400 kVA power class
400 kVA Diesel Generator (320 kW)
A 400 kVA diesel generator produces 320 kW at a 0.8 power factor. It sits at the point where a single machine can carry a full commercial building services load or a technical facility, and where containerised builds and paralleling controls start to be normal rather than unusual.
Ratings
Ratings at a glance
| Parameter | Value |
|---|---|
| Prime power (PRP) | 400 kVA / 320 kW |
| Emergency standby (ESP) | 440 kVA / 352 kW |
| Rated voltage and frequency | 400/230 V, 50 Hz (380/220 V or 60 Hz on request) |
| Rated speed | 1500 rpm, four-pole (1800 rpm for 60 Hz) |
| Full-load current | 577 A per phase at 400 V |
| Typical duty | Standby for a complete building or process line; prime power for industrial and rental duty |
Specification envelope
What is normally inside a 400 kVA set
| Item | Typical range | Why it matters |
|---|---|---|
| Engine | Six-cylinder, 11.0-13.0 L, electronic governor | Block load acceptance and fuel map across the load range |
| Alternator | Brushless, class H insulation, IP23, AVR controlled, 2/3 pitch | Voltage recovery after large load steps, harmonics with drives |
| Fuel consumption | 58-65 L/h at 75% load (240 kW) | Tank sizing for day tanks and bulk storage |
| Base tank autonomy | 500-650 L, 8-10 h at 75% load | Autonomy without a bulk tank installation |
| Noise at 7 m | 68-75 dB(A) canopy, 80-86 dB(A) open frame | Noise limits near residential or hotel boundaries |
| Weight | 3.3-4.2 t open, 3.5-4.5 t canopy | Foundation design and lifting equipment |
| Footprint | Approximately 4.2-4.8 m x 1.5 m canopy | Plant room height, door widths and service clearances |
Sizing
Getting a 400 kVA specification right
- Write the load schedule first. Connected kW, running kW, power factor and starting method for each item. The schedule, not the total, decides the rating.
- Check the largest step. Lift motors, chiller compressors and pump sets determine the permitted step load. Where the step exceeds the engine capability, staging or soft starting is the cheap answer; a larger set is the reliable one.
- Plan the fuel installation. Above 500 L, most jurisdictions treat the tank as a regulated installation: bunding, venting, fire separation and often a day tank in the plant room.
- Decide single or parallel. Two 400 kVA sets give N+1 redundancy for a critical bus; a single set gives the lowest first cost. The decision changes the switchgear, the control panels and the cabling.
Applications
Typical 400 kVA applications
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Hospitals and medical buildings
Whole-facility standby where the essential bus covers theatres, imaging equipment, medical gas and cold rooms.
-
Production lines and plants
Process lines and utilities, with the set sized around the largest motor and the plant restart sequence.
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Data and IT facilities
Small data halls and server rooms, normally as one of two sets so that either can carry the technical load.
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District cooling and pumping
Chiller and pump stations where the electrical load is dominated by large drives starting in sequence.
Options
Options usually specified at 400 kVA
| Option | What it changes |
|---|---|
| Containerised build | Weather protection, security and a walk-in service space around the set, with the tank and cabling inside |
| Paralleling panel | Load sharing, synchronising and protection so that two sets can run together or as N+1 |
| Critical silencer | Lower night-time noise at the boundary, usually at the cost of exhaust back pressure and space |
| Motorised breaker with AMF | Automatic start, transfer and return, with adjustable transfer and cool-down delays |
| Remote monitoring | Fuel level, run hours, alarms and mains status reported to an operator or to a service desk |
Questions
400 kVA questions we are asked
How many kW is a 400 kVA generator?
320 kW at 0.8 power factor, or 352 kW at the emergency standby rating of 440 kVA. Both figures describe the same machine, and the rating has to be stated whenever a number is quoted in a tender.
How much fuel does a 400 kVA generator use per hour?
Budget 58-65 L/h at 75% load, which is 240 kW, and roughly 77-87 L/h at full load. A 24 hour run at 75% load therefore consumes about 1.4 to 1.6 cubic metres of fuel, which is why installations above this rating usually include a bulk tank.
How many amps is a 400 kVA generator?
577 A per phase at 400 V, rising to about 635 A at the standby rating. Busbar, cabling and switchgear are normally selected for the standby current so that the higher rating can be used without a rework.
Should I buy one 400 kVA set or two 200 kVA sets?
If the load can be split and is not critical, two smaller sets are cheaper to buy and easier to move. If the load is a single critical bus, one 400 kVA set costs less than two sets plus a paralleling panel, but it leaves no redundancy; two 400 kVA sets are the usual answer for a technical facility.
Does a 400 kVA generator need a concrete foundation?
It needs a level, load-bearing base. A canopy set is normally bolted to a concrete plinth with anti-vibration mounts, and the plinth is sized for the static weight of roughly 3.5 to 4.5 t plus the fuel. Containerised sets need a flat slab with drainage and clear access for panel doors.
Related
Other pages in this range
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Diesel generator sets
Ratings, form factors and how a specification is assembled.
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300 kVA
240 kW, for essential boards and cold store loads.
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500 kVA
400 kW, the usual step up for hospitals and small data halls.
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Request a quote
Send the load list and site conditions, and we reply with the rating and build options.
Specifying a 400 kVA machine?
Send the load schedule, the largest load step and the fuel autonomy you need. You will get a rating, a fuel figure and the enclosure and control options that fit.