Single-phase transformer 400 V / 24 V
24 V AC from two phases · 63 VA to 20 kVA · IP00, IP23 or IP54 · made in France
5.0 · 1 review63 VA2.62 A at 24 V
- —
- —
- 2-year warranty · wound and tested in Gailhan
Key features
This single-phase 400 V to 24 V transformer connects between two phases of a 400 V supply — formerly 380 V — and delivers 24 volts AC: the voltage of control circuits in control panels without a neutral (contactor and relay coils, indicator lamps, solenoid valves), as well as low-voltage lighting and automation. The primary and secondary are two separate windings. From 63 VA to 20 kVA, open frame (IP00), with a ventilated cover (IP23) or in a sealed housing (IP54): it is wound and tested in our workshop in Gailhan, in the Gard (southern France).
The primary connects between two phases of the 400 V supply (L1 and L2, for example): it needs neither a neutral nor a 230 V supply. If your panel has a neutral, the 230 V / 24 V transformer is also suitable.
It supplies 24 V AC (marked 24 V AC or 24 V ~). A PLC, a sensor or electronics running on 24 V DC need a power supply: see AC or DC.
On the primary, both phases go through a two-pole type D circuit breaker or two aM fuses: 2 A for the 63 VA, 4 A for the 1,000 VA. On the secondary, protection rated for the 24 V current: the rating for each size is given in the table.
When should you use a 400 V to 24 V transformer?
- Control circuits in control panels: 24 V AC contactor and relay coils.
- Indicator lamps, illuminated push buttons and industrial panel signalling.
- 24 V AC solenoid valves and motorised valves.
- Automation systems and motor drives supplied from a 400 V supply without a neutral.
- 24 V low-voltage lighting, machine lamps.
- Test benches and machines that need an AC extra-low voltage.
It works on 50 and 60 Hz supplies and delivers AC: for 24 V DC, see the next section.
24 V AC or 24 V DC?
Check the rating plate on your device. The marking tells you which product you need.
- Small 24 V AC motors and automation systems
- 24 V AC solenoid valves and motorised valves
- 24 V AC relay and contactor coils
- Machine lamps and 24 V lighting
- 24 V AC indicator lamps and signalling
- Indicator lights marked 24 V AC
Specifications of the 400 V / 24 V transformer
Values for the selected configuration: 63 VA · IP00.
- Voltage
- 400 V AC, between two phases (formerly 380 V)
- Rated current
- —
- Terminals
- 1 (0 V) · 2 (400 V) · earth
- Recommended protection
- —
- On-load voltage
- 24 V AC
- No-load voltage
- —
- Rated current
- —
- Terminals
- 3 (0 V) · 4 (24 V)
- Recommended protection
- —
- Type
- Dry-type transformer, two separate windings
- Core
- EI laminations, flux density 1.2 T
- Insulation class
- H (180 °C)
- Temperature rise
- 50 °C, 40 °C maximum ambient
- Standards
- EN 61558-2-4 and EN 61558-2-6
- Thermal protection
- On request
- IP rating
- —
- Overall dimensions L × W × H
- —
- Weight
- —
- Mounting
- —
- Altitude
- 3,000 m maximum
- Connection
- Screw terminals up to 55 A (1 kVA on this model), lugs above
From 10 to 20 kVA, losses and efficiency are available on request.
Ratings and prices
From 63 VA to 20 kVA. Above that, or for another voltage, on request.
| Rating | 24 V current | Primary fuse | 24 V protection | No-load / load losses | Efficiency | Weight | Dimensions (mm) | Price ex VAT |
|---|---|---|---|---|---|---|---|---|
| 63 VA | 2.6 A | aM 2 A | aM 4 A | 2 / 3.5 W | 90.5 % | 1.5 kg | 75 × 68 × 73 | €47.42 |
| 100 VA | 4.2 A | aM 2 A | aM 6 A | 3 / 5.2 W | 92.0 % | 2 kg | 84 × 82 × 78 | €57.42 |
| 160 VA | 6.7 A | aM 2 A | aM 8 A | 4 / 8.6 W | 91.9 % | 2.5 kg | 96 × 89 × 87 | €63.25 |
| 200 VA | 8.3 A | aM 2 A | aM 10 A | 5 / 8.9 W | 93.0 % | 2.6 kg | 118 × 97 × 97 | €66.58 |
| 250 VA | 10.4 A | aM 2 A | aM 12 A | 6 / 10.1 W | 93.6 % | 3.9 kg | 108 × 95 × 100 | €78.25 |
| 300 VA | 12.5 A | aM 2 A | aM 16 A | 6 / 14.6 W | 93.0 % | 4 kg | 108 × 103 × 94 | €80.75 |
| 400 VA | 16.7 A | aM 2 A | aM 20 A | 8 / 15 W | 94.2 % | 6 kg | 126 × 122 × 108 | €102.42 |
| 500 VA | 20.8 A | aM 2 A | aM 25 A | 10 / 18.6 W | 94.2 % | 6.8 kg | 126 × 110 × 115 | €112.42 |
| 630 VA | 26.2 A | aM 2 A | aM 32 A | 12 / 22.7 W | 94.4 % | 9 kg | 150 × 124 × 126 | €132.42 |
| 750 VA | 31.2 A | aM 2 A | aM 40 A | 15 / 24.4 W | 94.8 % | 10.3 kg | 150 × 120 × 135 | €144.92 |
| 1 kVA | 41.7 A | aM 4 A | aM 50 A | 18 / 29.2 W | 95.3 % | 14 kg | 150 × 144 × 127 | €175.75 |
| 1.6 kVA | 66.7 A | aM 6 A | aM 80 A | 19 / 46.1 W | 95.9 % | 16.4 kg | 180 × 140 × 160 | €219.92 |
| 2 kVA | 83.3 A | aM 6 A | aM 100 A | 19 / 59.5 W | 96.1 % | 20 kg | 180 × 160 × 160 | €243.25 |
| 2.5 kVA | 104.2 A | aM 8 A | aM 125 A | 24 / 66.7 W | 96.4 % | 24 kg | 180 × 180 × 150 | €250.75 |
| 3 kVA | 125.0 A | aM 8 A | aM 160 A | 37 / 82.2 W | 96.0 % | 29 kg | 180 × 200 × 160 | €288.25 |
| 4 kVA | 166.7 A | aM 12 A | aM 200 A | 42 / 105.2 W | 96.3 % | 33 kg | 240 × 190 × 220 | €425.75 |
| 5 kVA | 208.3 A | aM 16 A | aM 250 A | 45 / 129.7 W | 96.5 % | 36 kg | 240 × 200 × 220 | €458.25 |
| 6.3 kVA | 262.5 A | aM 20 A | aM 315 A | 56 / 132.3 W | 97.0 % | 40 kg | 240 × 210 × 220 | €483.25 |
| 7.5 kVA | 312.5 A | aM 20 A | aM 400 A | 56 / 152.6 W | 97.2 % | 46 kg | 240 × 230 × 220 | €548.25 |
| 10 kVA | 416.7 A | aM 32 A | aM 500 A | —* | —* | 75 kg | 390 × 150 × 470 | €1,012.42 |
| 15 kVA | 625.0 A | aM 40 A | aM 800 A | —* | —* | 80 kg | 390 × 160 × 470 | €1,145.75 |
| 20 kVA | 833.3 A | aM 63 A | aM 1000 A | —* | —* | 95 kg | 390 × 170 × 470 | €1,279.92 |
aM fuses sized for the rated current; alternatively, a type D circuit breaker of the same rating. * 10 to 20 kVA: catalogue weights and dimensions, losses on request.
Cable size on the 24 V side
Voltage drop depends on the current and the length. Aim for less than 5 % (3 % for lighting).
| Cable size | Drop | Voltage at the device | Drop (%) | Verdict |
|---|
Copper cable, resistivity 0.0225 Ω·mm²/m (at operating temperature), outgoing and return conductors, reactance ignored. “Too small for this current”: current-carrying capacity of a PVC-insulated copper cable in conduit, two loaded conductors, for guidance only. Final sizing is the installer's responsibility (IEC 60364; NF C 15-100 in France).
Connection and dimensions
Extracts from the datasheet: diagram, terminal block and dimensions.
PDF · specifications, ratings and part numbers, protection
Primary protection
—
—
24 V protection
—
As close as possible to the transformer, on the 24 V outgoing circuit.
Safety
- Connection with the power off, by a qualified person.
- Earth connected before switching on.
- IP00: inside a closed cabinet or enclosure.
Standards, warranty and options
A standard transformer, made in Gailhan and also available in other voltages.
Frequently asked questions
About the 400 V / 24 V single-phase transformer, connected between two phases.
How do I connect a 400 V to 24 V transformer?
The primary connects between two phases of the 400 V supply, on terminals 1 and 2, with earth to the primary earth terminal; the 24 V circuits are fed from terminals 3 (0 V) and 4 (24 V). The connection diagram is on the datasheet.
Does this 400 V to 24 V transformer need a neutral?
No: it connects between two phases. It is the 400 V to 24 V control transformer for panels that have no neutral. If a neutral is available, a 230 V / 24 V transformer will also do the job.
380 V or 400 V: is it the same transformer?
Yes: 380 V is the former name for the 400 V supply. A 380 V to 24 V transformer and a 400 V to 24 V transformer are the same unit.
Does this 400 V to 24 V transformer supply DC?
No: it supplies 24 V AC. For 24 V DC (PLCs, sensors, electronics), you need a power supply: a regulated 24 V power supply or a rectified 24 V power supply.
Which rating should I choose?
Add up the power of the coils, indicator lamps and equipment supplied at 24 V, multiply by 1.25 and take the next rating up: 100 W of control circuits needs 125 VA, so a 160 VA transformer. The calculator above the table does this for you.
Why do I measure more than 24 V?
Off load, the voltage is slightly higher: about 25.4 V on the 63 VA and 24.7 V on the 1,000 VA. It falls to 24 V when the transformer delivers its rated current. Measure with your multimeter set to AC (V~).
What protection should I install?
On the primary, a two-pole type D circuit breaker or two aM fuses rated for the primary current: 2 A for the 63 VA, 4 A for the 1,000 VA. On the secondary, protection rated for the 24 V current: a 4 A aM fuse for the 63 VA, 50 A for the 1,000 VA. At switch-on, the transformer draws about twelve times its rated current.
What cable size on the 24 V side?
It depends on the current and the length: at 24 V, a 1 V drop is already 4 %. The cable size calculator works it out for your circuit.
IP00, IP23 or IP54: which should I choose?
IP00: open-frame transformer, to be installed in a cabinet or enclosure. IP23: ventilated cover, for a dry room. IP54: moulded housing up to 630 VA, sealed enclosure above that, protected against dust and splashing water. All about IP ratings.
Is it a safety isolating transformer (SELV)?
Yes: 24 V AC is an extra-low voltage, and this transformer complies with the current standards, EN 61558-2-4 and EN 61558-2-6 (safety isolating transformers).
Customer reviews
Reviews posted by customers who bought this transformer (in French).
Site très bien conçu Produit super bien emballé et livraison hyper rapide!!!! Que du bonheur!
Other voltages and alternatives
The same transformer with a 230 V primary, other voltages, and power supplies for 24 V DC. See all our 230 V to 24 V transformers.