IEC 60092-501:2007

IEC 60092-501
Edition 4.0 2007-08
INTERNATIONAL
STANDARD
Electrical installations in ships –
Part 501: Special features – Electric propulsion plant

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IEC 60092-501
Edition 4.0 2007-08
INTERNATIONAL
STANDARD
Electrical installations in ships –
Part 501: Special features – Electric propulsion plant

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
V
ICS 47.020.060 ISBN 2-8318-9245-7

– 2 – 60092-501 © IEC:2007(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6

1 Scope.7
2 Normative references .7
3 Terms and definitions .8
4 System .9
4.1 System design.9
4.2 System responsibility.11
4.3 Torsional stress and torsional vibrations.11
4.4 Operational stability .11
4.5 Protection against moisture and condensate .12
4.6 Excitation systems .12
4.7 Wires, cables, busbars, trunking systems .12
5 Electromagnetic compatibility (EMC) and harmonic distortion .13
5.1 General .13
5.2 Total harmonic distortion, THD .13
5.3 Radio frequency interferences .13
6 Prime movers .13
6.1 General requirements.13
6.2 Speed deviations.14
6.3 Parallel operation .14
6.4 Reverse power .14
7 Generators .14
7.1 General requirements.14
7.2 Bearing and lubrication.14
7.3 Cooling.15
7.4 Protection.15
7.5 Test.15
8 Propulsion switchboards.15
9 Propulsion transformers .16
9.1 General requirements.16
9.2 Cooling.16
9.3 Instrumentation .17
9.4 Protection.17
9.5 Test.17
10 Convertors .17
10.1 General .17
10.2 Design of semiconductor convertors.17
10.3 Cooling of semiconductor convertors.18
10.4 Protection.18
10.5 Test.18
11 Harmonic filtering .18
12 Propulsion motors .19
12.1 General requirements.19

60092-501 © IEC:2007(E) – 3 –
12.2 Bearing and lubrication.19
12.3 Cooling of propulsion motors .19
12.4 Protection.19
12.5 Test.20
12.6 Short-circuit withstand capability .20
12.7 Accessibility and facilities for repairs in situ.20
13 Special requirements for podded drives.20
13.1 General requirements.20
13.2 Sensors.21
13.3 Protection of the propulsion motor.22
13.4 Air humidity .22
13.5 Motor supply lines .22
13.6 Slip rings .22
13.7 Azimuth drive .23
14 Control .24
14.1 Power management system (PMS) .24
14.2 Typical control configuration.24
14.3 Location of manoeuvring controls .26
14.4 Main and local control station .26
14.5 Measuring-, indicating- and monitoring equipment.26
14.6 Availability.27
15 Tests .28
15.1 General .28
15.2 In-process-tests .28
15.3 Factory acceptance test .28
15.4 Dock and sea trials.28
16 Documentation .29

Annex A (normative) Alarm-matrix .30

Figure 1 – Typical equipment (configuration) for ships with one or two propellers .10
Figure 2 – Typical control configuration .25

Table A.1 – Alarm matrix for permanent excited motors .30
Table A.2 – Alarm matrix for synchronous motors .31
Table A.3 – Alarm matrix for asynchronous motors .33
Table A.4 – Alarm matrix for d.c. motors .34

– 4 – 60092-501 © IEC:2007(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSTALLATIONS IN SHIPS –

Part 501: Special features –
Electric propulsion plant
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60092-501 has been prepared by IEC technical committee 18:
Electrical installations of ships and of mobile and fixed offshore units.
This fourth edition cancels and replaces the third edition published in 1984. It constitutes a
technical revision.
This edition included the following significant technical changes with respect to the previous
edition:
a) requirements regarding system responsibility, electromagnetic compatibility (EMC),
harmonic distorsion and filtering, special requirements for ships with propulsion motor(s)
and podded drives, and power management system (PMS);
b) overall technical review to update the standard according to general requirements and
referenced equipment standards.

60092-501 © IEC:2007(E) – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
18/1057/FDIS 18/1063/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 60092 series, under the general title Electrical installations in
ships, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

– 6 – 60092-501 © IEC:2007(E)
INTRODUCTION
IEC 60092 forms a series of international standards for electrical installations in sea-going
ships, incorporating good practice and coordinating, as far as possible, existing rules. These
standards form a code of practical interpretation and amplification of the requirements of the
International Convention on Safety of Life at Sea, a guide for future regulations which may be
prepared and a statement of practice for use by shipowners, shipbuilders and appropriate
organizations.
60092-501 © IEC:2007(E) – 7 –
ELECTRICAL INSTALLATIONS IN SHIPS –

Part 501: Special features –
Electric propulsion plant
1 Scope
This part of IEC 60092 specifies requirements for all electric propulsion plant and gives the
specifications, system design, installation and testing of at least
• generators and their prime movers;
• switchboards;
• transformers/reactors;
• semiconductor convertors;
• propulsion motors;
• excitation systems;
• control, monitoring and safety systems;
• wires, cables, busbars, trunking systems.
Bow and stern thrusters intended as auxiliary steering devices, booster and take-home
devices, all auxiliary generating plants, and accumulator battery powered propulsion
machinery and equipment are excluded.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60034 (all parts), Rotating electrical machines
IEC 60034-1:2004, Rotating electrical machines – Part 1: Rating and performance
IEC 60076 (all parts), Power transformators
IEC 60092 (all parts), Electrical installations in ships
IEC 60092-101, Electrical installations in ships – Part 101: Definitions and general
requirements
IEC 60092-202, Electrical installations in ships – Partie 202: System design – Protection
IEC 60092-204, Electrical installations in ships – Part 204: System design – Electric and
electrohydraulic steering gear
IEC 60092-301, Electrical installations in ships – Part 301: Equipment – Generators and
motors
IEC 60092-302, Electrical installations in ships –Part 302: Low-voltage switchgear and
controlgear assemblies
– 8 – 60092-501 © IEC:2007(E)
IEC 60092-303, Electrical installations in ships – Part 303: Equipment - Transformers for
power and lighting
IEC 60092-504:2001, Electrical installations in ships – Part 504: Special features – Control
and instrumentation
IEC 60146 (all parts), Semiconductor convertors
IEC 60146-2, Semiconductor convertors – Part 2:Self-commutated semiconductor converters
including direct d.c.converters
IEC 61000-6-2, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –
Immunity for industrial environments
IEC 61378-1, Convertor transformers – Part 1: Transformers for industrial applications
IEC 62271-200:2003, High-voltage switchgear and controlgear – Part 200: A.C. metal-
enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including
52 kV
International Maritime Organization, International convention of the safety of life at sea
(SOLAS):2004, Chapter II-I/ Regulations 27, 29 and 30
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply:
3.1
azimuth drive
system which moves the propulsion unit around the vertical axis
3.2
double sensor
two sensor elements in one housing
3.3
local control station
place of control where a system is installed which creates a reference value for the convertors
independent from the remote control system and any external limitations
3.4
locked electrical spaces
spaces constructed as dry spaces which are provided with lockable doors and are intended
solely for installation of electrical equipment
3.5
main control station
place of control of the main propulsion system which is manned under seagoing conditions
3.6
nominated body
installer or manufacturer that has been given direct responsibility for the complete propulsion
system.
60092-501 © IEC:2007(E) – 9 –
3.7
one failure principle
during and after a fault in a circuit, the supply to the healthy circuits is permanently ensured
(continuity of supply) and after a fault in a circuit has been cleared, the supply to the healthy
circuits is re-established (continuity of service)
3.8
podded drive
propulsion system in which the motor is located in a dedicated, submerged unit (pod housing)
of the ship
3.9
power management system (PMS)
control and safety system which provides the load depending starts and stops of the prime
movers, the load sharing, etc.
3.10
propulsion generator
generator mainly used for power supply of the propulsion system
3.11
propulsion motor
electrical motor intended to provide propulsion power
3.12
propulsion switchboard
switchboard mainly used for power distribution to the propulsion systems
3.13
redundant sensor
two single sensors in separate housings
3.14
remote control system
system which comprises all equipment necessary to operate units from a control position
where the operator cannot directly observe the effect of his actions
4 System
4.1 System design
4.1.1 General
A typical electrical propulsion system consists of the following hardware components:
• propulsion generators;
• switchboard;
• transformers to convert the ships voltage to the convertor voltage;
• convertor to supply the electric motor;
• control system;
• propulsion motor
A typical configuration of the hardware components is shown in Figure 1.

– 10 – 60092-501 © IEC:2007(E)

One propeller Two propellers
IEC  1287/07
Key
1 Main engine 4 Propulsion transformer 7 Propeller
2 Propulsion generator 5 Propulsion convertor
3 Switchboard 6 Propulsion motor
Figure 1 – Typical equipment (configuration) for ships with one or two propellers
4.1.2 Design requirements
The one failure principle shall be the basis of the design.
NOTE Recognizable failures should not injure the one failure principle. Undetected failures should be avoided.
However, it may be unavoidable that some undetected failures may injure the one failure principle.
It shall be possible for all machinery essential for the safe operation of the ship to be
controlled from a local position, even in the case of failure in any part of the automatic remote
control system, see Clause 14.
4.1.3 Special requirements for ships with only one propulsion motor
Synchronous and induction motors shall be equipped with two stator winding systems which
can be disconnected from the respective convertor. Each convertor shall be designed for at
least 50 % nominal power of the propulsion drive.
DC motors shall have two separate rectifiers, each for 50 % nominal motor current, with
means for disconnecting each rectifier. The convertors shall be mutually independent. Any
single failure in one convertor shall not result in complete loss of propulsion power.
Motors with permanent excitation shall be equipped with two stator winding systems which
can be disconnected from the respective convertor. Additionally, there shall be a braking or

60092-501 © IEC:2007(E) – 11 –
blocking system which can fix the shaft under all weather and normal towing conditions.
Alternatively, a decoupling system may be used which ensures standstill of motor shaft.
4.1.4 Special requirements for ships with more than one propulsion motor
Any electrical failure in a propulsion convertor or propulsion motor shall not make all shafts
unavailable.
For all types of propulsion, there shall be a braking or blocking system which can fix the shaft
under all weather conditions, propulsion by the remaining shafts and normal towing
conditions.
4.2 System responsibility
There shall be one nominated body responsible for the integration of the complete propulsion
system.
This body shall have the necessary expertise and resources enabling a controlled integration
process.
4.3 Torsional stress and torsional vibrations
In order to prevent excessive torsional stresses and torsional vibrations of excessive
magnitude, careful consideration shall be given to co-ordination of the moments of inertia and
the elasticity constants of the entire propulsion system, and electrical characteristics in the
system.
The entire oscillating system may include prime movers, generators, transformers, convertors,
exciters, motors, slip-couplings, gears, shafts and propellers.
The manufacturers of the components shall provide all necessary information to the system
responsible body, see 4.2.
The highest oscillating torque can be expected in case of two-phase short circuit of the motor.
The highest steady state torque can be expected in case of three-phase short circuit of the
motor.
NOTE It is assumed that torque during short circuit conditions will be less than the torque during the crash stop
manoeuvre
These possible load situations shall be managed by the propulsion plant. Evidence shall be
made by torsional vibration calculation.
4.4 Operational stability
The control system shall be able to control the propulsion system under all weather and
manoeuvring conditions.
Other onboard systems shall not influence the propulsion or manoeuvrability of the ship, for
example no common communication links, no common hardware. Special consideration shall
be given to electromagnetic interference.
All means for normal operation of the propulsion system, including necessary power
generation, shall have interlocks in order to prevent incorrect operation and damages.

– 12 – 60092-501 © IEC:2007(E)
4.5 Protection against moisture and condensate
Effective means, for example space heaters or air dryers, shall be provided in motors,
generators, convertors, transformers and switchboards to prevent accumulation of moisture
and condensate, even if they are idle for appreciable periods.
Propulsion motors shall be equipped with an electric heating designed to maintain the
temperature inside the machine at about 3 K above ambient temperature.
4.6 Excitation systems
4.6.1 General requirements
Every excitation system shall be supplied by a separate feeder.
The obtainable current and voltage of excitation systems and their supply shall be suitable for
the output required during manoeuvring, overcurrent and short circuit or stalling conditions.
Excitation power circuits may be protected against short circuits only, and tripping shall be
alarmed.
If the built-in short-circuit monitoring device of the excitation system trips, the respective
circuit breaker of the generator or motor shall also trip.
If the excitation system is fitted with independent safety devices, for example against under-
frequency and over-voltage or voltage/frequency-functions, they shall be adjusted in such a
way that the system protection reacts first.
Excitation circuits shall be provided with means for suppressing voltage rise when an
excitation switch is opened.
Special consideration shall be given to the total harmonic distortion and power factor.
4.6.2 Generators
The steady and transient regulation conditions of the excitation system including the
automatic voltage regulator shall be in accordance with IEC 60092-301.
Excitation systems shall be supplied from the generator side and the generator shall be self-
excited. In general, the voltage built up shall be done without the aid of an external electric
power source.
External power supply may be used for exciter control circuits provided that redundancy for
this external source is arranged, even for the voltage built up. The external source of power
shall be supplied from the corresponding main switchboard section and emergency source of
electrical power with battery back up. At least two external power supplies for all generators
are required. Every generator excitation system shall be supplied by independent power
supply.
4.6.3 Propulsion motors
It shall be possible to supply the exciter circuits from the same switchboard section supplying
the stator windings.
4.7 Wires, cables, busbars, trunking systems
Cables and insulated conductors used for internal wiring shall be at least of a flame retardant
type. In case of wiring adjacent to equipment containing hydraulic or other oils, the insulation

60092-501 © IEC:2007(E) – 13 –
shall be resistant to that oil, or be properly shielded from it. The cables and insulated
conductors shall also be resistant to sea air containing moisture and salt and seawater and
they shall be not hygroscopic. They shall also be able to withstand the vibration levels and the
temperatures at the location installed and they shall be able to withstand internal and external
short-circuits. This also applies to singles wires of cables within terminal boxes.
For all electrical components and installations, materials shall be used that minimize the
emission of smoke, soot and toxic gases in case of fire.
Bus-bar systems for power transport shall be either certified for lifelong operation without
service, or all joints shall be accessible for inspection and maintenance.
In locations where cables may be subjected to mechanical damage, they shall be protected
with special reliable covers or shall be installed in metallic pipes.
5 Electromagnetic compatibility (EMC) and harmonic distortion
5.1 General
Propulsion systems shall comply with performance criterion A of IEC 61000-6-2. This means
no degradation of performance or loss of function is allowed during normal operation.
5.2 Total harmonic distortion, THD
Equipment producing transient voltage, frequency and current variations is not to cause
malfunction of other equipment on board, neither by conduction, induction or radiation.
The design shall take in account that propulsion convertors create interferences within the
propulsion network.
For the propulsion network the total harmonic distortion (THD) value of the voltage shall not
exceed 10 %. If a THD-value of 10 % is exceeded, the person responsible for the propulsion
system, see 4.2, shall ensure interference-free operation of all connected equipment. If the
propulsion network and the ship's network are directly connected the THD value of the voltage
shall not exceed the values stated in IEC 60092-101.
The design of cabling and cables, transformers, protection devices etc. shall take into account
the high level of harmonic currents caused by the convertor system.
5.3 Radio frequency interferences
If convertors for propulsion plants are placed in separate rooms or cabinets, the maximum
values for emissions are valid only outside these rooms or cabinets. The immunity
requirements of the propulsion convertor shall comply with at least the requirements for all
other equipment on board.
Conducted and radiated emissions leaving the convertor cabinet or room shall be reduced to
a system-compatible level.
6 Prime movers
6.1 General requirements
The engines driving the propulsion generators are the main engines.
Main engines shall comply with the specifications of the relevant authorities.

– 14 – 60092-501 © IEC:2007(E)
6.2 Speed deviations
If the propulsion generators are also used for supplying the ship network, static and dynamic
frequency deviations shall meet the requirements of the ship network.
Where the speed control of the propeller requires speed variation of the prime mover, the
governor shall be provided with means for local control as well as for remote control.
The prime mover rated power in conjunction with its overloading and load build-up capabilities
shall be adequate to supply the power needed during transitional changes in operating
conditions of the electrical equipment due to manoeuvring and sea and weather conditions.
6.3 Parallel operation
In case of parallel operation of generators, the governing system used shall permit stable
operation to be maintained over the entire operational load range of the prime-movers.
The speed governor characteristics of prime movers shall be such that in parallel operation
the load on individual generators is shared, as far as possible, in proportion to the output of
each generator.
6.4 Reverse power
When manoeuvring, for example from full propeller speed ahead to full propeller speed astern
with the ship making full way ahead, the prime-mover shall be capable of absorbing a
proportion of the regenerated power without tripping due to overspeed or reverse power.
Means external to the mechanical and electrical rotating machinery may be provided in the
form of for example braking resistors to absorb excess amounts of regenerated energy and to
reduce the speed of the propulsion motor.
The amount of regenerated power shall be limited by the control system.
7 Generators
7.1 General requirements
Generators shall be designed in accordance with the IEC 60034 series and IEC 60092-301.
Generators shall have a protection degree of at least IP 23. Medium voltage generators shall
have a protection degree of at least IP 44.
Generators operating with semiconductor convertors shall be designed for the expected
harmonics of the system. A sufficient reserve shall be considered for the temperature rise,
compared with sinusoidal load.
Stator windings of generators rated above 500 kVA shall be provided with temperature
sensors.
Generators above 1 500 kVA shall be equipped with differential current protection.
7.2 Bearing and lubrication
7.2.1 General
All bearings shall be equipped with temperature indicators. The measuring point shall be as
specified in IEC 60034-1.
60092-501 © IEC:2007(E) – 15 –
Adequate lubrication shall be ensured even in inclined positions. Provision shall be made for
checking the bearing lubrication.
Generators shall be equipped with devices which, in the event of a failure of the normal
lubricating oil supply, provide adequate lubrication until the machine has come to standstill.
No lubricating liquid shall flow out of the bearings and penetrate into the machine.
In case of bearings with forced lubrication, failure of the oil supply (loss of oil pump, loss of
pressure in the bearing supply pipe) and the attainment of excessive bearing temperatures,
an alarm shall be given. If the temperature rises further, the generator shall be stopped.
To avoid damage to bearings, it is essential to ensure that no harmful currents can flow
between bearings and shaft.
7.2.2 Sleeve bearings
Sleeve bearings shall be easily replaceable.
Two-part bearings shall be fitted with thermometers indicating, wherever possible, the
temperature of the lower bearing shell.
7.2.3 Roller bearings
Roller bearings shall be sufficiently preloaded, where applicable.
7.3 Cooling
The temperature of the cooling air of machines provided with forced air ventilation, air ducts,
air filters or water coolers shall be continuously monitored by means of thermometers which
are readable from outside the machine. Temperature sensors shall be provided to trigger an
alarm.
For machines with a closed circuit cooling method with a heat exchanger, the flow of primary
and secondary coolants shall be monitored.
Leakage-water and condensed moisture shall be kept away from the windings. Leakage
monitoring is required.
7.4 Protection
The protection shall be in accordance with IEC 60092-202.
7.5 Test
Propulsion generators shall be individually tested at the manufacturer's works. The scope of
the tests is stated in the IEC 60034 series.
The additional heating caused by total harmonic distortion shall be taken into account during
the temperature rise test.
8 Propulsion switchboards
The propulsion switchboard shall be in accordance with IEC 62271-200 (high voltage)
adapted to shipbuilding requirements or IEC 60092-302 (low voltage) and shall be designed
like a main switchboard. The longitudinal segregation of the bus bar shall be done by a load
switch disconnector or equivalent equipment.

– 16 – 60092-501 © IEC:2007(E)
Special consideration shall be given to the total harmonic distortion, see 5.2, and power
factor.
9 Propulsion transformers
9.1 General requirements
9.1.1 General
Transformers and reactors shall be in accordance with IEC 60092-303 and power
transformers in accordance with IEC 61378-1 and the IEC 60076 series.
Special consideration shall be given to the total harmonic distortion, see 5.2, and power
factor.
At least two independent propulsion transformers shall be installed.
Only transformers with separate windings shall be used. Auto transformers are permitted for
motor starting.
Transformers producing low voltage from medium voltage shall be equipped with an earthed
shield winding between the low-voltage and medium-voltage coil.
The winding temperatures of propulsion transformers shall be monitored.
9.1.2 Degree of protection
Transformers located in engine rooms shall have a protection degree of at least IP 23.
Medium voltage transformers, located in engine rooms, shall have a protection degree of at
least IP 44.
All transformers located in dedicated locked electrical spaces may have any degree of
protection of at least IP 20.
9.2 Cooling
9.2.1 Liquid cooled transformers
Measures shall be taken to ensure that the windings are completely covered by liquid, even
for inclinations up to and including 22,5°.
They shall be provided with a collecting arrangement which permits the proper disposal of the
liquid.
A fire detector and a suitable fire extinguishing system shall be installed in the vicinity of the
transformer. The fire fighting system may be manually operated.
Liquid cooled transformers shall be provided with gas-actuated protection devices.
The liquid temperature shall be monitored. A prealarm shall be actuated before the maximum
permissible temperature is attained. When the maximum permissible temperature limit is
reached, the transformer shall be switched off.
The liquid filling level shall be monitored by means of two separate sensors. The monitoring
system shall actuate an alarm at the first stage and shall trigger a shutdown at the second
stage, when the permissible limit is exceeded.

60092-501 © IEC:2007(E) – 17 –
9.2.2 Air cooled transformers
Ventilators and temperatures of the cooling air for forced-ventilated transformers shall be
monitored.
9.2.3 Air forced/water forced cooled transformers
For transformers with a closed circuit cooling method with a heat exchanger, the flow of
primary and secondary coolants shall be monitored. Leakage-water and condensed moisture
shall be kept away from the windings. Leakage monitoring is required.
9.3 Instrumentation
Propulsion transformers shall be equipped with a three-phase ammeter on primary side.
9.4 Protection
Each propulsion transformer shall be protected against overcurrent and short-circuit at the
primary and secondary side.
Protection on secondary side may be achieved by the convertor.
9.5 Test
Propulsion transformers shall be individually tested at the manufacturer's works. The scope of
the tests including the vector-group test is stated in IEC 61378-1.
The additional heating caused by total harmonic distortion, see 5.2, shall be taken into
account during the temperature rise test.
10 Convertors
10.1 General
Convertors shall be designed in accordance with the IEC 60146 series.
Two entirely separate convertors shall be installed.
Common control of the convertors is not permitted. This means, for example, that two single
tachometer generators or one doubled tachometer generator shall be installed if a tachometer
generator is needed for ship’s operation.
Two galvanically isolated actual speed sensors shall be provided for each control system.
Common housing of both sensors is permitted.
If the convertor feeds a permanently excited synchronous motor, a switch disconnector shall
be fitted in the motor-convertor line which opens automatically in case of an inverter fault.
Devices which support fault diagnosis shall be installed.
10.2 Design of semiconductor convertors
Propulsion convertors shall be designed for the nominal torque of the drive. Short-term
overload and speed variations resulting from overloads shall not lead to a shutdown of the
system.
The cabinets for semiconductor convertors shall meet the standards of the main switchboard.

– 18 – 60092-501 © IEC:2007(E)
High voltage convertors shall be treated like high voltage switchgear and control gear in
accordance with IEC 62271-200 adapted to shipbuilding requirements. The enclosures shall
be manufactured to withstand accidental arcs in accordance with Annex A of IEC 62271-200,
or shall be located that personnel safety is ensured.
The power components for semiconductor convertors shall be easy replaceable.
10.3 Cooling of semiconductor convertors
If semiconductor convertors are fitted with forced-cooling, means for monitoring the cooling
system shall be provided.
In case of a failure of the cooling system, measures shall be taken to prevent damage to the
convertor. An alarm shall be given. The alarm signal can be generated by the flow of the
coolant, or by the temperature of the semiconductors.
Single failures in convertor cooling systems shall not lead to the tripping of all convertors of
the ship's propulsion.
10.4 Protection
The following protection of convertors shall be provided:
Operational overvoltages 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.
Semiconductors shall not be damaged by direct short circuit at the terminals. Protection by
fuses is permitted. The convertor shall control the current in such a way that no components
are damaged when the convertor is switched on to a blocked motor.
10.5 Test
Convertors shall be individually tested at the manufacturer's works. The scope of the tests,
for example functional test, adjustments, limitations, failure handling, is stated in IEC 60146-
2.
11 Harmonic filtering
Line filters can be used to ensure the required harmonic distortion in the mains at any step of
propulsion.
Each individual filter circuit shall be protected
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