mise sous tension (probablement bruit HF induisant des fuites à la terre par les capa de filtrage), avec le transformateur d'isolation (mais la terre bien branchée partout !) plus aucun problème, même le différentiel 30mA ne bouge pas. Donc plus que satisfait. A savoir, une fois le couvercle enlevé, il y a des anneaux de levage pour manutentionner le transformateur (parce que ça pèse son poids, quand même ;) ).
Other three-phase transformers
Built the same way, for other voltages. See all our three-phase transformers.