Choosing the right diesel generator starts with understanding your power requirements. Whether you need backup power for a warehouse, a retail facility or an industrial operation, the generator must match your electrical load, operating hours and site conditions.
In the UAE, high temperatures and dusty environments also affect generator selection. This guide explains what to check before buying a diesel generator and how to avoid paying for unsuitable capacity.
1. Define Your Power Requirements
First, determine when and how the generator will operate:
- Standby power: backup electricity during a utility outage.
- Prime power: the main electricity supply for regular operation with a variable load.
- Continuous power: electricity for sustained operation at a relatively constant load.
Temporary applications, such as construction projects and events, also need a suitable rating based on their operating hours and load profile.
Check the manufacturer’s rating definitions and operating limits. A generator’s standby rating should not be used as its capacity for regular prime-power operation.
2. Calculate the Equipment’s Running Load
List the equipment that needs to operate at the same time. Record its electrical input power in kilowatts (kW), using equipment specifications or measured consumption.
For example:
| Equipment | Running load |
|---|---|
| Lighting | 3 kW |
| Water pump | 2 kW |
| Refrigeration equipment | 5 kW |
| Ventilation system | 4 kW |
| Computers and communications | 2 kW |
| Total | 16 kW |
This gives you the running load, but it does not confirm the required generator size. Pumps, compressors and refrigeration equipment may need substantially more power during startup.
3. Account for Starting Loads and Future Expansion
Generator sizing must consider both normal operation and the largest load changes.
Before choosing a model, identify:
- which motors have high starting currents;
- whether equipment starts simultaneously or in stages;
- the motor starting method;
- acceptable voltage and frequency changes;
- any planned additional equipment.
A capacity margin can allow for future growth, but a fixed percentage cannot replace a starting-load assessment. For the 16 kW example above, the final generator size depends on the equipment’s starting characteristics and operating sequence.
Avoid excessive oversizing, too. Prolonged operation at low loads can contribute to wet stacking and carbon deposits in diesel engines. Ask the supplier about the model’s recommended operating load.
4. Understand kW and kVA Ratings
Diesel generator specifications commonly show both kilowatts (kW) and kilovolt-amperes (kVA):
- kW measures active power.
- kVA measures apparent power.
- Power factor relates the two.
The relationship is:
kW = kVA × power factor
For a generator rated at a power factor of 0.8, a 100 kVA rating corresponds to 80 kW. However, the connected equipment’s power factor may differ.
Check both the generator’s kW and kVA limits, along with the required voltage, frequency and phase configuration. Matching only one rating is insufficient for accurate selection.
5. Choose the Right Generator Enclosure
The enclosure should suit the installation location, noise requirements and maintenance access.
Common options include:
- Open generators: suitable for properly designed generator rooms or protected installations.
- Sound-attenuated canopy generators: a practical option where noise reduction and weather protection are required.
- Containerized generators: suitable for projects requiring a larger enclosure or customized installation features.
- Trailer-mounted generators: useful for mobile, rental and temporary applications.
A canopy reduces noise but does not eliminate it. Compare sound levels at the same measurement distance and operating load. Weather protection, ventilation, fire protection and fuel capacity should be checked against the actual specification.
6. Decide Whether You Need an ATS
An Automatic Transfer Switch (ATS) allows the electrical load to transfer between the utility supply and the generator automatically.
In a compatible automatic system, a utility failure triggers generator startup. Once generator power is available and stable, the load transfers. When utility power returns and stabilizes, the system transfers the load back.
An ATS is useful for unattended backup applications, but startup and transfer take time. Equipment that requires uninterrupted power may also need a UPS or another suitable continuity solution.
7. Check Suitability for UAE Site Conditions
When selecting a diesel generator in the UAE, confirm its performance under the conditions at your installation.
Discuss the following with your supplier:
- maximum expected ambient temperature;
- radiator and cooling-system capability;
- airflow and ventilation;
- dust exposure and filtration;
- humidity and corrosion protection;
- exhaust routing and maintenance access.
High temperatures can reduce available output, depending on the model and its rating conditions. Ask for the generator’s usable capacity at your site temperature and whether derating is required.
8. Compare Service Support and Ownership Costs
Before purchasing, ask the supplier to confirm:
- fuel consumption at your expected load;
- tank capacity and estimated runtime;
- maintenance requirements;
- availability of genuine spare parts;
- local technical support;
- warranty coverage and exclusions;
- installation and commissioning scope.
Compare what each quotation includes. A lower purchase price may exclude equipment or services your project needs.
Need Help Choosing a Diesel Generator?
The right generator should meet your running and starting loads, suit your operating mode and perform reliably under your site conditions.
For a project-specific recommendation, share your equipment list, installation location, expected operating hours and future expansion plans with MYSPAN.
Contact MYSPAN to discuss diesel generator options for your project in the UAE.