In short. The right generator follows from your load, duty, site and rules. Work through the steps below, then send the details to us. We will size the set properly rather than selecting from the connected load alone.
Step 1: define the load
- List equipment with kW or kVA and power factor.
- Note the largest motor and its starting method. See motor starting.
- Identify UPS, drives and other nonlinear loads. See UPS and nonlinear loads.
Step 2: define the duty
| Duty | Meaning |
|---|---|
| Standby | Runs during utility failure; few hours per year |
| Prime | Main source with variable load |
| Continuous | Constant load, long hours |
| Rental / temporary | Short-term need. See rental power |
Step 3: size
Size for running load, starting surge, site conditions and growth. See generator sizing, ambient derating and altitude derating.
Step 4: rules and fuel
Check emission rules for your location and fuel options. See emissions overview and cleaner fuels.
Step 5: system
Decide on ATS or AMF, parallel operation, redundancy and enclosure. See N+1 and synchronisation.
Step 6: commissioning and support
Plan commissioning, load bank testing and AMC.
What to send us
Load list, duty, location, fuel, space, noise limits and timeline. Send your application details or call 098852 01608.
A worked example, start to finish (illustrative)
A commercial building in Secunderabad needs backup for lifts, fire pumps, lighting, IT and part of the air conditioning.
| Step | Decision | Result |
|---|---|---|
| 1. Load | Essential load list after demand factors | 380 kW running, 0.85 power factor, so 447 kVA |
| 2. Duty | Standby, outages of a few hours, occasional long outages | Standby rating applies |
| 3. Size | Largest motor 55 kW star-delta, summer ambient 45 °C, growth 15 percent | Approximately 447 × 1.15 ÷ 0.95 ≈ 540 kVA required, so a 625 kVA class set is shortlisted and the motor start is checked |
| 4. Rules and fuel | Check current emission and noise rules for the set and site | Confirm applicable norms before ordering |
| 5. System | ATS, single set, space for a second | Provision for future paralleling |
| 6. Commissioning | Load bank test, service contract | Documented acceptance |
Choosing between standby, prime and continuous
- Standby: runs only during outages. Highest rating for the same machine, limited annual hours.
- Prime: runs as the main source with variable load. Lower rating and an overload allowance.
- Continuous: runs at constant load for unlimited hours, lowest rating.
Using a standby-rated set for long running hours shortens its life. Match the class to the duty and confirm definitions with the maker.
Single set, parallel sets or hire
| Option | Best when |
|---|---|
| Single set | Modest load, an outage of hours tolerable, budget limited |
| Parallel sets (N+1) | Critical load, growth expected, maintenance without outage needed |
| Rental | Temporary need, event, shutdown or bridging a repair. See rental power |
Fuel and emissions
Diesel remains the common choice for backup. Cleaner-fuel options, including dual fuel and emission-control retrofits, depend on duty and regulation. Confirm current official notifications for your site. See cleaner-fuel generator systems and emissions and power transition.
Site, noise and ventilation
Generator rooms and canopies need combustion air, cooling airflow and an exhaust path. Poor ventilation derates a set more than altitude does. Acoustic enclosures and silencers meet noise limits at the boundary. Hyderabad’s dust and monsoon humidity affect filters and electrical enclosures.
Common mistakes
- Sizing on connected load instead of demand.
- Ignoring the largest motor start.
- Choosing the engine and forgetting the alternator reactance.
- Leaving out fuel storage and delivery planning.
- No load bank testing at handover.
The master engineering question
If the utility fails now, will this set start, carry my real load and keep running for as long as I need it?
Questions buyers ask
Can I choose by kVA alone?
No. Starting loads, duty and site conditions matter.
New or used?
Depends on duty, rules and risk; assess condition and compliance.
Do I need an ATS?
For automatic changeover, yes.
Can you size from my bill?
Bills help; a load list is better.
Guidance only. Final selection needs site data.