CHAPTER 7 ELECTRICAL EQUIPMENT AND CONTROL SYSTEMS

101. General

1. Electrical equipment and control systems, not mentioned in this chapter, are able to be in accord- ance with the Rules for the Classification of Steel Ships, Pt 6. However, it may be acceptable to the Society that they are satisfied with the requirements in this chapter and the equivalent standard thereto, such as (Federal Aviation Regulation, etc).

2. The System Safety Assessment (SSA) should include the electrical system, taking into account the effects of electrical failure on the system and the possibility of faults occurring simultaneously or consecutively.

3. Where loss of a particular essential service would cause serious risk to the craft, the service should be fed by at least two independent circuits both fed in such a way that no single failure in the electrical supply or distribution system would affect both supplies.

4. The securing arrangements for heavy item such as accumulator batteries, should prevent excessive movement during the accelerations.

5. Precautions should be taken to minimize risk of supplies to essential and emergency services being interrupted by the inadvertent or accidental opening of switches or circuit breakers.

6. Electronic equipment essential for propulsion and altitude control purposes should be approved and installed according to a recognized IEC Standard.

7. Unless otherwise stated in the national or international standards, all equipment are to be operated satisfactorily with the variations from its rated value shown as in the followings.

(1) Voltage and frequency variations for a.c. distribution system

(2) Voltage variations for d.c distribution system

(3) Voltage variations for battery system

Guidance for WIG ships(Wing-In-Ground Effect Ships) 2012 25

8. The total harmonic distortion(THD) in the voltage waveform in the distribution systems is not to exceed 8 % and any single order harmonics not to exceed 3 %.

9. Equipment required to remain operational in an emergency is to be supplied from emergency source of power automatically within 15 seconds in the event of failure of the main supply.

10. Where arrangements are made for the supply of electricity from a source on shore, means are to be provided permanently for checking the phase sequence (for three-phase alternating current) or the polarity (for direct current).

11. Lighting on the craft is to be provided in accordance with the Rules for the Classification of Steel Ships, Pt 6.

12. Sources of power for navigational equipment and radio equipment are to comply with the follow- ing requirements.

(1) All electrical power for navigational equipment and radio equipment is to be supplied from main source of electrical power. In case of failure of the main source of electrical power, it is to be supplied from emergency source of electrical power.

(2) Where installation of the reserve source of electrical power is impracticable, navigational equip-

ment and radio equipment, in case of failure of the main source of electrical power, are to be supplied from accumulator battery used as the emergency source of electrical power. However the accumulator battery is not able to be used as a starter battery.

(3) All electrical power for navigational equipment and radio equipment that require electrical power for their operation is to be supplied by two independent feeders using switch and protection equipment from the switchboard. Electrical power to the switchboard busbars from the main, re- serve or emergency sources, is to be supplied by two independent feeders.

13. Electrical bonding and protection against lightning and static electricity are to comply with the following requirements.

(1) For metallic components, there is to be an electrical bonding to the WIG frame and components are to be designed so that a strike will not endanger the WIG.

(2) For nonmetallic components, they are to be designed so as to minimize the effect of a strike

and acceptable means of diverting the resulting electrical current are to be provided so as not to endager the WIG.

102. Main source of electrical power

1. The main source of electrical power should consist of at least two generating sets (generators or accumulator batteries) and the main switchboards should be located in a dry space to minimize the risk of fire. However, alternative device instead of main switchboard can be used for small WIG or WIG operated by 1 operator.

2. The capacity of these generating sets shall be such that, in the event of any one generating set be- ing stopped or failing, it will still be possible to supply those services necessary to provide the normal operational conditions of propulsion and safety. It shall also be possible to supply services for heating, domestic refrigeration, mechanical ventilation, and sanitary and fresh water.

3. The arrangements of the craft's main source of electrical power should be possible to supply all services regardless of the speed of the propulsion machinery.

4. One source of power independent from the main propulsion plant should be capable of providing the electrical services necessary to start the main propulsion plant.

5. Where charging units or converters constitute an essential part of the electrical supply system, the system should be so arranged as to ensure the same continuity of supply.

6. A main electric lighting system, which should provide illumination throughout those parts of the craft normally accessible to and used by passengers and crew should be supplied from the main source of electrical power.

7. The connection of generating sets and any other duplicated equipment should be equally divided between the two switchboards. The generators should operate in single operation. Equivalent ar- rangements may be permitted to the satisfaction of the Society.

8. The main source of electrical power system should be able to provide normal operation of pro-

26 Guidance for WIG ships(Wing-In-Ground Effect Ships) 2012

pulsion engine at any load. Automatic load-dependent disconnection of non-essential consumers may be allowed.

103. Emergency source of electrical power

1. A self-contained emergency source of electrical power should be provided.

2. The emergency source of electrical power, any associated transforming equipment, transitional source of electrical power, emergency switchboard and emergency lighting switchboard should be located above the waterline in the final condition of damage as referred to in Ch 5, operable in that con- dition and readily accessible.

3. The location of the emergency source of electrical source and any associated transforming equip- ment, the transitional source of emergency power, the emergency switchboard and the emergency lighting switchboards should be such as to ensure that a fire or other casualty in spaces containing the main source of electrical power, any associated transforming equipment and main switchboard will not interfere with the supply, control and distribution of emergency electrical power.

4. Distribution system should be so arranged that the feeders from the main and emergency sources be separated both vertically and horizontally as widely as practicable.

5. The emergency source of electrical power should be automatically connected the emergency switch- board in the event of failure of the main source of electrical power and the electrical power should be supplied to equipment as referred to in 11. It also may be either a generator or an accumulator battery, which shall comply with the following:

(1) Where the emergency source of electrical power is a generator, it should be driven by a suit- able prime mover with an independent supply of fuel having a flash point which meets the reg- ulations and be provided with a transitional source of emergency electrical power according to the below 12.

(2) Where the emergency source of electrical power is an accumulator battery, it should be capable of carrying the emergency electrical load without recharging while maintaining the voltage of the battery throughout the discharge period within 12 % above or below its nominal voltage.

6. Where accumulator batteries are used as emergency source of power, an indicator should be mount- ed in a suitable space at the WIG's operating compartment to indicate discharges.

7. The emergency switchboard should be supplied during normal operation from one main switchboard by an interconnection feeder which should be adequately protected at the main switchboard against overload and short circuit and which should be disconnected automatically at the emergency switch- board upon failure of the main source of electrical power.

8. Only emergency circuits should be fed by the emergency switchboard.

9. The emergency generator and its prime mover and any emergency accumulator battery should be so designed and arranged as to ensure that they will function at full rated power when WIG is up- right and when WIG has a list or trimming because of WIG's damage.

10. Where accumulator batteries are installed to supply emergency, back up or engine start-up serv- ices, provisions should be made to charge them from a reliable on-board supply. Charging facilities should be designed to permit the supply of services, regardless of whether battery is on charge or not. Means should be provided, by which the batteries on board can be checked before each jour- ney(e.g. minimum allowable voltage at a laid down load). The risk of overcharging or overheating the batteries should be minimized. Means for efficient air ventilation should be provided.

11. The emergency source of power should be capable of supplying simultaneously the following serv- ices:

(1) for a period of 5 hours about the following emergency lighting

(A) at the stowage positions of life-saving appliances

(B) at all escape routes, such as alleyways, stairways, exit from spaces, embarkation points etc.

(C) in the public spaces

(D) in the machinery spaces and main emergency generating spaces, tions

(E) in control stations

accommodation and service including their control posi-

Guidance for WIG ships(Wing-In-Ground Effect Ships) 2012 27

(F) at the stowage positions for any firemen's outfits fitted

(2) for a period of 5 hours about the following equipment

(A) main navigation lights, except for "not under command" lights

(B) electrical internal communication equipment for announcements for passengers and crew re- quired during evacuation

(C) fire-detection and general alarm system and manual fire alarms

(D) remote control devices of fire-extinguishing systems, if electrical

(3) for a period of 4 hours of intermittent operation about the following equipment

(A) the daylight signalling lamps, if they have no independent supply from their own accumu-

lator battery

(B) the craft's whistle, if electrically driven

(4) for a period of 5 hours about the following equipment

(A) craft radio facilities and their other facilities

(B) essential electrically powered instruments and controls for propulsion machinery, if alternate sources of power are not available for such devices

(5) for a period of 12 hours about "not under command" lights

(6) for a period of 10 minutes about power drives for directional control devices, including those required to direct thrust forward and astern, unless there is a manual alternative acceptable to the Society.

12. The transitional source of emergency electrical power is the battery suitably located for use in an emergency which should operate without recharging while maintaining the voltage of the battery throughout the discharge period within 12 % above or below its normal voltage and be of sufficient capacity and so arranged as to supply automatically in the event failure of either the main and emergency source of electrical power at least the following services, if they depend upon an elec- trical source for their operation for a period of 30 minutes, the load specified in 11 (1) to 11 (3).

13. The above provision, 12 may be considered satisfied without the installation of a transitional source of emergency electrical power if each of the services have independent supplies, for the pe- riod specified, from accumulator batteries suitably located for use in an emergency. The supply of emergency power to the instruments and controls of the propulsion and direction systems should be uninterruptible.

14. Distribution systems should be so arranged that fire in any main vertical zone will not interfere with services essential for safety in any other such zone. This requirement will be met if main and emergency feeders passing through any such zone are separated both vertically and horizontally as widely as practicable.

104. Starting arrangements for generating sets

1. aTthueregeonfer0a℃tin.g Isfettshisshoius ldimbperaccatpicaabblele,ofobreinf glowreeardiltyemsptearratetudresin arteheliirkeclyoldto cboendeitnioconunatteread, tepmropveir-- sions should be made for heating arrangements to ensure ready starting of the generating sets.

The main generating set(emergency generator set) should be equipped with starting devices with a

2. stored energy capability of at least six(three) consecutive starts. The source of stored energy should

be protected to preclude critical depletion by the automatic starting system. A second source of en- ergy should also be provided for an additional six(three) starts. However, the installation of the sec- ond source of energy is not necessary in case a bundle of propulsion engines are installed.

The stored energy of the emergency generating set should be maintained at all times and comply

3. with the followings:

(1) Electrical and hydraulic starting systems should be maintained from the emergency switchboard.

(2) Compressed air starting systems may be maintained by the main or auxiliary compressed air re- ceivers through a suitable non-return valve or by an emergency air compressor which, if electri- cally driven, is supplied from the emergency switchboard.

(3) All of these starting, charging and energy storing devices should be located in the emergency

generator space. These devices should not be used for any purpose other than the operation of the emergency generating set. This does not preclude the supply to the air receiver of the emer- gency generating set from the main or auxiliary compressed air system through the non-return valve fitted in the emergency generator space.

28 Guidance for WIG ships(Wing-In-Ground Effect Ships) 2012

105. Steering and attitude control

1. Where

ability

steering and/or altitude control of a craft is essentially dependent on the continuous avail- of electric power, it should be served by at least two independent circuits, one of which

should be fed from the main switchboards and one from the emergency source of electric power including the transitional source, both located in such a position as to be unaffected by fire or

flooding affecting the main source of power. Failure of either supply should not cause any risk to the craft or passengers during switching to the alternative supply. These circuits should be provided with short circuit protection and an overload alarm. Where steering and/or altitude control of a craft

is not essentially dependent on the continuous availability of electric power, it is to comply with fail- safe conditions including mechanical or hydraulic methods in the event of power failure.

2. Protection against excess current may be provided, in which case it should be for not less than twice the full load current of the motor or circuit so protected, where three-phase supply is used, an alarm should be provided in a readily observed position in the craft's operating compartment that will indicate failure in any one of the phases.

3. Where such systems are not essentially dependent on the continuous availability of electric power but at least one alternative system, not dependent on the electric supply, is installed, then the elec- trically powered or controlled system may be fed by a single circuit protected in accordance with the above 3.

4. The provisions of Ch 11, 102. for power supply of the directional control systems and stabilization systems of the craft should be met.

106. Precautions against shock, fire and other hazards of electrical origin

1. Exposed metal parts of electrical machines or equipment which are not intended to be live but which are liable under fault conditions to become live should be earthed unless the machines or equipment are :

(1) supplied at a voltage not exceeding 55V d.c. or 55V a.c. root-mean-square between conductors, auto-transformers should not be used for the purpose of achieving this voltage : or

(2) supplied at a voltage not exceeding 250V by safety isolating transformers supplying only one

consuming device ; or

(3) constructed in accordance with the principle of double insulation.

2. All electrical apparatus should be so constructed and so installed as not to cause injury when han- dled or touched in the normal manner.

3. Main and emergency switchboards should be so arranged as to give easy access, as may be need- ed, to apparatus and equipment, without danger to personnel. The sides and the rear and, where necessary, the front of switchboards should be suitably guarded. Dead-front type switchboards are to be installed for voltage between poles, or to earth, exceeding 55V d.c. or 55V a.c. Where neces- sary, nonconducting mats or gratings should be provided at the front and rear of the switchboard.

4. When a distribution system, whether primary or secondary, for power, heating or lighting, with no connection to earth is used, a device capable of continuously monitoring the insulation level to earth and of giving an audible and visual indication of abnormally low insulation values should be provided. For limited secondary distribution systems, the Society may accept a device for manual checking of the insulation level as long as the performance and safety are proved.

5. Cables and wiring

(1) Power cables and control or communication cables as well as cables of each main supply and emergency supply should be installed on separated cable runs. Power and control cables for emergency consumers should be fire-resistant when they pass through fire risk areas. Where, for safety reasons, a system has duplicated supply and/or control cables, the cable routes should be placed as far apart as possible.

(2) All metal sheaths and armour of cables should be electrically continuous and should be earthed.

(3) All electric cables and wiring external to equipment should be at least of a halogen-free flame- retardant type and should be so installed as not to impair their original flame-retarding properties. Where necessary for particular applications, the Society may permit the use of special types of cables such as radio frequency cables as long as there is nothing wrong about safety.

(4) Cables and wiring serving essential or emergency power, lighting, internal communications or

Guidance for WIG ships(Wing-In-Ground Effect Ships) 2012 29

signals should, so far as practicable, be routed clear of machinery spaces and their casing and other high fire risk areas. Where practicable, all such cables should be run in such a manner as to preclude their being rendered unserviceable by heating of the bulkheads that may be caused by a fire in an adjacent space.

(5) Where cables which are installed in hazardous areas introduce the risk of fire or explosion in the event of an electrical fault in such areas, special precautions against such risks should be taken to the satisfaction of the Society.

(6) Cables and wiring should be installed and supported in such manner as to avoid chafing or oth- er damage.

(7) Terminations and joints in all conductors should be so made as to retain the original electrical,

mechanical, flame-retarding and, where necessary, fire-resisting properties of the cable.

6. Each separate circuit should be protected against short circuit and against overload, except as per- mitted in section 105. or where the Society may exceptionally otherwise permit because safety is proved. For supplies with 400 cycles, the impedance of the circuits should be observed.

7. When the protective device is a fuse, it should be placed on the load side of the disconnect switch serving the protected circuit.

8. Lighting fittings should be so arranged as to prevent temperature rises which could damage the ca- bles and wiring, and to prevent surrounding material from becoming excessively hot.

9. Accumulator batteries should be suitably housed, and compartments used primarily for their accom- modation should be properly constructed and efficiently ventilated.

10. Electrical or other equipment, which may constitute a source of ignition of flammable vapours, should not be permitted in compartments likely to contain such vapours.

11. The following additional provisions from (1) to (9) should be met, and provisions from (10) to

(15) should be met also for nonmetallic craft:

(1) The electrical distribution voltages throughout the craft may be either direct current or alternat- ing current and should not exceed:

(A) 500 V for power, cooking, heating, and other permanently connected equipment, and

(B) 250 V for lighting, internal communications and receptacle outlets.

(2) For electrical power distribution, earthed system with non hull-return are acceptable.

(3) Earthed electrical distribution system should not be used, with the exception of earthed intrinsi- cally safe circuits.

(4) Suitable certified safe type electrical equipment should be used in all spaces where fuel leakage could occur, including the ventilation system. Only electrical equipment and fittings essential for operational purposes be fitted in such spaces.

(5) Effective means should be provided so that voltage may be cut off from each and every circuit and subcircuit and from all apparatus as may be necessary to prevent danger.

(6) Electrical equipment should be so designed that the possibility of accidentally touching live

parts, rotating or moving parts as well as heated surfaces which might cause burns or initiate fire is minimized.

(7) Electrical equipment should be adequately secured. The probability of fire or dangerous con- sequences arising from damage to electrical equipment should be reduced to an acceptable

minimum.

(8) The rating or appropriate setting of the overload protective device for each circuit should be permanently indicated at the location of the protection device.

(9) Where it is impracticable to provide electrical protective devices for certain cables supplied from

batteries, e.g. within battery compartments and in engine starting circuits, unprotected cable runs should be kept as short as possible and special precautions should be taken to minimize risk of faults, e.g. use of single core cables with additional sleeve over the insulation of each core, with shrouded terminals.

(10) In order to minimize the risk of fire, structural damage, electrical shock and radio interference due to lightning strike or electrostatic discharge, all metal parts of the craft should be bonded

together, in so far as possible in consideration of galvanic corrosion between dissimilar metals,

to form a continuous electrical system, suitable for the earth return of electrical equipment and to connect the craft to the water when waterborne. The bonding of isolated components inside the structure is not generally necessary, except in fuel tanks.

(11) Each refueling point should be provided with a means of bonding the fuelling equipment to

the craft.

30 Guidance for WIG ships(Wing-In-Ground Effect Ships) 2012

(12) Metallic pipes capable of generating electrostatic discharges, due to the flow of liquids and gases, should be bonded so as to be electrically continuous throughout their length and should be adequately earthed.

(13) Primary conductors provided for lightning discharge currents should have a minimum cross section of 50 mmĪ in copper or equivalent surge carrying capacity in aluminium.

(14) Secondary conductors provided for the equalization of static discharges, bonding of equipment, etc., but not for carrying lightning discharges should have a minimum cross section of 5 mm Ī

copper or equivalent surge

(15) The electrical resistance

0.05 Ohm, except where hazard. The bonding path

current carrying capacity in aluminium.

between bonded objects and the basic structure should not exceed it can be demonstrated that a higher resistance will not cause a

should have sufficient cross-sectional area to carry the maximum cur-

rent likely to be imposed on it without excessive voltage drop.

Guidance for WIG ships(Wing-In-Ground Effect Ships) 2012 31