What Happens During Generator Commissioning Before Handover?

A generator that has been delivered and bolted down is not yet a power system. Between installation and handover sits commissioning: the structured process of verifying that the generator and everything connected to it have been installed correctly, configured as intended, and proven ready to carry the site's load.

Skipping or rushing this stage is how problems stay hidden until the first real power failure, which is the worst possible moment to discover them. Here is what a proper commissioning process covers.

Pre-commissioning inspection

Before anything is started, the installation itself is checked against the design. Typical items include:

• Mounting, alignment, and vibration isolation of the generator set
• Fuel lines, day tank, and bulk tank connections checked for leaks and correct routing
• Coolant and lubrication levels, hoses, and clamps
• Exhaust routing, supports, and clearance from combustible materials
• Ventilation openings and airflow paths free of obstruction
• Electrical terminations torqued, cable sizing verified, and earthing in place
• Battery condition and charger operation

This stage catches installation errors while they are still cheap to fix.

First start and running checks

The engine is started, usually off load first. Engineers monitor oil pressure, coolant temperature, charging voltage, frequency, and output voltage, and listen for anything abnormal. Protective shutdowns such as low oil pressure, high coolant temperature, and overspeed are tested to confirm the controller actually stops the engine when it should. Alarms are verified at the control panel.

Load testing

Running unloaded proves very little about how a generator will behave when the site actually draws power. During commissioning, the set is run under load, either using the building's own load or a resistive load bank, and stepped up in stages while voltage and frequency stability, cooling performance, and fuel delivery are observed. This is also where engine exhaust temperatures and alternator behavior under real demand are confirmed.

Controlled load testing is a large enough subject to deserve its own article, and we cover it separately on this blog.

Transfer and changeover testing

For standby installations, the generator is only half the system. The automatic transfer switch or changeover arrangement must detect a utility failure, signal the generator to start, transfer the load, and transfer back when mains power returns. Commissioning simulates a utility failure to prove the full sequence end to end, including start delays and return timers. For more on how this works, see our article on ATS vs manual changeover after a utility failure.

Documentation and handover

Commissioning ends with a record, not just a working machine. A complete handover package typically includes the commissioning report with recorded test values, as-built drawings, operating and maintenance manuals, the recommended service schedule, and warranty documentation. Site operators are briefed on routine checks, alarm responses, and who to contact for service. From handover onward, the recorded commissioning values become the baseline that future maintenance readings are compared against.

Why Commissioning Matters

Before the generator is put into service, commissioning assists in locating installation and configuration problems. It verifies that, under the testing conditions, the generator, controls, transfer system, and auxiliary equipment function as intended.

Additionally, it offers recorded test findings that can be used to assist warranty-related records, maintenance, and troubleshooting in the future.

At METS Energy, installation and commissioning are part of our wider approach to reliable power. Our team supports projects from site preparation and electrical integration through testing and final handover.

Planning a new generator installation? Explore our Installation & Commissioning services or contact our team at +961 70 801 401 or sales@metsenergy.com.