In short. A 25 kVA generator delivers 20 kW at 0.8 power factor and 34.8 A per phase at 415 V three-phase. In Hyderabad it is the usual size for a small fabrication or machining workshop, a commercial floor of 40 to 60 seats, or a restaurant that must keep its kitchen exhaust, cold storage and a few air-conditioners running. Reddy Generators supplies new 25 kVA sets through supply tie-ups with all major makes, all CPCB IV+ compliant in acoustic canopies, rents sets, sells used and refurbished 25 kVA sets, and services every make; the price is given on request. Below: what 25 kVA will and will not carry, its diesel use, auto-start, and what it needs on site.
Who this page is for: Owners of small fabrication and machining workshops, restaurants and commercial floors in Hyderabad and Secunderabad who are pricing a 25 kVA set, want to know whether it will carry their machines, welding and air-conditioning, and need to decide between buying new, buying used or renting.
Key facts
- Output: 25 kVA = 20 kW at 0.8 power factor.
- Full-load current, three-phase 415 V: 25 × 1.391 = 34.8 A per phase. Each phase can carry about 8.3 kVA (about 6.7 kW).
- Single-phase 230 V version: 25 × 4.348 = 108.7 A. It exists from some makes but is uncommon at this size; three-phase is the normal build.
- Diesel use (approximate): about 3.0–3.3 L/h at 50 % load (10 kW) and 4.4–4.8 L/h at 75 % load (15 kW), on a basis of roughly 0.29–0.33 L per kWh. The make’s data sheet decides.
- Noise: new sets are supplied in CPCB IV+ acoustic canopies, limited to 75 dB(A) at 1 m.
- Protection and cable (typical): 40 A four-pole breaker; 10 sq mm copper or 16 sq mm aluminium four-core armoured cable for runs of a few tens of metres. Confirm with the breaker, changeover and cable size chart.
- Largest motor, direct-on-line (rule of thumb): about 5 HP with other load running; 7.5 HP only if started first on a lightly loaded set.
- Typical uses: workshops, restaurants, office floors, showrooms, larger villas.
Get price
Generator prices change every day, so we do not print them on the website. Tell us whether you want to buy new, buy used or rent a 25 kVA set, single or three phase, and where the site is. We will send the price.
- New set: the price excludes GST, transport and installation.
- Rental: the rate covers the generator only. Transport is charged at actuals and is in the customer’s scope. Cable and an operator are extra charges if you need them.
- Used or refurbished: priced set by set on make, running hours and condition. Every set is load-bank tested before sale; refurbished sets carry a six-month warranty (rubber and plastic parts, consumables, fuel damage and overload excluded); used sets sold as-is come with an inspection report.
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What a 25 kVA generator can run
At 25 kVA a generator stops being only for lights and computers and starts carrying machines: enough engine for an air compressor, a few machine tools and the office, but not enough margin to forgive careless starting or a heavy welder. The deciding figure is usually the hardest start: the brief surge in kVA the set must ride through without tripping contactors or UPS units.
| Premises and load set (illustrative) | Running load, approx. | Hardest start and allowance | Fits 25 kVA? |
|---|---|---|---|
| Fabrication shop: lighting, 5 HP air compressor, two 1 HP drills, one 200 A three-phase inverter welder, hand grinders | 15–16 kW | Compressor on DOL, about 35 kVA for a second | Yes, with the operating rules in the worked example below |
| Machining unit: lathe 3 HP, milling 3 HP, drill 1 HP, compressor 3 HP, lighting and office | 10–12 kW | 3 HP DOL motor, about 21 kVA | Yes, comfortably |
| Restaurant, 60–80 covers: 3 HP kitchen exhaust, 2 HP fresh-air fan, 2 HP cold room, freezers, lighting, three ACs | 13–15 kW | Cold-room compressor or exhaust motor, 14–21 kVA | Yes; stagger the ACs after changeover |
| Commercial floor, 40–60 seats: lighting, 10 kVA UPS, four inverter ACs, pantry | 14–16 kW | Low; ACs restarting together | Yes |
| Villa: five ACs, 3 HP borewell, kitchen, lighting | 10–12 kW | Borewell DOL, about 21 kVA | Yes |
| Shop with a transformer-type arc welder, or a 400 A welder | Pulsed, uneven per phase | Very high, repeated | No; see the welding caution |
| Fabrication shop plus a second 5 HP compressor and a 7.5 HP DOL machine | 20 kW and above | Two large starts | No; consider 30 kVA or soft starting |
The general method is in the 15–50 kVA guide. Specific to 25 kVA: the comfortable working limit is about 16 kW, not 20 kW, keeping around 20 % in hand for summer afternoons and motor starts.
How many ACs can a 25 kVA generator run?
ACs are single-phase, so one phase sets the answer. Each phase carries about 6.7 kW; leave about 1.7 kW for lighting and computers and roughly 5 kW remains. A fixed-speed 1.5-ton split draws 1.6–1.9 kW in a Hyderabad summer, an inverter unit about 1.2–1.5 kW at full output. That gives about 7 to 8 fixed-speed or about 9 to 10 inverter units in total. The catch is starting: a fixed-speed compressor restarting against pressure takes three to five times its running current, and after changeover every AC restarts at once. Three on one phase can sag the voltage enough to trip the set. Use restart delays or timers so they return 30 to 60 seconds apart; inverter units ramp up gently.
The largest motor a 25 kVA set can start
A direct-on-line (DOL) motor draws six to seven times full-load current while accelerating. Screening rule: a set dips about 10 % on a start equal to its rating and 20–30 % at two to three times. A 5 HP motor (3.7 kW, efficiency 0.85, power factor 0.82) runs at about 5.3 kVA and starts at about 35 kVA, 1.4 times 25 kVA: a dip near 15 %, acceptable. A 7.5 HP motor starts at about 49 kVA, nearly twice the rating, so only on a lightly loaded set. Star-delta cuts starting kVA to about a third, making 10 HP workable.
Welding on a 25 kVA generator: a caution
Welding is the commonest reason a 25 kVA set disappoints in a fabrication shop. An arc load jumps every time it is struck, so governor and voltage regulator chase it constantly.
- Three-phase inverter welders load all phases and recover quickly. Rule of thumb: keep the welder’s rated input below about 35–40 % of the set, so one machine of roughly 200–250 A, and do not weld while the compressor starts.
- Transformer-type arc welders usually connect across two phases at 415 V, loading two phases heavily and leaving the third light, well beyond the alternator’s imbalance limit. Do not run them on a 25 kVA set.
Diesel consumption per hour
Sets of this size use roughly 0.28–0.33 litres per kWh between half and full load, and more at light load because friction and cooling losses do not fall with load. Figures are approximate; the data sheet of the make you buy decides.
| Load | Output | Basis, L per kWh (approx.) | Diesel use, L/h (approx.) |
|---|---|---|---|
| 25 % | 5 kW | 0.36–0.42 | 1.8–2.1 |
| 50 % | 10 kW | 0.30–0.33 | 3.0–3.3 |
| 75 % | 15 kW | 0.29–0.32 | 4.4–4.8 |
| 100 % | 20 kW | 0.28–0.31 | 5.6–6.2 |
Runtime per fill. Tank sizes vary by make; take 90 litres as an illustration. With 10 litres kept in reserve, 80 litres last roughly 17 hours at 75 % load (about 4.6 L/h) and 25 hours at 50 % (about 3.15 L/h). Running for hours at 3–4 kW, such as night lighting only, wastes fuel and fouls the engine; see light-load running and wet stacking.
Monthly fuel worksheet
Fill in your hours and load, then multiply the litres by the current diesel rate.
| Line | Example (workshop) | Your site |
|---|---|---|
| A. Generator hours per working day | 3 h | |
| B. Working days per month | 26 | |
| C. Hours per month (A × B) | 78 h | |
| D. Expected average load, kW | 10 kW (50 %) | |
| E. Litres per hour from the table | 3.1 L/h | |
| F. Litres per month (C × E) | about 242 L | |
| G. Add weekly test runs (about 1 L each) | 4 L | |
| H. Monthly diesel, litres (F + G) × current rate | about 246 L × rate |
Single phase or three phase at 25 kVA (and what “2 phase” means)
Three-phase 415 V is the standard at 25 kVA: workshops and restaurants have three-phase motors. A single-phase 25 kVA set suits only a premises that is single-phase throughout; it delivers 108.7 A at 230 V, needs heavier cable and changeover, and fewer makes build it. “2 phase” generators do not exist as such; the phrase usually means a load across two phases of a three-phase supply, typically a transformer welder, which is exactly what unbalances a set.
Imbalance limit. Makers typically allow 10–20 % between the most and least loaded phases, and no phase may exceed about 8.3 kVA (34.8 A). Feeding a single-phase premises from a three-phase 25 kVA set uses only about a third of it.
Auto-start on a 25 kVA set
“With auto start” means two items that should both appear on the quotation: a controller that accepts a remote start signal, and an AMF panel that senses the mains and operates the changeover, usually two interlocked four-pole contactors of about 40 A so the set can never feed back into the DISCOM supply.
Include a battery charger. In a workshop, add a timer so heavy machines do not restart the instant the set takes over. Changeover wiring is for a licensed electrician only.
How the price of a 25 kVA set is worked out
Two 25 kVA quotations can differ widely and both be fair, because they describe different machines and scope. The diesel generator price guide covers the general drivers; at 25 kVA these matter most:
- Single or three phase. Three-phase is the volume build; single-phase narrows the makes and may lengthen delivery.
- Make and engine. Three or four cylinders, naturally aspirated or turbocharged, mechanical or electronic governing: these decide how the set takes a compressor start or welder, copes with heat, and uses fuel.
- Alternator frame. A larger alternator on the same engine reduces dip on motor starts and welding; worth it in a fabrication shop.
- Canopy. The acoustic canopy is standard under CPCB IV+; build quality, corrosion protection and access still differ.
- Manual or auto-start. Key start costs least; an auto-start controller with AMF panel and contactor changeover adds cost and removes the need for someone on call.
- Battery, controller, tank and warranty. Battery capacity, alarms and hour logging, tank size and warranty terms all move the figure.
- New, used or rent. Used sets are priced on make, hours and condition; refurbished includes the rebuild and warranty; rental depends mainly on duration.
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Buy new, buy used or rent a 25 kVA set
The route depends on running hours and how long you need the set. See used and refurbished generators and generator rental rates.
| Your situation | Running hours per month | Duration of need | Usually the best route |
|---|---|---|---|
| Owned workshop or restaurant on a weak feeder, daily outages | 60 hours and above | Years | New set, sized with welding and motor starts in mind |
| Owned premises with occasional outages; standby only | Under 20 hours | Years | Refurbished set with warranty, or new if you want the latest controller and full warranty |
| Rented shed or commercial floor, lease of two to three years | Any | 2–3 years | Used or refurbished set you can move or sell on, or long-term rental |
| Fit-out, new shop waiting for its electricity connection, or construction | Many hours a day | Weeks to a few months | Rental |
| Tight budget, heavy duty | 60 hours and above | Years | Refurbished, load-bank tested, with warranty |
For rental, the availability of a 25 kVA set for your dates is confirmed when you ask.
Installation and site needs in Hyderabad
| Item | Typical for 25 kVA (approximate; the make decides) |
|---|---|
| Canopy size | About 2.0–2.4 m long, 0.9–1.1 m wide, 1.3–1.6 m high (about 6.5–8 ft long) |
| Weight with base tank | About 0.8–1.1 tonnes, plus fuel |
| Space including clearance | About 1 m on each long side, 1.5 m at the radiator discharge end and 1 m at the other: roughly 4.5–5 m × 3 m |
| Plinth | Level RCC plinth larger than the canopy by about 150 mm all round; raise it above the worst monsoon water level on your site |
| Breaker and cable | 40 A four-pole; 10 sq mm Cu or 16 sq mm Al four-core armoured for short runs; check voltage drop on longer runs |
Weight and handling
At around a tonne, the set is lifted only by the canopy lifting eye, or on forklift pockets where fitted. Check that a truck and hydra crane can reach the spot; many older workshop lanes are too narrow for a crane beside the truck. Terrace installation needs a structural engineer’s check and a crane with enough reach.
Exhaust, earthing, heat and water
- Exhaust: upward or away from neighbours, shop fronts and AC or kitchen fresh-air intakes, never at head height into a lane.
- Earthing: separate body and neutral electrodes, tested; see DG set earthing installation.
- Summer heat: Hyderabad afternoons reach the low-to-mid 40s °C in April and May, hotter inside a sunlit canopy, and output is derated above the data sheet’s reference ambient. Plan no more than about 16 kW then; see generator summer precautions.
- Monsoon: raise the plinth above local flood level, seal cable entries, keep battery and panel above the water line.
Worked example (illustrative): a fabrication shop on the city’s edge
Illustrative case. A gate-and-grill shop on three-phase supply loses power about three hours on most working days. Is 25 kVA enough? Working at the input to each load:
| Load | Input kW | kVA | Phase |
|---|---|---|---|
| Lighting, fans, office | 1.5 | 1.58 | R |
| Office inverter AC, 1.5 ton | 1.4 | 1.47 | Y |
| Air compressor 5 HP, DOL (3.7 kW ÷ 0.85) | 4.35 | 5.3 | 3-phase |
| Pedestal drill 1 HP, one at a time | 0.96 | 1.2 | 3-phase |
| Inverter welder 200 A, three-phase | 6.3 | 7.0 | 3-phase |
| Hand grinder, one at a time | 1.0 | 1.1 | B |
| Total | 15.5 | 17.65 |
Alternator loading = 17.65 kVA ÷ 25 kVA = 71 %
Compressor DOL start ≈ 5.3 kVA × 6.5 = 34.5 kVA = 1.38 × set rating → dip of roughly 15 %
Phase balance. The three-phase loads add 5.3 + 1.2 + 7.0 = 13.5 kVA, or 4.5 kVA per phase. Adding the single-phase loads gives R 6.08, Y 5.97 and B 5.6 kVA, all inside the 8.3 kVA per-phase limit. The spread is (6.08 − 5.6) ÷ 5.88 average = 8 %, within the usual 10–20 % allowance.
Fuel. Welding is intermittent, so the average is nearer 10 kW, about 3.1 L/h: 78 hours a month uses about 242 litres.
Decision. 25 kVA fits, with three rules on the panel door: one welder only, no cut-off saw while welding, and no welding for the first minute after changeover so the compressor starts on a light set. A second 5 HP compressor (about 4.4 kW more) would take the load to about 20 kW, and a 400 A welder well beyond it; either calls for 30 kVA or a soft starter.
Pre-delivery and handling checklist for a 25 kVA set
Most delivery-day delays come from access and readiness, not the set.
- Truck route checked: lane width, overhead cables, gate width and height, heavy-vehicle timings.
- Firm standing for a hydra crane beside the truck, with reach to the plinth; terrace sites have the structural note.
- Plinth cured and level, above monsoon water level, anchors as per the make’s drawing.
- Clearances marked (1 m sides, 1.5 m radiator end) and exhaust direction agreed with neighbours.
- Body and neutral earth pits ready and tested.
- Cable route measured; 40 A four-pole breaker and cable size confirmed for the length.
- AMF panel or changeover position fixed; licensed electrician booked for termination.
- First diesel fill arranged; welding and motor-starting rules written for the panel door.
Common mistakes
- Running a transformer-type arc welder across two phases of a 25 kVA set; it unbalances the alternator and trips or damages it.
- Planning to load the set to its full 20 kW in a workshop; with motor starts and May afternoon heat, about 16 kW is the comfortable working limit.
- Letting the compressor, welder and fixed-speed ACs all restart at the instant of changeover instead of staggering them with timers.
- Booking delivery without checking lane width and crane access for a set that weighs around a tonne, so the truck arrives and cannot unload.
What to send us
To price a 25 kVA set, tell us whether you want to buy new, buy used or rent; single or three phase; auto-start with an AMF panel or manual start; the site location, in Hyderabad or outside; your load list, especially compressors, welders, motors with their HP and ACs, or photographs of the distribution board; the delivery date; and, for rental, how long you need the set. Use the generator sales enquiry, or WhatsApp the details and photographs.
Questions buyers ask about 25 kVA generators
What is the price of a 25 kVA generator in Hyderabad?
There is no single figure, because the price changes with the make and engine, single or three phase, manual or auto-start with an AMF panel, tank size, warranty and whether you buy new, buy used or rent, and generator prices themselves change from day to day. A new-set quotation excludes GST, transport and installation, which are shown separately. A rental rate covers the generator only; transport is at actuals and in your scope, and cable or an operator are extra if you need them. Send us the phase, auto-start or manual, site location and load list on WhatsApp or call 98852 01608 and we will send the price.
How much diesel does a 25 kVA generator use per hour?
Approximately 3.0–3.3 litres per hour at half load (10 kW), 4.4–4.8 litres at 75 % load (15 kW) and 5.6–6.2 litres at full load (20 kW). At quarter load it uses about 1.8–2.1 litres per hour, which is less efficient per kWh. The make’s data sheet gives the exact figures.
How many ACs can a 25 kVA generator run?
About 7 to 8 fixed-speed 1.5-ton split ACs, or about 9 to 10 inverter units, spread evenly across the three phases with only light other load. The limit is each phase, which carries about 6.7 kW. Fixed-speed ACs must restart one after another after a changeover, or their combined starting current can trip the set.
How many amps is a 25 kVA generator?
A three-phase 25 kVA set at 415 V gives 34.8 A per phase at full load (25 × 1.391). A single-phase 25 kVA set at 230 V gives 108.7 A (25 × 4.348), though single-phase builds are uncommon at this size.
Can a 25 kVA generator run a welding machine?
One three-phase inverter welder of about 200–250 A, yes, if it is not used while the compressor is starting and other load is moderate. A transformer-type arc welder connected across two phases should not be run on a 25 kVA set, because it unbalances the alternator.
How much does a 25 kVA generator weigh?
Approximately 0.8 to 1.1 tonnes with its base tank, before fuel, and about 2.0–2.4 m long. The exact weight and dimensions depend on the make; plan for crane lifting and check access before delivery.
Is a second-hand 25 kVA generator available?
Used and refurbished sets are offered from 15 kVA to 2,000 kVA, so 25 kVA is within the range; what is available at a given time varies. Every set is load-bank tested before sale. Refurbished sets carry a six-month warranty (rubber and plastic parts, consumables, fuel damage and overload excluded); used sets sold as-is come with an inspection report and no warranty.
Can I rent a 25 kVA generator in Hyderabad?
Yes. Tell us the dates, the site and whether you need cable or an operator; the availability of a 25 kVA set for your dates is confirmed when you ask. The rate covers the generator; transport is at actuals and in the customer’s scope.
Related pages
- 15–50 kVA generators: sizing a small system
- 20 kVA generator in Hyderabad
- 30 kVA generator in Hyderabad
- Diesel generator price guide
- AMF panels and auto-start
- Used and refurbished generators
- Generator full-load current chart
- Generator on rent in Hyderabad
Technical content reviewed by D. Srinivas Reddy, Managing Partner and service engineer. Last updated 5 November 2026.