7 SOURCES OF ENERGY
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Statutory Documents - IMO Publications and Documents - Circulars - Radiocommunication and Search and Rescue - COMSAR/Circ.32 - Harmonization of GMDSS Requirements for Radio Installations on Board SOLAS Ships - (16 August 2004) - Annex - Guidelines for the Harmonization of GMDSS Requirements for Radio Installations on Board SOLAS Ships - 7 SOURCES OF ENERGY

7 SOURCES OF ENERGY

 7.1 Main source of electrical power

The main source of electrical power is defined as the ship's mains. All the basic and duplicated equipment should have an independent power supply from the ships mains. The battery charging arrangement used to charge any batteries associated with the reserve source of energy should also have an independent supply from the ships mains.

It is not advisable to provide the main source of electrical power to the GMDSS communication equipment through the battery charger. If a fault occurs in the battery charger, which renders it defective, it may not be possible to operate the equipment from the ship's mains. Batteries used in the reserve source of energy will become discharged eventually leading to loss of all power supplies.

(SOLAS 1974, as amended, chapter II and IMO resolution A.702(17), Annex, item. 2.3)

 7.2 Emergency source of electrical power

The emergency source of electrical power is defined as the emergency supply and is usually taken from the ship's emergency generator. SOLAS requirements for the emergency source do not apply to cargo ships of less than 500 gross tonnage (gt). All other SOLAS ships constructed on or after 1 July 1986 are required to have an emergency source of electrical power. It should be observed that the GMDSS requirements concerning the emergency source have been made compulsory only for ships constructed later than 1 February 1995.

The emergency source should be adequate to operate both the basic and duplicated equipment (if applicable) for the duration as specified in SOLAS chapter II, i.e. 18 hours on cargo ship and for 36 hours on passenger ship.

(SOLAS 1974, as emended, regulations II-1/42 and 43)

 7.3 Reserve source of energy

  • .1 The radio reserve source or sources of energy should meet the requirements set out in regulation IV/13 of SOLAS 1974, as amended, and in IMO resolutions A.694(17) and A.702(17), as applicable. It usually consist of rechargeable batteries and is used to supply the communication equipment in the event of failure of the ship's mains and emergency source of electrical power.

    All passenger ships irrespective of size and cargo ships of 300 gt. and upwards should have a reserve source or sources of energy for the operation of the basic equipment, and the duplicated equipment if such equipment is required.

  • .2 The changeover from the ship's mains or emergency supply to the reserve source of energy should be done automatically and in such a manner that both the basic and duplicated communication equipment will be connected simultaneously. Where the changeover is done manually, the switch should be readily accessible to the radio operator, clearly labelled and located on the navigation bridge. Such changeover should not result in the loss of data stored in memories.

  • .3 One bank of batteries may be acceptable if the capacity is sufficient to operate both the basic and duplicated radio equipment simultaneously. The battery capacity should also be sufficient to operate the gyro (if applicable), GNSS and emergency light.

  • .4 Any fault in the radio batteries or the battery charger should not affect both the basic and duplicated radio equipment and should not prevent the operation of the radio equipment from the ship's mains or emergency supply.

    .5 The reserve source of energy should be capable of operating the radio installation for at least:

    • .1 1 hour on ships provided with an emergency supply which is adequate to operate the radiocommunication equipment for a period of 18 hours on cargo ships and 36 hours on passenger ships; or

    • .2 6 hours on ships not provided with an emergency supply as outlined in .1 above.

(SOLAS 1974, as amended, regulations IV/13.2, 13.4, 13.5, 13.8 and IMO resolutions A.694(17), A.702(17), Annex, item 2.3 and COMSAR/Circ.16)

 7.4 Radio battery capacity

When defining the minimum required battery capacity, consideration should be given to the expected extreme temperatures for the location of the battery and reduction of its capacity during its lifetime in addition to the loads which are to be connected to it.

  • .1 The batteries should have enough capacity to operate all the GMDSS radio equipment for the specific times outlined in subsection 7.3.5 above. The total load for the entire radio installation should be calculated prior to the installation of any radio batteries for the reserve supply.

  • .2 Where the basic and duplicated radio equipment cannot be operated simultaneously, the battery capacity should be sufficient to operate the equipment with the highest power consumption.

  • .3 Where the basic and duplicated radio equipment are connected simultaneously the battery capacity should be sufficient to meet the average consumption of all connected equipment including any additional loads such as printers, VDUs etc.

  • .4 If the capacity requirement of radio batteries is to be maintained over their normal life cycle, an extra 40% capacity should be added to the minimum calculated capacity.

  • .5 When calculating discharge time the following guidelines may be of assistance:

    • .1 the capacity of a lead acid battery is normally quoted at 20 hours of discharge at an operational temperature of 20°C;

      .2 the capacity at 1 hour discharge is approximately 50% of the capacity at 20 hours discharge;

      .3 the capacity at 6 hours discharge is approximately 80% of the capacity at 20 hours discharge; and

      .4 for batteries other than the lead acid type the capacity at 1 hour discharge is approximately 60% of the capacity at 10 hours discharge and 6 hours discharge will be approximately 92% of the capacity at 10 hours discharge.

  • .6 The capacity of the radio batteries should be checked at intervals not exceeding 12 months when the ship is not at sea. One method of checking the capacity is to fully discharge and recharge the batteries using normal operation current over a period of 10 hours. Assessment of the charge condition can be made at any time, but it should be done without significant discharge of the battery when the ship is at sea. Another method could be to check the capacity by means of a battery tester, e.g. in connection with a radio survey.

(SOLAS 1974, as amended, regulation IV/13, IMO resolution A.702(17) and COMSAR/Circ.16)

Note: - When determining the battery capacity the following should also be taken into consideration:

  • - the battery is normally not fully charged;

  • - reduction of capacity due to ageing;

  • - reduction of capacity due to high or low temperatures; and

  • - reduction of capacity due to rapid discharge.

 7.5 Radio batteries

The batteries should be properly marked with type or construction, rated capacity, and installation date. The marking should be visible when the batteries have been installed and during their lifetime A label warning of explosion danger should be displayed near the installed batteries.

  • .1 Any type or construction of batteries (e.g. lead acid, alkaline, maintenance free, traction, semi-traction, etc.) may be used as reserve source or sources of energy, taking into consideration the environmental conditions of the location where they are installed.

  • .2 The battery should maintain its rated capacity when inclined at any angle up to 22 ½° in any orientation.

  • .3 All battery units should be securely braced so that they will not be dislocated by movement of the ship.

  • .4 An instruction manual which contains all necessary specifications of the batteries should be available on board. The information should include at least:

    • .1 capacity and temperature range within which the stated capacity is maintained for the specific operation period i.e. 1 hour or 6 hours;

    • .2 charging voltage and current limits in order to keep batteries fully charged while preventing overcharging;

    • .3 actual specific gravity of the electrolyte and/or cell voltages or the voltage of the fully charged battery;

    • .4 guidelines on how to carry out a controlled discharge test;

    • .5 methods of determining the condition of charge of the battery, e.g. check of specific gravity of electrolyte (acid density) or check of battery cell voltage/battery voltages by using an accurate measuring instrument in according with the battery manufacturer's specifications;

    • .6 requirement for ventilation; and

    • .7 requirement for maintenance.

  • .5 Equipment requiring a lower voltage than the total voltage of the battery bank should not be connected to a part of the battery bank.

  • .6 The batteries should be installed in the upper part of the ship, in an elevated position and as close to the radio equipment as possible.

  • .7 An outdoor located battery case should be avoided due to considerable temperature variation.

    Note: - Ideal location for the radio batteries is in a battery room with a constant temperature of approx. 20°C.

    The location should in general satisfy the manufacturers specifications with regards to temperature tolerance and environmental strain in accordance with IEC 60945 or other equivalent standards.

  • .8 Batteries of different types, different cell constructions, different capacities or different manufacturers should not be mixed in a battery bank.

  • .9 Batteries of different types and different cell construction should not be installed in the same location if they can affect each other.

  • .10 Sufficient ventilation for batteries should be provided, as required by the battery manufacturer.

  • .11 Electrical installations including battery chargers, located in the battery room, should be intrinsically safe.

  • .12 Sufficient space between batteries or battery banks should be provided in order to enable inspections and maintenance.

  • .13 The cabling from the batteries should be protected against earth and short-circuits and be appropriately fused and installed according to recognized international standards (IEC 60092-101 and IEC 60533). Battery cables should have sufficient dimensions to prevent voltage reduction at peak current consumption.

(SOLAS 1974, as amended, regulation V/13 and COMSAR/Circ.16)

 7.6 Uninterruptable power supplies (UPS)

A UPS is defined as a device which for a specific period of time supplies continuous power to radio equipment independent of any power failures in the ship's main or emergency source of electric energy. The UPS, installed as the reserve source or sources of energy, should meet the general requirements set out in regulation IV/13 of the SOLAS 1974, as amended, and in resolution A.694(17), as applicable, and should also comply with the following requirements:

  • .1 Comprise an automatic charger, complying with requirements set out in SOLAS regulation IV/13.

  • .2 Comprise rechargeable accumulator batteries, complying with the guidelines regarding automatic chargers.

  • .3 Provisions should be made for an aural alarm and visual indication at the position from which the ship is normally navigated, indicating any failure in the UPS which is not monitored by the alarm and indicators required by the guidelines regarding automatic chargers.

  • .4 The UPS should be operational within 5 seconds of switching on.

  • .5 The UPS should be so designed and constructed that it is protected against damage resulting from disconnecting the batteries or, with the battery disconnected, short-circuiting the UPS battery connections. If this protection is provided by electronic means it should automatically reset following removal of the open or short-circuit conditions.

(COMSAR/Circ.16)

Note: - If the UPS does not fulfil the requirements in accordance with SOLAS regulation IV/13 and IMO resolution A.702(17), two separate UPS systems should be installed; one for the basic radio equipment and one for the duplicated equipment.

The capacity of batteries used in UPS systems is normally stated at a discharge time of 10 hours. When discharging such batteries at shorter time, i.e. 1 hour in accordance with the GMDSS requirements, it will only be possible to utilize approx. 60% of the battery capacity. It is therefore recommended to dimension such batteries to be one and a half times larger than the total load.

 7.7 Automatic battery chargers

Automatic chargers for radio batteries should meet the general requirements set out in regulation IV/13 of SOLAS 1974, as amended, and IMO resolution A.694(17) and should also comply with the following requirements:

  • .1 The charger should be capable of recharging the completely discharged accumulator batteries to the minimum required capacity within 10 hours.

  • .2 The charger should be capable of keeping the batteries appropriately charged as prescribed by the manufacturer for permanent charging.

  • .3 The supplied voltage and current should always be within the tolerance limits prescribed by the battery manufacturer, taking into account the environmental temperature of the battery, likely to be experienced in ship. A protection should be provided against over charging or discharging of batteries from a possible fault in the charger.

  • .4 The automatic charger should be provided with a visual indication that it is switched on. An indication of the battery voltage and charge/discharge current should be available on the navigation bridge.

  • .5 Provisions should be made for an aural alarm and visual indication at the position from which the ship is normally navigated, indicating when the charging voltage or current is outside the limits given by the manufacturer. It should not be possible to disable this alarm and indication and it should only be possible to acknowledge and silence the alarm manually. Both the alarm condition and indication should reset automatically when normal charging condition has been restored. Failure of the alarm system should not interrupt the charging or discharging of batteries.

  • .6 The automatic charger should be operational within 5 seconds of switching on or after a power supply interruption.

  • .7 The automatic charger should be so designed and constructed that it is protected against damage resulting from disconnection the batteries or, with the battery disconnected, short-circuiting the battery connection. If this protection is provided by electronic means it should automatically reset following removal of the open or short-circuit conditions.

(SOLAS 1974, as amended, regulation IV/13.6.1 and COMSAR/Circ.16)

Note: - As said in subsection 7.1 above, it is not advisable to provide the main source of energy to the GMDSS equipment through the battery charger. However, if the battery charger is used to supply parts of the GMDSS installation directly, i.e. the MF/HF transceiver, the capacity of the charger should be dimensioned for simultaneous supply of connected equipment and maintaining a sufficient charging of the batteries in accordance with SOLAS 1974, as amended, regulation IV/13.2.

 7.8 Protection of circuits for accumulator batteries

  • .1 Battery circuits (i.e. the cables from battery case/room) should be protected against short-circuit and overload. The protection device is to be installed as near as possible to the batteries.

  • .2 When conductors from the batteries are not protected against short-circuit and overload, they are to be installed so as to be proof against short circuit and earth faults. The requirements for short-circuit protection also apply to charge current circuits.

Note: - For certain applications it may be necessary to establish measures which may conflict with these requirements. As an example, screening of battery cables can be required to avoid electro-magnetic interference, e.g. by using single-core insulated cables without screening installed in separate metal pipes which are properly earthed. Special measures should then be established to reduce the possibility of mechanical damage to the cables.

Equivalent solutions may be accepted, e.g. by using double-screened cables in the battery room with explosion-proof fuses. The inner screen should be treated according to Ex-rules, but the outer screen can be treated according to what is necessary to achieve good EMC-screening. The outer screen can e.g. be earthed at both ends to protect against High Frequency EMC-fields.

Parent topic: Annex - Guidelines for the Harmonization of GMDSS Requirements for Radio Installations on Board SOLAS Ships
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