Choosing a diesel generator for a factory requires more than matching the generator's kW rating to the facility's total electrical load. Factory power systems often include motors, compressors, pumps, production lines, HVAC equipment, and other loads with different starting and operating characteristics.
A practical selection should consider the factory's load profile, operating schedule, generator duty, motor-starting requirements, installation conditions, and local regulations. The goal is to choose a generator configuration that fits the actual application rather than simply selecting the largest available model.
1. Assess the Factory's Power Requirements
Start with the factory's electrical load data. List the main equipment and determine its running power, peak demand, starting current, voltage, phase, and expected operating schedule.
Particular attention should be given to motors and other inductive loads. Large motors can require significantly more power during startup than during normal operation. If this starting demand is not considered, a generator may experience excessive voltage or frequency dips even when its continuous kW rating appears sufficient.
For example, factories may consider generator sizes such as 100 kW, 200 kW, 500 kW, or 1,000 kW. However, the appropriate size depends on the actual load profile rather than the number on the equipment nameplate.
For initial product research, buyers can review the industrial generator product range and the diesel generator sets available from the supplier. Model datasheets should then be requested for detailed compar
2. Match Generator Rating to the Factory's Duty
Generator ratings should be evaluated together with the intended operating pattern.
A factory that uses a generator mainly during utility outages may have different requirements from a facility that expects the generator to operate for extended periods. Ask the supplier to clarify the applicable standby, prime, or continuous rating and the conditions under which each rating applies.
Also consider:
- Expected annual operating hours
- Required backup duration
- Load variation during production
- Number and size of motors
- Future production expansion
- Required redundancy
For facilities where power continuity is particularly important, two smaller generator sets may provide greater operational flexibility than one large unit. Multiple units can also allow part-load operation and maintenance with less disruption, although paralleling and synchronization equipment may add complexity.
3. Check Motor-Starting and Electrical Performance
Motor starting is one of the most important considerations when selecting a factory diesel generator.
Production equipment such as air compressors, pumps, conveyors, refrigeration systems, and large machine tools may create high starting demand. Instead of comparing generators only by rated kW, ask suppliers for information on:
- Starting kVA or motor-starting capability
- Voltage and frequency regulation
- Alternator type
- Acceptable load step
- Generator response to large motor loads
- Compatibility with variable-frequency drives and other electronic equipment
A load study or load-step analysis can help determine whether the proposed generator can handle the factory's largest starting loads without unacceptable electrical disturbances.
For example, ZLN Power's 200kW Shangchai diesel generator set lists a 200 kW output and provides model-specific technical information that can be used as a starting point for supplier comparison. Final suitability should still be confirmed against the project's actual load data.
4. Consider Installation and Site Conditions
The generator's physical environment can affect both performance and installation cost.
Before purchasing, evaluate:
- Available installation space
- Ambient temperature
- Site elevation
- Ventilation and cooling
- Exhaust routing
- Noise requirements
- Fuel storage
- Grounding
- Maintenance access
- Transportation and lifting requirements
Altitude and ambient temperature may affect engine performance, so the supplier should confirm whether any output derating applies to the installation location.
For indoor installations, ventilation and exhaust design deserve particular attention. The generator room must provide adequate combustion air and remove engine heat and exhaust gases. Outdoor installations may require weatherproof or sound-attenuated enclosures depending on the site.
5. Plan the ATS and Control System
A diesel generator is normally part of a larger backup power system rather than a standalone piece of equipment.
For standby applications, an automatic transfer switch (ATS) can detect utility failure and transfer the designated electrical load to the generator. The Pacific Northwest National Laboratory's standby generator guidance notes that ATS systems can initiate generator startup and transfer the load when the primary power source is unavailable.
During procurement, confirm whether the proposed generator package includes or supports:
- Automatic transfer switching
- Remote monitoring
- Emergency stop functions
- Generator protection
- Synchronization or paralleling
- Communication with the factory's control system
The required control configuration should be defined before ordering, particularly when the generator will be integrated with an existing electrical distribution system.
6. Review Emissions and Local Requirements
Environmental requirements should be checked before purchasing a factory diesel generator.
Diesel engines are compression-ignition engines, and applicable emissions requirements can vary according to engine size, installation type, operating conditions, and jurisdiction. In the United States, the U.S. EPA requirements for stationary compression-ignition engines address pollutants including NOx, particulate matter, sulfur dioxide, carbon monoxide, and hydrocarbons.
Buyers should therefore confirm:
- Applicable local emissions standards
- Required engine certification
- Air permits, if applicable
- Operating restrictions
- Exhaust treatment requirements
- Fuel requirements
- Required emissions documentation
For projects outside the United States, the relevant national and local regulations should be reviewed instead of assuming that U.S. requirements apply.
7. Compare the Complete Cost, Not Just Generator Price
The initial generator price is only one part of the purchasing decision.
A factory project should also consider installation, fuel consumption, ATS equipment, cabling, exhaust systems, fuel storage, commissioning, maintenance, spare parts, and expected operating hours.
When comparing suppliers, request a complete technical and commercial quotation covering:
- Generator model and rated output
- Engine and alternator specifications
- Standby/prime/continuous rating
- Fuel consumption data
- Motor-starting capability
- Control and ATS configuration
- Dimensions and weight
- Warranty and after-sales support
- Delivery and installation scope
- Required certifications and documentation
This makes it easier to compare different factory diesel generator configurations on a like-for-like basis.
Frequently Asked Questions
What size diesel generator does a factory need?
There is no single generator size suitable for every factory. The required capacity depends on running load, peak demand, motor-starting requirements, operating schedule, and whether the generator is intended for standby or prime power. A load assessment should be completed before selecting the final rating.
Is one large generator better than several smaller generators?
Not necessarily. A single large unit may simplify the system, while multiple units can provide redundancy, staged capacity, and more flexible maintenance. The better option depends on the factory's load profile, reliability requirements, available space, and budget.
Does a factory generator need an automatic transfer switch?
For many standby applications, an ATS is used to transfer selected loads between the utility supply and generator. The exact configuration depends on the facility's electrical system and backup strategy.
What should I ask a diesel generator supplier?
Ask for the generator's rating, engine and alternator models, fuel consumption, motor-starting capability, control system, dimensions, warranty, certifications, delivery scope, and recommended maintenance requirements. Project-specific technical confirmation is preferable to relying only on general catalog specifications.
Conclusion
Selecting a diesel generator for a factory should begin with the facility's actual electrical requirements rather than a predetermined generator size. Load characteristics, motor starting, duty rating, installation conditions, ATS integration, emissions requirements, and lifecycle costs all affect the final choice.
For procurement, a useful approach is to prepare the factory load data first, shortlist suitable generator models, request detailed datasheets and technical quotations, and then have the proposed configuration reviewed by the supplier and qualified electrical professionals.
This process can reduce the risk of choosing a generator that is oversized, undersized, or poorly matched to the factory's operating conditions.
