Testing and Commissioning of Diesel Generator Set


Testing and commissioning of the diesel generator set in compliance with the specified tolerance and limitations outlined with industrial standards, guidelines with reference to the project specification, manufacturer’s instructions, and authority requirements.

The entire Testing and Commissioning of Diesel Generator Set shall be performed by the supplier’s specialist/third party-experienced engineer.


The purpose of this method statement is to outline the method of testing and commissioning of the following:

  • Diesel Engine and Auxiliaries
  • Generator/Alternator
  • Instrumentation/Control
  • Fuel Storage and Transfer
  • Air intake and Exhaust System

Specialist supplier/third-party team, an experienced commissioning engineer will thoroughly inspect all the working drawings and specification, and become totally familiar with all systems and the design intent.

Application Location

Diesel Generator Room

General Requirements

Specialist Equipment & Liaison

An engineer available to liaise with the manufacturers commissioning engineers and assist with checking pressure rates setpoints etc. as necessary.

Items of equipment to be commissioned by specialists include, but are not limited to the following:
The diesel generator set and support system.


Before commencing commissioning works, the following information/items will be made available.

Full set of up-to-date installation drawings and system schematics detailing all systems to be commissioned.

Capacity and schedule.

Commissioning, operating and maintenance instruction’s equipment.

Any special operating keys, tools, etc.

Access to all areas; plant etc. through doors, risers, false ceilings, etc.

Safety Precautions

Safety awareness should be followed during the execution of testing & commissioning works.

Secure Work Permit in conjunction with the approved safety plan and Risk Assessment before Starting the work.

Usage of proper tools, instrument to be handled by the authorized person only.

Usage of proper safety shoes, safety belts, safety helmets, gloves, goggles, mask, earplugs & any other safety accessories as required during commissioning works.

Guards of approved design shall be provided for all V-belts drives, coupling shafts and exposed rotating machinery.

Electrical power supply shall be isolated and panel switch gear shall be locked whenever carrying out work on any rotating equipment or electrical panels.

No commissioning works shall be carried out without adequate lighting available.

Approved Project Safety Plan & procedures shall be followed during execution of commissioning works.

Provide Warning Boards/ Tapes as required during Testing & Commissioning of Diesel Generator Set.

Preliminary Checks

State of the Building and System

  • Equipment installations as per approved layout and site requirements
  • Fuel supply connected and commissioned by infrastructural.
  • All panel termination fixed and ready for Commissioning.
  • Access available to all areas to be tested.


Diesel Generator Set-

  • Diesel Engine and Auxiliaries
  • Generator/ Alternator
  • Instrumentation/ Control
  • Fuel Storage and Transfer
  • Air intake and Exhaust System

Pre-Commissioning – Checks

Building & Services

• Building & Installation of main equipment as per approved drawing/ submittal. The site is clean from all/ any construction materials and debris.
• All necessary Building services are installed, commissioned, and in operation.
• Lighting/ Emergency lighting
• Electrical auxiliary supplies
• Water/Drainage

Generator Room – General

• Generator set is clean with all guards in place as approved drawing.
• Ensure there are no loose materials left around the diesel generator set.
Air ducts are clean and the path is clear with no obstruction.
• Control & maintenance positions are clear with no obstruction.
• Room is secured for “NO UNAUTHORIZED” access.

Generator Set

• Ensure the diesel generator set installed at the proper level as required/approved.
• All pipe works are installed and secured in place.
• Radiator is clean from dust and free from obstruction.
• Radiator air outlet connected to outlet duct properly.
• Check for any hot air re-circulation.
• Ensure the radiator top is accessible for coolant top-up.
• Pipework is complete and no damage.

Fuel Storage – Day Tank

• Tank installation done as per approved drawing/ specification.
• Ensure fuel inlet/return line is connected.
• Check for no valve in spill return
• Flexible connections to engine is well connected and no damage.
• Connections for fill, overflow and vent is completed.
• Tank content indicator gauge installed and clear.

Exhaust System

• Installation done as per approved drawing/ specification.
• Ensure no re-circulation of exhaust fumes
• Flexible connection to the engine connected and secured
• Ensure for enough support to prevent load on turbo-charger manifold
• Pipe work/ muffler supported well in right interval
• All pipe joints are welded/flange connect with proper gaskets. Exhaust exit directed away from the building/ personnel.
• Pipe network is lagged/ clad as required.
• All flammable materials are protected properly.

Ventilation & Attenuations

• Installation done as per approved drawing/ specification.
• Ensure air intake is at least I 50% area of inlet.
• Ensure the airflow direction is from alternator to radiator.
• Ensure the radiator outlet is ducted to louver.
• Installation must prevent hot air recirculation & rain ingress.

Electrical System General

• Installation done as per approved drawing/ specification.
• Auxiliary electrical supply customer wiring/ termination are completed.
• Grounding/ earthing system complete and tested.
• Utility power supply available as required.
• All small power & lighting circuits tested and complete.

Instrumentation/ Control

• Installation done as per approved drawing/ specification.
• All customer wiring terminations are completed.
• Field device & wiring is complete with termination.
• Interconnection to remote start is complete.
• Emergency stop controls wired and complete.

Switch Gear/ Change Over/ Transfer

• All switch gear installation done as per approved drawing/ specification. Ensure all cables installed, terminated and complete.
• All power connections complete with torque check.
• Voltage and phase rotation checked and ensure proper.
• Ensure all indications are correct and healthy.

Testing and Commissioning- Diesel Engine Start Up

Safety checks prior to start-up.
Ensure starting is inhibited.
Diesel generator set is clean and fully assembled.
Battery status is healthy and proper voltage is available.
Ensure the battery charger is in operational and charging.
No loose materials around generator set.
Controls and maintenance are unobstructed.
Warn personnel of impending equipment start up.
Initial start up.
Manual start up, idle run check.
Run in full speed check.
After completing speed checks set for rated speed.
Setting of desired voltage & frequency.
Check oil level, pressure, and temperature.
Ensure the radiator operation and any leakage of coolant.
Fuel supply is proper and no leakage.
Ensure exhaust system operation and smoke status.
Control calibrations checked.
Phase rotation checked.
Local stop/emergency & stop control checked.
Remote start/stop & emergency stop checked.
Load test performed.
Now generator can be checked with load available at site.
Variable load as per requirements.
Record the relevant readings during the load test.

Automatic Operation

Open the reference power supply to the startup panel and ensure the diesel generator set getting ON in stipulated time.
After successful automatic turn ON, now restore the reference power supply back to normal position.
Now ensure the diesel generator set goes OFF in the stipulated time delay set.
Ensure the proper transfer of power supply in switch gear as per electro-mechanical logic interlocks provided.
Record all relevant reading and indications in the commissioning format.
Ensure compliance to all manufacturer’s start-up and commissioning instructions, as applicable.

Witness Demonstrations/Completion

The commissioning engineer will ensure that the following works are carried out.

The final test and results are demonstrated to the accepting authority on a random spot check basis, and that repeatability.

All equipment final settings are permanently marked, speed gauge indicators, radiator/engine head hot water temperature using an agreed method.

Submittal of all records of data obtained during testing, in accordance with, and on the approved forms.

Preparation of test report and hand over certificated and duly signed by the main contractor and consultant.

Noise level acceptance test shall be carried out to meet requirements as specified.

Test Instrumentation

The following test instruments will be used for the commissioning and testing activities. These will be selected as having the maximum field measuring accuracy and being the best suited to the function being measured and will be applied as recommended by the manufacturer.

List of Instruments

The list of instruments that are used in the Testing and Commissioning of the Diesel Generator system.

Electrical Measurement

1Tong Tester (Analog) To measure current, voltage and Resistance
2Tong Tester (Digital) To measure current, voltage and Resistance
3Megger To measure the insulation resistance of cables, winding
4Phase DetectorTo check the sequence of phases
5Electrical Tool Kit

Mechanical Measurement

1IR ThermometerTo measure space temperature

Calibration Frequency

All the instruments are calibrated externally once in 12 months or as per the recommendation of the manufacturer whichever comes earlier and the records are maintained.

All are used under their allowable ranges and limits.

All equipment is stored in the service station under suitable environmental conditions when they are not in use and verified their accuracy at regular intervals.

Prior to the commencement of Testing & Commissioning activities, Test Certificates of all instruments will be submitted for Consultant approval.

Certificates will be available for presentation prior to the commencement of the works.

Commissioning and Standards Implemented

NFPA standards, guidelines with reference to project specification and manufacturer’s instructions.


Inspection request shall be raised promptly to Consultant m accordance with the approved documents.

Inspection shall be carried out as per approved documents.

Inspection shall be recorded in the approved checklist.

Reference Documentation

Manufacturer’s catalog

Approved submittal

Shop drawings

Safety Manual

Risk Assessment


Prepare as-built drawings where necessary to allow the client to amend his own drawings.

All the test results shall be recorded and the inspection request, ITP, and the forms used shall be signed by both the contractor and Consultant.

All permits shall be signed off and returned.

The Certificates for the completion of work shall be submitted to engineers for records.

Signed-off Pre-commissioning Checklists.

Commissioning Reports.

Calibration certificates of testing instruments.

Hand Over Certificate


Testing and Commissioning (T & C) Report

Inspection and Test Plan (ITP)

Risk Assessment