IEC 61892-5:2000
(Main)Mobile and fixed offshore units - Electrical Installations - Part 5: Mobile units
Mobile and fixed offshore units - Electrical Installations - Part 5: Mobile units
This part of IEC 61892 specifies the characteristics for electrical installations in floating units,for use during transfer from one location to another and for use during the exploration and exploitation of petroleum resources. The requirements specified in this International Standard are based on the Code for the Construction and Equipment of Mobile Offshore Drilling Units (1989 MODU CODE) published by the International Maritime Organization (IMO), and might include additional provisions. This part of IEC 61892 supersedes IEC publication 60092-505, third edition (1984) and its amendment 1 (1993).
General Information
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Standards Content (Sample)
INTERNATIONAL IEC
STANDARD
61892-5
First edition
2000-08
Mobile and fixed offshore units –
Electrical installations –
Part 5:
Mobile units
Unités mobiles et fixes en mer –
Installations électriques –
Partie 5:
Unités mobiles
Reference number
Numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series.
Consolidated publications
Consolidated versions of some IEC publications including amendments are
available. For example, edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the
base publication, the base publication incorporating amendment 1 and the base
publication incorporating amendments 1 and 2.
Validity of this publication
The technical content of IEC publications is kept under constant review by the IEC,
thus ensuring that the content reflects current technology.
Information relating to the date of the reconfirmation of the publication is available
in the IEC catalogue.
Information on the subjects under consideration and work in progress undertaken
by the technical committee which has prepared this publication, as well as the list
of publications issued, is to be found at the following IEC sources:
• IEC web site*
•
Catalogue of IEC publications
Published yearly with regular updates
(On-line catalogue)*
• IEC Bulletin
Available both at the IEC web site* and as a printed periodical
Terminology, graphical and letter symbols
For general terminology, readers are referred to IEC 60050: International
Electrotechnical Vocabulary (IEV).
For graphical symbols, and letter symbols and signs approved by the IEC for
general use, readers are referred to publications IEC 60027: Letter symbols to be
used in electrical technology, IEC 60417: Graphical symbols for use on equipment.
Index, survey and compilation of the single sheets and IEC 60617: Graphical symbols
for diagrams.
* See web site address on title page.
INTERNATIONAL IEC
STANDARD
61892-5
First edition
2000-08
Mobile and fixed offshore units –
Electrical installations –
Part 5:
Mobile units
Unités mobiles et fixes en mer –
Installations électriques –
Partie 5:
Unités mobiles
IEC 2000 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
Commission Electrotechnique Internationale
PRICE CODE
U
International Electrotechnical Commission
For price, see current catalogue
– 2 – 61892-5 © IEC:2000(E)
CONTENTS
Page
FOREWORD . 3
INTRODUCTION .5
Clause
1 Scope . 6
2 Normative references . 6
3 Definitions. 7
4 General requirements. 8
5 Limits of inclination of the unit . 9
6 Bilge pumps . 9
7 Navigation lights. 10
8 Steering gear . 10
9 Electric propulsion. 13
10 Dynamic positioning . 22
11 Ballast systems . 22
12 Jacking systems. 24
13 Anchoring systems . 26
Bibliography . 28
61892-5 © IEC:2000(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MOBILE AND FIXED OFFSHORE UNITS –
ELECTRICAL INSTALLATIONS –
Part 5: Mobile units
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61892-5 has been prepared by IEC technical committee 18:
Electrical installations of ships and of mobile and fixed offshore units.
The text of this standard is based on the following documents:
FDIS Report on voting
18/885/FDIS 18/886/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
Upon authorization by national maritime administrations, classification societies carry out
statutory work on their behalf. Relevant rules of a classification society need to be approved by
the national maritime administration, and may differ worldwide
The requirements specified in this International Standard are based on the Code for the
Construction and Equipment of Mobile Offshore Drilling Units (1989 MODU CODE) published
by the International Maritime Organization (IMO), and might include additional provisions.
This part of IEC 61892 supersedes IEC publication 60092-505, third edition (1984) and its
amendment 1 (1993).
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
A bilingual version of this standard may be issued at a later date.
– 4 – 61892-5 © IEC:2000(E)
IEC 61892 consists of the following parts, under the general title: Mobile and fixed offshore
units – Electrical installations:
Part 1: General requirements and conditions
Part 2: System design
Part 3: Equipment
Part 4: Cables
Part 5: Mobile units
Part 6: Installation
Part 7: Hazardous areas
The committee has decided that the contents of this publication will remain unchanged
until 2005-12. At this date, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
61892-5 © IEC:2000(E) – 5 –
INTRODUCTION
IEC 61892 forms a series of International Standards intended to ensure safety in the design,
selection, installation, maintenance and use of electrical equipment for the generation, storage,
distribution and utilization of electrical energy for all purposes in offshore units used for
exploration or exploitation of petroleum resources.
This standard is based on equipment and practices which are in current use, but it is not
intended in any way to impede development of new or improved techniques.
The ultimate aim has been to produce a set of International Standards exclusively for the
offshore petroleum industry.
In this part of IEC 61892, reference is made to other parts of the standard, which are still in
preparation. Footnotes are attached to such references. A footnote indicates which current
standard should be used until the part in preparation is published.
– 6 – 61892-5 © IEC:2000(E)
MOBILE AND FIXED OFFSHORE UNITS –
ELECTRICAL INSTALLATIONS –
Part 5: Mobile units
1 Scope
This part of IEC 61892 specifies the characteristics for electrical installations in floating units,
for use during transfer from one location to another and for use during the exploration and
exploitation of petroleum resources.
NOTE Attention is drawn to further requirements concerning electrical installations on such mobile offshore units
contained in the MODU CODE of the International Maritime Organization (IMO).
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61892. For dated references, subsequent amendments
to, or revisions of, any of these publications do not apply. However, parties to agreements
based on this part of IEC 61892 are encouraged to investigate the possibility of applying the
most recent editions of the normative documents indicated below. For undated references, the
latest edition of the normative document referred to applies. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 60034-1:1996, Rotating electrical machines – Part 1: Rating and performance
IEC 60034-6:1991, Rotating electrical machines – Part 6: Methods of cooling (IC Code)
IEC 60092-201, Electrical installations in ships – Part 201: System design – General
IEC 60092-401:1980, Electrical installations in ships − Part 401: Installation and test of
completed installation
Amendment 1 (1987)
Amendment 2 (1997)
IEC 60332-1:1993, Tests on electric cables under fire conditions – Part 1: Test on a single
vertical insulated wire or cable
IEC 61892-3:1999, Mobile and fixed offshore units – Electrical installations – Part 3:
Equipment
IEC 61892-6:1999, Mobile and fixed offshore units – Electrical installations – Part 6: Installation
IMO Guidelines for vessels with dynamic positioning systems – see IMO/Circ. 645, Annex,
International Maritime Organization
IMO 904E, Convention on the International Regulations for Preventing Collisions at Sea,
International Maritime Organization
________
61892-5 © IEC:2000(E) – 7 –
3 Definitions
For the purposes of this part of IEC 61892, the following definitions apply.
3.1
auxiliary steering gear
equipment, other than any part of the main steering gear, necessary to steer the unit in the
event of failure of the main steering gear but not including the tiller, quadrant or components
serving the same purpose
3.2
dynamic positioning (DP) system
equipment necessary to provide means of controlling the position and heading of a mobile unit
within predetermined limits by means of resultant vectored thrust
3.3
electrical coupling
coupling in which the torque is transmitted by the interaction of the magnetic field produced by
magnetic poles on one rotating member and induced current in the other rotating member
NOTE 1 The magnetic field may be produced by direct current excitation, permanent magnet excitation, or
alternating current excitation. The induced current may be carried in a cage or insulated winding or may be present
as eddy current.
NOTE 2 Couplings utilizing a wound secondary winding or a cage winding are known as slip or magnetic
couplings. Couplings utilizing eddy-current effects are known as eddy-current couplings.
3.4
electric steering gear
power operated steering gear where an electric motor applies torque to the rudder stock
through mechanical means only
3.5
electrohydraulic steering gear
power operated steering gear where a hydraulic pump, driven by an electric motor, applies
torque to the rudder stock through hydraulic and mechanical means
3.6
main steering gear
machinery, rudder actuators, steering gear power units and ancillary equipment and the means
of applying torque to the rudder stock (for example tiller or quadrant) necessary for effecting
movement of the rudder for the purpose of steering the unit under normal service conditions
3.7
petroleum
complex mixture of hydrocarbons that occurs in the earth in liquid, gaseous or solid forms
3.8
propulsion machine (electric)
rotating machine normally intended to provide propulsive power
3.9
redundancy
in an item, the existence of more than one means for performing a required function
– 8 – 61892-5 © IEC:2000(E)
3.10
semiconductor convertor
static device using semiconducting elements to convert electric energy from one state to
another
3.11
steering gear control system
equipment by which orders are transmitted from the navigating bridge to the steering gear
power units
NOTE Steering gear control systems comprise transmitters, receivers, hydraulic control pumps and their
associated motors, motor controllers, piping and cables, etc.
3.12
steering gear power unit (electric steering gear��
electric motor and its associated electrical equipment used to operate the steering gear
3.13
steering gear power unit (electrohydraulic steering gear)
electric motor and its associated electrical equipment and connected pump used to operate the
steering gear
4 General requirements
4.1 In every mobile unit in which electric power is used for the services necessary for the
safety of the unit, the generators, switchgear, motors and associated controlgear for such
services, with the exception of machinery in the platform of semi-submersibles, shall be so
situated or arranged that they continue to operate satisfactorily in the event of partial flooding
by bilge water above the tank top in the space in which they are situated. The design criterion
th
for partial flooding shall be assumed to be a depth of water 1/12 beam but not exceeding a
depth of 1,5 m except where this requirement is impracticable for horizontally mounted
propulsion generators and motors. In such circumstances the machine enclosures shall, at
least, be watertight to the underside of the shaft.
4.2 Rotating machines shall be installed to minimise the effects of motion. The design of
bearings of all machines and the arrangement for their lubrication shall be adequate to
withstand the motions encountered in heavy weather and operation for prolonged periods at the
list and trim specified in clause 5 without the spillage of oil.
4.3 Conductors and equipment shall be placed at such a distance from each magnetic
compass or shall be so disposed that the interfering external magnetic field is negligible; that
is, the total singular deviation shall not exceed 30 minutes when any combination of circuits is
switched on and off.
4.4 Where the total installed electrical power of the main generators exceeds 3 MW the
busbars of the main switchboard shall be subdivided into at least two parts. The subdivision
may be effected by removable links, circuit-breakers or other suitable means so that the main
generators and any supplies to duplicated services which are directly connected to the busbars
are, as far as is practicable, equally divided between the sections.
61892-5 © IEC:2000(E) – 9 –
5 Limits of inclination of the unit
5.1 Dependent upon the outcome of all studies relevant to the intact and damaged stability of
the unit, the appropriate authority may require or permit deviations from the angles stated in
5.2, 5.3 and 5.4.
5.2 All machines and apparatus shall operate satisfactorily under all conditions with the unit
upright and when inclined up to the following angles from the normal:
− for column stabilized units, 15° in any direction;
− for self-elevating units, 10° in any direction;
− for surface units, 15° either way in list and simultaneously trimmed 5° by the bow or stern.
5.3 Main propulsion machinery and all auxiliary machinery essential to the propulsion and
safety of the mobile unit shall be capable of operating under the static conditions specified in
5.2 and the following dynamic conditions:
– for column stabilized units, 22° 30′ in any direction;
– for self-elevating units, 15° in any direction;
– for surface units, 22° 30′ rolling and simultaneously pitching 7° 30′ by the bow or stern.
Emergency machines and apparatus fitted in accordance with requirements from the
5.4
appropriate authority for emergency plant shall operate satisfactorily under all conditions with
the unit upright and when inclined up to the following maximum angles from the normal:
– for column stabilized units, 25° in any direction;
– for self-elevating units, 15° in any direction;
– for surface units, 22° 30′ about the longitudinal axis and/or when inclined 10° about the
transverse axis.
5.5 Where required by the appropriate authority, dynamic condition limits shall apply as
follows:
– rotation about fore-and-aft axis (rolling), ±22° 30′
– rotation about athwartship (pitching), ±7° 30′
NOTE These motions may occur simultaneously.
6 Bilge pumps
6.1 Motors of permanently installed emergency bilge pumps, if any, shall be connected to an
emergency switchboard.
6.2 Cables and their connections to submersible pumps shall be capable of operating under a
head of water equal to their distance below the worst damaged condition waterline. The cables
shall either be armoured or mechanically protected by other means and shall not be installed
within the assumed extent of damage. They shall be installed in continuous lengths from above
the worst damaged condition waterline to the motor terminals, entering the air-bell from its
underside.
6.3 Under all circumstances it shall be possible to start the motor of a permanently installed
bilge pump from a convenient point above the worst damaged condition waterline and in a
space not within the assumed extent of damage.
NOTE The worst damaged condition waterline and the spaces within the assumed extent of damage shall be in
accordance with IMO requirements.
– 10 – 61892-5 © IEC:2000(E)
7 Navigation lights
7.1 Except when a unit is stationary and engaged in operations, attention is drawn to IMO
904E, the Convention on the International Regulations for Preventing Collisions at Sea.
7.2 When a unit is stationary and engaged in operations, attention is drawn to the
requirements for the safety of navigation of the coastal state in whose territorial sea or on
whose continental shelf the unit is operating.
7.3 All units shall be provided with "steaming lights" which comprise masthead, side, stern,
anchor, not-under-command and, if applicable, special-purpose lights. The construction and
installation of navigation lights shall be to the satisfaction of the appropriate authority.
7.4 Attention is drawn to the Collision Regulations in relation to the provision of primary and
alternative lanterns for each of the navigation lights.
7.5 The following electrical arrangements relate only to the navigation lights referred to in 7.3
and 7.4.
– Each light shall be connected by a separate cable to a distribution board reserved solely for
navigation lights, fitted in an accessible place under the control of watchkeeping personnel.
– There shall be two separate power supply systems to the distribution board, one being from
the main switchboard and one from the emergency switchboard. Where a transitional
source of emergency power is required by the Safety of Life at Sea (SOLAS) Convention,
the arrangements shall enable the lights to be supplied from this source in addition to the
emergency switchboard.
– So far as is practicable, the arrangements should be such that a fire, a fault or mechanical
damage at any one point will not render both systems inoperative. It is, however, accepted
that the systems must come together at some point where the changeover can be effected.
This should, preferably, be at or near to the distribution board.
– Each light shall be controlled and protected in each insulated pole by a switch and fuse or
by a circuit-breaker mounted in the distribution board.
– Each light shall be provided with an automatic indicator to give an acoustic and/or optical
alarm in the event of a lamp failure. If an optical signal is used, which is connected in
series with the steaming light, means to prevent failure of the indicator extinguishing the
steaming light shall be provided. If an acoustic device alone is used it shall be connected to
an independent source of supply, for example a battery, and provision shall be made for
testing this supply.
8 Steering gear
8.1 Power operated steering gear
8.1.1 Electric and/or electrohydraulic steering gear shall be used for the power-operated main
and auxiliary steering gear required by the appropriate authorities.
8.1.2 The electrical systems of the main steering gear and auxiliary steering gear shall be so
arranged that any failure in one of the steering gears will not render inoperative the electrical
systems of the other steering gear.
When an auxiliary steering gear is not required by the appropriate authorities and the main
steering gear comprises two or more power units, the electrical system for each power unit
shall be so arranged that the failure of one of them will not render the other units inoperative.
61892-5 © IEC:2000(E) – 11 –
8.2 Motors
8.2.1 To determine the required characteristics of the electric motors for power units, the
breakaway torque and maximum working torque of the steering gear under all operating
conditions shall be used. The ratio of pull-out torque to rated torque shall be at least 1,6.
8.2.2 The rating shall be determined on the basis of the steering gear characteristics of the
subject unit as specified in 8.2.2.1 and 8.2.2.2.
NOTE Motors for steering gear power units may be rated for intermittent power demand.
8.2.2.1 For motors of electric steering gear power units the rating shall be as follows:
S3 – 40 % in accordance with lEC 60034-1.
8.2.2.2 For motors of electrohydraulic steering gear power units and for convertors the rating
shall be as follows:
S6 – 25 % in accordance with IEC 60034-1.
8.3 Motor starters
Each electric motor of a main or auxiliary steering gear power unit shall be provided with its
own separate motor starter gear either located within the steering gear compartment or in the
supply switchboard rooms (see 8.1.2).
8.4 Power circuits supply
8.4.1 Each electric or electrohydraulic steering gear comprising one or more power units
should, except as otherwise permitted by the appropriate authorities, be served by at least two
exclusive circuits, one fed directly from the main switchboard and one of the circuits shall be
supplied through the emergency switchboard.
NOTE An auxiliary electric or electrohydraulic steering gear associated with a main electric or electrohydraulic
steering gear may be connected to one of the circuits supplying the main steering gear.
8.4.2 The circuits supplying an electric or electrohydraulic steering gear shall have a
continuous rating for supplying all electric motors and devices which can be simultaneously
connected to them and may be required to operate simultaneously.
8.4.3 For certain units specified by the appropriate authorities, an alternative power supply
from the emergency source of electrical power or from an independent source of power located
within the steering gear compartment, is required.
This power supply shall be activated automatically, within 45 s, in the event of power failure of
the main source(s) of electrical power and shall meet the requirements of the appropriate
authorities.
8.5 Supply of control circuits and control systems
8.5.1 Each control for starting and stopping of motors for power units shall be served by its
own control circuit supplied from its respective power circuit.
8.5.2 Any electrical main and auxiliary steering gear control system shall be served by its own
separate circuit supplied from a steering gear power circuit from a point within the steering
gear compartment, or directly from switchboard busbars supplying that steering gear power
circuit at a point on the switchboard adjacent to the supply to the steering gear power circuit.
– 12 – 61892-5 © IEC:2000(E)
8.6 Circuit protection
8.6.1 Short-circuit protection shall be provided for each control circuit and each power circuit
of electric or electrohydraulic main and auxiliary steering gear.
8.6.2 No protection other than short-circuit protection shall be provided for steering gear
control system supply circuits.
8.6.3 Protection against excess current, if provided for power circuits, shall be for not less
than twice the full load current of the motor or circuit so protected, and shall be arranged to
permit the passage of the appropriate starting currents.
8.7 Starting and stopping of motors for steering gear power units
8.7.1 Motors for power units shall be capable of being started and stopped from a position on
the navigating bridge and from a point within the steering gear compartment.
Means shall be provided at the position of the motor starters for isolating any remote controlled
starting and stopping devices.
8.7.2 Main and auxiliary steering gear power units shall be arranged to restart automatically
when power is restored after a power failure.
8.8 Steering gear control systems
8.8.1 For the main steering gear, control for the steering gear shall be provided both on the
navigating bridge and in the steering gear compartment.
8.8.2 For the power operated auxiliary steering gear, control for steering gear shall be
provided in the steering gear compartment and it shall also be operable from the navigating
bridge and shall be independent of the control system for the main steering gear.
8.8.3 When, in accordance with the appropriate authorities, an auxiliary steering gear is not
installed and the main steering gear comprises two or more identical power units, two
independent control systems shall be provided, both operable from the navigating bridge and
the steering gear compartment.
NOTE This does not require duplication of the steering wheel or steering lever.
Where the control system includes a hydraulic telemotor, a second independent control system
need not be fitted, except where specified by the appropriate authorities.
8.8.4 The steering gear control system provided in accordance with 8.8.1, 8.8.2 and 8.8.3
shall be capable of being brought into operation from a position on the navigating bridge.
8.8.5 Means shall be provided in the steering gear compartment for isolating any steering
gear control system operable from the navigating bridge from the steering gear it serves.
8.9 Alarms and indications
8.9.1 Means for indicating that the motors of electric and electrohydraulic steering gear are
running shall be installed on the navigating bridge and at a suitable main machinery control
position.
8.9.2 Overload alarms shall be provided for motors of power units for all main and auxiliary
steering gear.
61892-5 © IEC:2000(E) – 13 –
8.9.3 Where a three-phase power supply is used, an alarm shall be provided that will indicate
failure of any one of the supply phases.
8.9.4 In the event of a power failure to any one of the steering gear power units, an alarm
shall be given.
8.9.5 In the event of a power failure of electrical power supply to the control system, an alarm
shall be given.
8.9.6 A low level alarm for each hydraulic fluid reservoir shall be provided to give the earliest
practicable indication of hydraulic fluid leakage.
8.9.7 The alarms specified in 8.9.2 to 8.9.6 shall be both audible and visual and should be located
as indicated in 8.9.1 and as specified by the appropriate authorities.
8.10 Rudder angle indication
The angular position of the rudder shall be indicated on the navigating bridge. The rudder angle
indication system shall be independent of the steering gear power and control systems and be
supplied either through the emergency switchboard or by an alternative independent source of
electric power.
NOTE The angular position of the rudder should be recognizable, in accordance with the appropriate authorities, in
the steering gear compartment. The indication need not be electrical.
8.11 Separation of circuits
Duplicated electric power circuits and their steering gear control systems with their associated
components should be separated as far as practicable.
The corresponding cables should follow different routes, which should be separated both
vertically and horizontally, as far as practicable, throughout their entire length.
8.12 Communication between navigating bridge and steering gear compartment
A means of communication shall be provided between the navigating bridge and the steering
gear compartment.
If electrical, it shall be fed through the emergency switchboard; if not, it shall be sound-
powered.
9 Electric propulsion
9.1 General
Clause 9 is applicable to electric propulsion machinery and plants and deals with propulsion
motors, propulsion generators and their prime movers, electrical couplings, excitation systems,
semiconductor convertors, control monitoring, instrumentation and protection equipment and
systems and wires and cables.
NOTE 1 Requirements applicable to propulsion systems may also be applicable to other consumers directly
connected to the main electric propulsion system, the functioning of which may influence the propulsion or
manoeuvrability of the unit.
NOTE 2 For semiconductor convertors, reference is made to IEC 61892-3 and IEC 61892-6
– 14 – 61892-5 © IEC:2000(E)
9.2 General requirements
9.2.1 Torque and critical speeds
9.2.1.1 The normal torque available in the propulsion motors for manoeuvring shall be such
as to enable the unit to be stopped or reversed, when the unit is travelling at its maximum
service speed, in a time to be agreed between the builder and the manufacturers of the
electrical propulsion equipment. This time shall be based on the estimated torque-speed
characteristics of the propeller during manoeuvring and on other necessary characteristics
supplied to the manufacturers of the electrical systems.
NOTE This subclause contains requirements that have to be agreed between manufacturer and purchaser.
9.2.1.2 Adequate torque margin shall be provided in a.c. propulsion systems to guard against
the motor pulling out of synchronism during rough weather, and on a multiple screw unit when
turning, based on the information provided regarding propeller and unit characteristics.
9.2.1.3 In order to prevent excessive torsional stresses and torsional vibrations of excessive
magnitude, careful consideration shall be given to co-ordination of the mass constants and the
elasticity constants of the entire propulsion system, and electrical characteristics in the system.
9.2.1.4 The entire system, inter alia, includes prime movers, generators, convertors, exciters,
motors, slip couplings, gearing, shafting and propeller.
9.2.1.5 The electrical system shall be stable under all operating conditions, due regard being
paid to switching transients, system recovery after fault and/or maloperation. Operation of the
protection equipment shall also be reviewed under these conditions.
NOTE 1 Where generating sets also supply power to services other than propulsion, consideration should be given
to the starting requirements of a.c. propulsion machines, such that this should be achieved within the limits of
voltage and frequency transient values.
NOTE 2 Where generating sets also supply power to services other than propulsion, consideration should be paid
to the priority of the consumers. Power management systems should be taken into consideration.
9.2.2 Lubrication
The lubrication of the bearings of propulsion motors, gearing and shafting shall be effective at
all normal speeds from creep speeds upwards either ahead or astern.
The shafts and bearings shall not be damaged by slow rotation, whether or not electrical power
is applied to the motor or whether or not such rotation is induced by the propeller, and under all
predictable oil temperature conditions.
NOTE Where propeller motors can generate voltage due to rotation induced by the propeller, measures should be
taken to avoid disturbances or damage of components and systems.
9.2.3 Prime movers
9.2.3.1 Prime movers of any type shall be provided with a governor capable of maintaining the
pre-set steady speed within a range not exceeding 5 % of the rated full-load speed for load
changes from full-load to no-load.
Where the speed control of the propeller requires speed variation of the prime mover, the
governor shall be provided with means for local manual control as well as for remote control.
In case of parallel operation of generators, the governing system shall permit stable operation
to be maintained over the entire operational speed range of the prime movers.
61892-5 © IEC:2000(E) – 15 –
9.2.3.2 The prime mover rated power in conjunction with its overloading and load build-up
capabilities shall supply the power needed during transitional changes in operating conditions
of the electrical equipment due to manoeuvring and sea and weather conditions.
NOTE With respect to the above, special attention should be paid to diesel engines equipped with an exhaust gas-
driven turbine blower for supercharging.
9.2.3.3 When manoeuvring from full propeller speed ahead to full propeller speed astern with
the unit making full way ahead, the prime mover shall be capable of absorbing a portion of the
regenerated power without tripping due to overspeed.
The setting of the overspeed trip device shall be in accordance with the requirements of the
appropriate authority and the amount of the regenerated power to be absorbed agreed to by the
electrical and mechanical machinery manufacturers.
Means external to the mechanical and electrical rotating machinery should be provided in the
form of phantom or dynamic braking resistors, or ballast consumers to absorb excess amounts
of regenerated energy and to retard the speed of rotation of the propulsion motor.
NOTE 1 Alternatively, the amount of regenerated power may be limited by the action of the control system.
NOTE 2 This subclause contains requirements that have to be agreed between manufacturer and purchaser.
9.3 Generators, motors, semiconductor convertors and electric slip-couplings
9.3.1 Machine and equipment temperature and ventilation
9.3.1.1 When generators, motors or slip-couplings are fitted with an integral fan (see
IEC 60034-6) and are operated at speeds below the rated speed with full-load torque, full-load
current, full-load excitation, etc., temperature limits in accordance with table 2 of IEC 61892-3,
shall not be exceeded.
9.3.1.2 The temperature of the cooling air of machines provided with forced air ventilation, air
ducts or air filters shall be continuously monitored by means of direct reading thermometers
which are readable from outside the machine and by a remote audible alarm actuated by
suitable temperature detectors.
For machines with a closed circuit cooling method with a heat exchanger, the flow of primary
and secondary coolants shall be monitored.
Consideration shall be given to the necessity of providing equipment for detecting leakage of
cooling liquid in a machine enclosure and operating an associated alarm.
NOTE Alternatively, monitoring of the winding temperature plus alarm may be accepted in lieu of flow alarm.
9.3.1.3 If semiconductor convertors are fitted with forced-ventilation, monitoring means for the
cooling system shall be provided.
In case of failure of the cooling system, an alarm shall be given and the current shall be reduced
automatically. The alarm signal can be generated by the flow of the coolant, by the electrical supply
to the ventilator or by the temperature of the diodes and thyristors.
NOTE Override of the automatic reduction, if necessary, can be considered.
9.3.1.4 Stator windings of a.c. machines and interpole windings of d.c. machines, rated above
500 kW, shall be provided with temperature sensors.
– 16 – 61892-5 © IEC:2000(E)
9.3.2 Accessibility and facilities for repair in situ
9.3.2.1 For the purposes of inspection and repair, provision shall be made for access to the
stator and rotor coils and for the withdrawal and replacement of field coils.
9.3.2.2 Facilities shall be provided for supporting the shaft to permit inspection and
withdrawal of bearings.
9.3.2.3 Adequate access shall be provided to permit the resurfacing of commutators and slip-
rings, as well as the renewal and bedding of brushes.
9.3.2.4 Slip-couplings shall be designed to permit removal as a unit without axial
displacement of the driving and driven shaft, and without removing the poles.
9.3.2.5 Convertors shall be easily accessible and arranged for quick repair and exchange of
components.
9.3.3 Protection against moisture and condensate
Effective means shall be provided in propulsion machines and convertors to prevent
accumulation of moisture and condensate, even if they are idle for appreciable periods (for
example by means of space heaters).
9.3.4 Sudden short circuits
AC machines shall be capable of withstanding a short circuit at their terminals under rated
conditions without suffering damage.
9.3.5 Overspeed of propulsion motors
The rotor of propulsion motors shall be capable of withstanding overspeeding up to the limit
reached in accordance with the characteristics of the overspeed protection device at its normal
operational setting.
9.3.6 Exciter sets
The obtainable current and voltage of exciters and their supply shall be suitable for the output
required during manoeuvring and overcurrent conditions including short circuit.
For this reason, attention shall be paid to the strength of shafts and couplings of rotating sets
and the power of their driving machines.
9.3.7 Semiconductor convertor design data
9.3.7.1 The following limiting repetitive peak voltages shall be used as a base for the
semiconductor valve:
– when connected to a supply specifically for propeller drives, U = 1,5 U ;
RM P
when connected to a common main supply, U = 1,8 U
– RM P
(U is the peak value of the rated voltage at the input of the semiconductor convertor.)
P
If the semiconductors are connected in series, the value mentioned above shall be increased
by 10 %. Equal voltage distribution shall be ensured.
61892-5 © IEC:2000(E) – 17 –
9.3.7.2 When semiconductor convertors are used, means shall be taken, where necessary, to
limit the effect of disturbances, both to the system and to other semiconductor convertors. The
following are example of items that should be considered in relation to limiting the effect of
disturbances:
– convertors when connected to the same busbar system;
– commutation reactance which, if insufficient, may result in voltage distortion adversely
affecting other consumers on the system;
– the relation between the system subtransient reactance and the convertor;
– commutation reactance: unsuitable matching may result in the production of voltage
harmonics which could cause overheating of other consumers;
– any adverse effect of convertors on the commutation of d.c. machines;
– any adverse effect, in the regenerating mode, if voltage drops on inverter operation;
– interference from high frequency noise.
When filter circuits and capacitors are used for reactive current compensation, the following
items should be considered:
– any adverse effect of frequency variation on the r.m.s. and peak values of the system
voltage;
– any adverse effect on the voltage regulation of generators.
9.3.7.3 The following protection of convertors shall be provided:
– overvoltage in a supply system to which convertors are connected shall be limited by
suitable devices to prevent damage. Protective fuses for these devices shall be monitored.
A suitable control shall ensure that the permissible current of semiconductor elements
cannot be exceeded during normal operation;
– short circuit currents shall be limited by specially adapted fuses. These semiconductor
protective fuses shall be monitored. In case of fuse operation, the respective part of the
plant shall be taken out of operation;
– fuses in filter circuits shall be monitored.
NOTE Consideration should be given to include excessive current ripple in the scheme of protection.
9.4 Controlgear
9.4.1 Location of manoeuvring controls
The main propulsion manoeuvring controls shall be located at a convenient place.
Whenever control outside the engine room is applied, an arrangement shall be provided
whereby the propulsion plant can also be controlled from the engine room, or control room.
NOTE In systems equipped with variable pitch propellers, pitch indication should be integrated in the main control
station.
9.4.2 Engine order systems
Engine order systems shall be provided on self-propelled units.
NOTE Engine order telegraph systems or other means of engine order systems in accordance with the appropriate
authorities can be considered.
– 18 – 61892-5 © IEC:2000(E)
9.4.3 Operation of manoeuvring controls
Either manual operation or operation with the aid of power or a combination of both shall be
used.
In the case of manual operation, all manoeuvring switches, field-regulators and controllers
shall be operable without undue effort.
If failure of power supply occurs in systems with power-aided control (e.g. with electric,
pneumatic or hydraulic aid), it shall be possible to restore control in a short time.
When two or more control stations are provided outside the engine room, a selector switch or
other means shall be provided for transferring the manoeuvring controls to the designated
station.
Indication of which control station is in command shall be provided at the selector switch and at
each control station. Simultaneous control from more than one control station shall not be
possible.
Except for systems in which t
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