Temporary or permanent acceptance of containerized generator sets on board DNV GL classed vessels

A containerized generator set (CGS) covers the vessel’s need for electrical power when the vessel’s own CGS has been damaged, or provides additional power for special cargo/projects. With this news, you will gain an overview of the different acceptance criteria for CGS installations on board DNV GL-classed vessels.


Relevant for design offices, shipyards, suppliers, owners/managers and flag states.


If the CGS is installed to temporarily replace one of the vessel’s own generator sets due to damage, no formal approval is required. Class may accept some deviations from regular requirements should the CGS be installed for just a short period due to unforeseen damages.


  • After the review of the relevant documentation (see table 1 in appendix) and a survey of the temporary installation, a Condition of Class (CC) will be issued with a validity of maximum three months.
  • The temporary installation of a CGS may lead to certain notations being restricted based on an evaluation of the requirements regarding redundancy, automation, monitoring, etc. (e.g. E0, AUT, DYNPOS).
  • Ship owners and managers generally do not need to apply for flag exemption for temporary installations. For example, there is no need for exemption regarding MARPOL/EIAPP requirements. However, for SOLAS, the flag must grant an exemption for some deviations, such as an unsuitable location for the arrangement on deck or a non-approved fire extinguishing system.


Although the CGS units supplied on the market today normally meet the applicable criteria, their individual integration within the ship’s systems and the location of the container must be given special focus. 

In order to accept a CGS providing replacement power for a temporary installation, the following aspects need to be addressed. Please note that the criteria below are based on a CGS engine power of more than 375 kW; if the engine is smaller, the CGS is not considered a Machinery Space of category A and some criteria may be relaxed or waived.

Arrangement location

  • The CGS shall be located in a position that fulfills the SOLAS requirements to the greatest possible extent. This usually implies: 
  • The CGS is positioned in alongship direction in a non-hazardous, sheltered area.
  • For tankers, the CGS is located outside of cargo areas.
  • For ships certified to carry dangerous goods, the CGS is located at least 3 m away from the cargo areas, unless the CGS is a class A-60 insulated type.
  • The CGS is not located directly adjacent to, above or below accommodation spaces unless insulated to the A-60 standard.
  • The location of the CGS on board passenger vessels is subject to approval.
  • Ventilation inlets and outlets are preferably located not less than 4.5 m above the freeboard deck.
  • Container unit access openings are weather-tight to the best possible extent.
  • The CGS is securely fastened to the vessel’s deck, taking into consideration the position of deck stringers and stiffeners

Generator driver

Typically, the generator driver is a diesel engine. If not, please contact DNV GL for further guidelines.

  • The diesel engine shall be of proven design and should be suitable for the marine environment, preferably documented through a class society’s product certificate, type approval or similar.
  • The diesel engine shall be SOLAS-compliant with respect to the insulation of hot surfaces, shielding of high pressure fuel piping and fuel oil leakage alarm where jacketed fuel piping is installed.
  • The engine does not need to have an EIAPP certificate.


  • If the CGS is to act as one of two independent power sources as required by SOLAS, the generator shall have a rating which is sufficiently high for it to act as a single source of power during normal seagoing conditions.
  • The generator rating shall be less than or equal to the generator it replaces.
  • Generators exceeding the original generator’s rating may be acceptable after formal approval of the following:
  • Updated single line diagram for the power distribution system with changes/modifications clearly indicated. Information regarding the cross section, cable size, setting of circuit breakers and overcurrent and short circuit protection shall be shown on the drawing.
  • Updated load balance.
  • Short circuit calculation.
  • Selectivity analysis for all new installations, showing the selectivity between the generator breaker (if newly installed) and largest outgoing consumers.
  • Making/breaking capacity of new and existing (if capacity has increased) circuit breakers.

Fire safety

  • A fire detection system with an alarm audible and visible at a continuously manned station shall be installed.
  • An approved fixed fire extinguishing system shall be installed, operable from outside the container. Alternatively, non-approved fixed firefighting systems, documented to be relevant for their application, can be installed, provided an exemption has been obtained from the flag state.
  • Firefighting to be feasible from outside the container.
  • Two means of escape shall be arranged, unless considered unreasonable for a smaller CGS.
  • At least one portable fire extinguisher shall be arranged near each entrance to the container.
  • All ventilation to be able to be closed or shut off from outside the container.


  • The piping systems between any of the vessel’s tanks and the CGS and within the CGS are to consist of fixed piping. Connections between the vessel’s piping and piping systems in the temporary unit may be arranged with short flexible hoses, including couplings, type approved for their intended use.
  • If a tank container is installed in the vicinity of the CGS for the purpose of serving the CGS, a flexible hose connection may be accepted, provided that adequate protection is applied.
  • Materials, hoses and pipe connections are in general to be in compliance with DNV GL Rules.
  • Quick-acting shut-off valves are to be provided in way of connections below the top of fuel tanks containing more than 500 litres when these are open during normal operation.
  • Quick-acting shut-off valves are also required in fuel supply lines led through the engine room boundary when these are open in normal operation.
  • Controls of quick-acting shut-off valves are to be located in an accessible position at a safe distance from the unit.
  • Filtering is to be provided in fuel lines to the engine.
  • Air and sounding pipes to fuel tanks are to be led to open air.
  • A low level alarm for the CGS service tank is to be provided.


  • Cables shall be type approved or case-by-case approved.
  • The generator cable shall have short circuit protection at both ends.
  • Power cables should be routed as per class requirements.
  • Chargers for CGS units with battery-powered starts need to be powered from the vessel’s main supply, or alternatively an inspection routine is to be established.
  • Emergency stops for pumps and fans to be provided with an activation point outside the CGS.

Control and monitoring

- As a minimum, the following alarms shall be provided:

  • HP fuel oil jacket pipe leakage 
  • Starting air pressure (if applicable) 
  • L.O. pressure and temperature 
  • Turbocharger speed (if power >1000 kW) 
  • Exhaust gas temperature 
  • Cylinder cooling water pressure and temperature 
  • Engine overspeed 
  • Crankcase explosive condition (engines >2250 kW and bore >300mm)

- Alarms shall be connected to the main alarm system as individual or common alarms.

  • For E0/AUT vessels, when connected as a common alarm, a sub-system showing the detailed alarms shall be installed locally.

- For E0/AUT vessels, an alarm condition from the CGS shall initiate an alarm on the bridge.

Pollution prevention

In locations where oils spill can be expected to occur, a drip tray or coaming is to be provided.

If the CGS’s service tank is not provided with a high-level alarm audible at the control position of the fuel transfer pump, a written procedure for fuel transfer is to be available.

Final on-board testing

After installation, the following items are to be tested:

-Full load test of the engine and generator. 

  • The engine test load shall be as high as practicable, but no lower than 80% of the rated engine power, and be maintained sufficiently long for all parameters to stabilize.
  • If the CGS is considered to be one of two independent power sources, the generator load shall be the normal seagoing load or 80% of the rated engine power, whichever is the highest.

- If parallel-running facilities are provided, parallel running shall be demonstrated.

- Generator and switchboard testing.

  • Dynamic tests such as voltage regulation, speed governing and load sharing shall be carried out to verify that voltage and speed regulation under normal and transient conditions is within the limits given in the DNV GL Rules.

- Generator and switchboard protection systems are to be tested as follows:

  • Testing of overload protection.
  • Reverse power protection.
  • Overcurrent and short circuit protection.
  • Other protection such as earth fault, differential, undervoltage, overvoltage (if applicable).
  • Verification and testing of engine control and monitoring including, as a minimum, the connection to the vessel’s alarm system and overspeed protection.

- Verification and testing of fire detecting system.

- Detailed instructions for operation of the system to be posted locally and on the main switchboard panel, and verified during the testing.

Permanent installation for additional power

Contrary to temporary installations, which are needed due to unforeseen problems and to enable trading, CGS installations for additional power are planned alterations and will be treated as a permanent arrangement subject to approval by DNV GL in accordance with applicable DNV GL Rules and statutory requirements (see table 1 in appendix for the minimum documentation needed for review and approval). If the additional power is not connected to the ship’s main grid, some requirements for approval may not be applicable. 

EIAPP compliance shall be ensured in accordance with MARPOL Annex VI. Alternatively, exemptions for any deviations from EIAPP compliance shall be obtained from the flag state. 

The applicable documentation (see table 1 in appendix) has to be submitted through the local station or the KAM (Key Account Manager) prior to installation and final testing on board the vessel.


Whenever considering the installation of a CGS on board a DNV GL-classed vessel, it is recommended that you contact us in order to evaluate the need for approval and, if approval is not required, the applicable acceptance criteria.


Table of requirements


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