Section
10 Converter equipment
10.1 Transformers
10.1.2 Transformers are to comply with the requirements of the following
standards:
-
IEC 60076 (all parts): Power transformers (all parts);
-
IEC 60092-503: Electrical installations in ships – Part 503:
Special features – AC supply systems with voltages in the range of above 1 kV
up to and including 36 kV; or
-
an acceptable and relevant National Standard amended where necessary
for ambient temperature, see
Pt 6, Ch 2, 1.9 Ambient reference and operating conditions.
10.1.3 Transformers may be of the dry type, encapsulated or liquid-filled
type.
10.1.4 The temperature rise of the winding of transformers above the ambient
temperatures given in Pt 6, Ch 2, 1.9 Ambient reference and operating conditions, when measured by resistance during continuous
operation at the maximum rating, is not to exceed:
-
For dry type transformers, air cooled:
insulation of Class A - 50°C
insulation of Class E - 60°C
insulation of Class B - 70°C
insulation of Class F - 90°C
insulation of Class H - 110°C
-
For liquid filled transformers:
50°C - where air provides cooling of the fluid
65°C - where water provides cooling of the fluid.
10.1.5 When a transformer is connected to a supply system with harmonic distortion,
the rating of the transformer is to allow for the increased heating effect of the
harmonic loading. Special attention is to be given to transformers connected for the
purpose of reducing harmonic distortion.
10.1.6 The inherent regulation of transformers at their rated output is to be such
that the total voltage drop to any point in the installation does not exceed that
allowed by Pt 6, Ch 2, 1.8 Quality of power supplies.
10.1.7 Transformers, except those for motor starting, are to be double wound.
10.1.8 Liquid fillings for transformers are to be non-toxic and of a type which
does not readily support combustion. Liquid filled transformers are to have a pressure
relief device with an alarm and there is to be a suitable means provided to contain any
liquid which may escape from the transformer due to the operation of the relief device
or damage to the tank.
10.1.9 All transformers are to be capable of withstanding for two seconds, without
damage, the thermal and mechanical effects of a short-circuit at the terminals of any
winding.
10.1.10 When forced cooling is used, whether air or liquid, there is to be
monitoring of the cooling medium and transformer winding temperatures with an alarm
should these exceed preset limits. There are to be arrangements so that the load may be
reduced to a level commensurate with the cooling available.
10.1.11 When oil-immersed transformers are used, there is to be monitoring for low oil level
with an alarm when pre-set limits are crossed. There are to be arrangements so that the
load may be reduced to a level commensurate with the cooling available.
10.1.12 Transformers for propulsion power are to be provided with arrangements such
that, in the event of excessive winding temperature, an alarm is initiated and:
- the load is reduced to a level commensurate with the cooling
arrangements; or
- automatic shutdown of the transformer occurs.
10.1.13 Where liquid-cooled heat exchangers are used in transformer cooling
circuits, there is to be provision to detect leakage of the liquid, and the system is to
be arranged so as to prevent the entry of liquid into the transformer.
10.1.14 The following tests are to be carried out on all transformers at the
manufacturer's works, and a certificate of tests issued by the manufacturer, see
also Pt 6, Ch 2, 1.4 Surveys 1.4.2 and Pt 6, Ch 2, 1.4 Surveys 1.4.3:
-
measurement of winding resistances, voltage ratio, impedance voltage,
short-circuit impedance, insulation resistance, load loss, no load loss and
current;
-
dielectric tests;
-
temperature rise test on one transformer of each size and type;
and
-
where evidence of compliance with Pt 6, Ch 2, 10.1 Transformers 10.1.9 is not submitted for consideration,
short-circuit withstand on one transformer of each size and type.
10.2 Semiconductor converters
10.2.3 Semiconductor
static power converters are to be rated for the required duty having
regard to peak loads, system transients and overvoltage.
10.2.4 Converter
equipment may be air or liquid cooled and is to be so arranged that
it cannot remain loaded unless effective cooling is maintained. Alternatively
the load may be automatically reduced to a level commensurate with
the cooling available.
10.2.5 Liquid cooled converter equipment:
- is to be provided with leakage alarms;
- is to be provided with a suitable means to contain any liquid which may leak from
the system, preventing the liquid from causing further electrical failures or
damage;
- where the semiconductors and other current carrying parts are in direct contact
with the cooling liquid, the system is to be provided with:
- suitable coolant resistivity/ conductivity monitoring;
- an alarm at the relevant control station, which is to be initiated if the
resistivity/ conductivity values exceed agreed limits; and
- used for main propulsion is to have a shutdown to prevent damage to the converter
if the cooling liquid exceeds agreed safe limits of resistivity/ conductivity.
See also
Pt 6, Ch 1, 2.6 Bridge control for main propulsion machinery 2.6.8.
10.2.6 Where
forced cooling is used there is to be temperature monitoring of the
heated cooling medium with an alarm and shutdown when the temperature
exceeds a preset value.
10.2.7 Cooling
fluids are to be non-toxic and of low flammability.
10.2.8 Converter
equipment is to be so arranged that the semiconductor devices, fuses,
control and firing circuit boards may be readily removed from the
equipment for repair or replacement.
10.2.9 Test
and monitoring facilities are to be provided to permit identification
of control circuit faults and faulty components.
10.2.10 Protection
devices fitted for converter equipment protection are to ensure that,
under fault conditions, the protective action of circuit-breakers,
fuses or control systems is such that there is no further damage to
the converter or the installation.
10.2.11 Converter
equipment, including any associated transformers, reactors, capacitors
and filters, if provided, is to be so arranged that the harmonic distortion,
and voltage spikes, introduced in to the ships electrical system are
within the limits of Pt 6, Ch 2, 1.8 Quality of power supplies 1.8.3 or
restricted to a lower level necessary to ensure that it causes no
malfunction of equipment connected to the electrical installation.
10.2.12 Overvoltage
spikes or oscillations caused by commutation or other phenonema, are
not to result in the supply voltage waveform deviating from a superimposed
equivalent sine wave by more than 10 per cent of the maximum value
of the equivalent sine wave.
10.2.13 When
converter equipment is operated in parallel, load sharing is to be
such that under normal operating conditions overloading of any unit
does not occur and the combination of paralleled equipment is stable
throughout the operating range.
10.2.14 When
converter equipment has parallel circuits there is to be provision
to ensure that the load is distributed uniformly between the parallel
paths.
10.2.15 Transformers,
reactors, capacitors and other circuit devices associated with converter
equipment, or associated filters, are to be suitable for the distorted
voltage and current waveforms to which they may be subjected and filter
circuits are to be provided with facilities to ensure that their capacitors
are discharged before the circuits are energised.
10.2.16 Any
regenerated power developed during the operation of converter equipment
is not to result in disturbances to the supply system voltage and
frequency which exceeds the limits of Pt 6, Ch 2, 1.8 Quality of power supplies.
10.2.17 Where
control systems form an integral part of semiconductor equipment,
they are to be designed and manufactured with regard to the environmental
conditions to which they will be exposed in service and their performance
is to be demonstrated during the test and trials programme.
10.2.18 Tests at the manufacturer's works of converter equipment and any associated
reactors or filters are to include the high voltage test of Pt 6, Ch 2, 21.1 Testing a temperature rise test, on one of each size and
type of converter equipment, and such other tests as may be necessary to demonstrate the
suitability of the equipment for its intended duty. Details of tests are to be submitted
for consideration when required, see also
Pt 6, Ch 2, 1.4 Surveys 1.4.2.
10.3 Uninterruptible power systems
10.3.2 UPS
units are to be constructed in accordance with IEC 62040: Uninterruptible
power systems (UPS) (all parts), or an acceptable and relevant
National or International Standard.
10.3.3 The
operation of a UPS is not to depend upon external services.
10.3.4 The
type of UPS unit employed, whether off-line, line-interactive or on-line,
is to be appropriate to the power supply requirements of the connected
load equipment.
10.3.5 An
external bypass, that is hardwired and manually operated, is to be
provided for UPS to allow isolation of UPS for safety during maintenance
and maintain continuity of load power.
10.3.6 UPS
units are to be monitored and an audible and visual alarm is to be
initiated in the navigating bridge or the engine control room, or
an equivalent attended location for:
- power supply failure (voltage and frequency) to the connected
load;
- earth fault;
- operation of battery protective device;
- battery discharge; and
- bypass in operation for on-line UPS units.
10.3.7 UPS
units required to provide emergency services are to be suitably located
for use in an emergency.
10.3.8 UPS
units utilising valve-regulated sealed batteries may be located in
compartments with standard marine or industrial electrical equipment
provided that the arrangements comply with Pt 6, Ch 2, 12.3 Location 12.3.5. Ventilation arrangements
in accordance with IEC 62040-1: Uninterruptible power systems
(UPS) – Part 1: General and safety requirements for UPS,
or an acceptable and relevant National or International Standard,
may be considered to satisfy the requirements of Pt 6, Ch 2, 12.5 Thermal management and ventilation 12.5.10.
10.3.9 Output
power is to be maintained for the duration required for the connected
equipment.
10.3.10 The
UPS battery capacity is, at all times, to be capable of supplying
the designated loads for the time specified. Where it is proposed
that additional circuits are connected to the UPS unit, details verifying
that the UPS unit has adequate capacity are to be submitted for consideration, see
Pt 6, Ch 2, 1.5 Additions or alterations.
10.3.11 On
restoration of the input power, the rating of the charge unit is to
be sufficient to recharge the batteries while maintaining the output
supply to the load equipment.
10.3.12 Tests
at the manufacturer’s works or after installation on board are
to include such tests necessary to demonstrate, to the Surveyor’s
satisfaction, the suitability of the UPS unit for its intended duty
and location. As a minimum the following tests are required:
- a temperature rise test;
- battery capacity test;
- a ventilation rate test of both the equipment housing and the
space into which it is to be located, see also
Pt 6, Ch 2, 12.5 Thermal management and ventilation; and
- functional testing, including operation of alarms.
Details of tests are to be submitted for consideration when
required, see also
Pt 6, Ch 2, 1.4 Surveys 1.4.2.
10.3.13 Where
the supply is to be maintained without a break following a power input
failure, this is to be verified after installation by practical testing.
10.3.14 UPS units utilising lithium battery systems as energy storage devices are to be in
accordance with the following sub-Sections of these Rules as applicable and to the
recommendations of the battery manufacturer:
- Pt 6, Ch 2, 1.2 Documentation required for design review;
- Pt 6, Ch 2, 12.1 General;
- Pt 6, Ch 2, 12.2 Design and construction;
- Pt 6, Ch 2, 12.3 Location;
- Pt 6, Ch 2, 12.4 Installation;
- Pt 6, Ch 2, 12.5 Thermal management and ventilation and
- Pt 6, Ch 2, 21.1 Testing.
|