Section
9 Rotating machines
9.1 General requirements
9.1.1 In addition to the requirements of this Section, rotating machines are to comply with
the relevant requirements of the following standards, amended where necessary for
ambient temperature, see Pt 6, Ch 2, 1.9 Ambient reference and operating conditions:
- IEC 60034 Rotating electrical machines (all parts);
and
- IEC 60092: Electrical installations in ships (all
parts); or
- an alternative International or National Standard acceptable to
LR.
9.1.2 The insulation systems of electrical rotating machines used for essential
services are to be tested following the principles detailed in IEC 60505, Evaluation
and qualification of electrical insulations systems, or an equivalent
International or National Standard acceptable to LR.
9.1.4 All machines of 100 kW and over, intended for essential services, are to be
surveyed by the Surveyor during manufacture and test, see also
Pt 6, Ch 2, 1.4 Surveys 1.4.6.
9.1.5 Shaft materials for rotating machines for essential services are to comply
with the
Rules for the Manufacture, Testing and Certification of Materials, July 2022
(hereinafter referred to as the Rules for Materials) and be manufactured under LR
survey for the following applications:
-
shaft material for dynamic positioning and electric propulsion
motors;
-
shaft material for main engine driven generators where the shaft is
part of the propulsion shafting; and
-
shaft material for machines with power ratings of 250 kW or
greater.
Shaft material for machines with power ratings less than 250 kW is to have
a manufacturer’s certificate as detailed in Ch 1 General Requirements of the Rules for Materials.
9.1.6 Where welding is applied to shafts of machines for securing arms or
spiders, stress relieving is to be carried out after welding. The finalised assembly is
to be visually examined by the Surveyors, crack detection carried out by an appropriate
method and the finished welds found sound and free from cracks.
9.1.7 The rotating parts of machines are to be so balanced that when running at
any speed in the normal working range the vibration does not exceed the levels of IEC
60034-14: Rotating electrical machines – Part 14: Mechanical vibration of certain
machines with shaft heights 56 mm and higher – Measurement, evaluation and limits of
vibration severity.
9.1.8 The lubrication arrangement for bearings are to be effective under all
operating conditions including the maximum ship inclinations defined by Pt 6, Ch 2, 1.10 Inclination of ship and
there are to be effective means provided to ensure that lubricant does not reach the
machine windings or other conductors and insulators.
9.1.9 Means are to be taken to prevent the ill effects of the flow of currents
circulating between the shaft and machine bearings or bearings of connected
machinery.
9.1.10 Alternating current machines are to be constructed such that, under any
operating conditions, they are capable of withstanding the effects of a sudden
short-circuit at their terminals without damage.
9.1.11 Propulsion motors, and generators that form part of electrical propulsion
systems, are to have at least one embedded temperature detector (ETD) in each phase of
the machine winding in locations which may be subjected to the highest temperature.
Where there are two coil sides per slot the ETD’s are to be located between the
insulated coil sides in the slot, see
Pt 6, Ch 2, 16.1 General 16.1.3.
9.1.12 A high bearing temperature alarm is to be provided for generators of 100 kW
and above, and electric propulsion motors, which are supplied with forced lubrication,
see also
Pt 6, Ch 2, 16.6 Protection of propulsion system 16.6.12 for second stage high temperature safe
shutdown to prevent damage.
9.1.13 A low lubricating oil pressure alarm is to be provided for generators and
electric propulsion motors that are supplied with forced lubrication.
9.1.15 For high voltage machines, the stator insulation system is to be of a type
that has undergone design qualification testing in accordance with the applicable
requirements of the following International Standards, or relevant alternatives
acceptable to LR, to demonstrate its suitability for the operating voltage:
- IEC 60034-18-31, Rotating electrical machines – Part 18-31:
Functional evaluation of insulation systems – Test procedures for form-wound
windings – Thermal evaluation and classification of insulation systems used in
rotating machines;
- IEC 60034-18-32, Rotating electrical machines – Part 18-32:
Functional evaluation of insulation systems – Test procedures for form-wound
windings – Evaluation by electrical endurance;
- IEC 60034-18-34, Rotating electrical machines – Part 18-34:
Functional evaluation of insulation systems – Test procedures for form-wound
windings – Evaluation of thermomechanical endurance of insulation
systems`;
- IEC 60034-27-3, Dielectric dissipation factor measurement on stator
winding insulation of rotating electrical machines.
Test samples are to be representative in terms of the number and size of
conductors, coil construction and the combination of materials and manufacturing
process.
9.1.16 The reference insulation system, against which the test samples in Pt 6, Ch 2, 9.1 General requirements 9.1.15 is to be validated, is to be have been
demonstrated to be suitable for use in the environmental conditions that the finished
machine will be exposed to in service. Documented evidence of such suitability is to be
available to the LR Surveyor, at the time these tests are conducted.
9.1.17 Sample coils for use in the machines detailed in Pt 6, Ch 2, 9.1 General requirements 9.1.15 are to be type tested and subsequently
routinely tested in accordance with the following International Standards, or relevant
alternatives acceptable to LR. The interval between routine tests is to be agreed with
LR, and testing is to be witnessed by an LR Surveyor:
- IEC 60034-27-3, Dielectric dissipation factor measurement on stator
winding insulation of rotating electrical machines; and
- IEC 60034-15: Rotating electrical machines – Part 15: Impulse
voltage withstand levels of form-wound stator coils for rotating a.c.
machines, with power-frequency voltage withstand testing conducted.
Test samples are to be representative in terms of the number and size of
conductors, coil construction, and the combination of materials and manufacturing
process.
9.1.19 Converter-fed high voltage machines intended for essential or emergency
services are to be designed for the in service operating conditions originating from the
converter. These are to include as a minimum, but are not limited to:
- maximum peak voltage and rise times;
- maximum voltage gradient;
- pulse repetition rate;
- voltage reflections; and
- fault conditions.
9.1.21 The completed stator of high voltage rotating machines to be used for
essential services are to be tested for partial discharge in accordance with IEC
60034-27-1, Rotating electrical machines Part 27-1: Off-line partial discharge
measurements on the winding insulation or an alternative standard acceptable to
LR. Copies of the test reports are to be provided to the Surveyor on request.
9.1.22 For high voltage rotating machines to be used for essential services,
suitable access is to be provided which will enable visual inspections of the stator and
field windings for signs of damage. Boroscopic and/or endoscopic inspection techniques
may be used where appropriate. Areas to be capable of inspection are to include, but are
not limited to:
- drive and non-drive ends of the machine;
- stator/core: core laminations; stator wedges; stator bars; space
blocks; end windings and connection rings; flux shield; instrumentation;
- field/frame: field wedges; retaining ring; coil end turns.
9.1.23 Where the requirements of Pt 6, Ch 2, 9.1 General requirements 9.1.22 cannot be
achieved, a means of connecting partial discharge monitoring equipment is to be
installed. The means of connection is to enable OFF-LINE periodic testing in accordance
with the recommendations of the rotating machine manufacturer and IEC 60034-27-1,
Rotating electrical machines Part 27-1: Off-line partial discharge measurements on
the winding insulation or an alternative standard acceptable to LR.
Alternatively, the requirements of Pt 6, Ch 2, 9.1 General requirements 9.1.24 may be
applied.
9.1.24 Where it is intended to install on-line partial discharge monitoring
equipment, the high voltage rotating machine installation is to be provided with a means
of connection which will enable the safe connection of the equipment once the rotating
machine is in service. The means of connection is to enable on-line through-life testing
in accordance with the recommendations of the rotating machine manufacturer and one of
the following standards:
- on-line testing:
- PD IEC/TS 60034-27-2, Rotating electrical machines Part 27-2:
On-line partial discharge measurements on the stator winding insulation of
rotating electrical machines;
- DD IEC/TS 61934: Electrical insulating materials and systems –
Electrical measurement of partial discharges (PD) under short rise time and
repetitive voltage impulses; or
- an alternative International or National Standard acceptable to LR.
9.1.26 The entity responsible for assembling the alternating current generating set is to
install a rating plate marked with at least the following information:
- the generating set manufacturer’s name or mark;
- the set serial number;
- the set date of manufacture (month/year);
- the rated power (both in kW and kVA) with one of the power rating prefixes COP, PRP
(or, only for emergency generating sets, LTP) as defined in ISO 8528-1
Reciprocating internal combustion engine driven alternating current generating
sets;
- the rated power factor;
- the set rated frequency (Hz);
- the set rated voltage (V);
- the set rated current (A); and
- the mass (kg).
9.2 Rating
9.2.1 Generators,
including their excitation systems, and continuously rated motors
are to be suitable for continuous duty at their full rated output
at maximum cooling air or water temperature for an unlimited period,
without the limits of temperature rise in Pt 6, Ch 2, 9.3 Temperature rise being exceeded. Generators are to be capable of an overload
power of not less than 10 per cent at their rated power factor for
a period of 15 minutes without injurious heating. Other machines are
to be rated in accordance with the duty which they have to perform
and, when tested under rated load conditions, the temperature rise
is not to exceed the values in Pt 6, Ch 2, 9.3 Temperature rise.
9.2.2 When
a rotating machine is connected to a supply system with harmonic distortion
the rating of the machine is to allow for the increased heating effect
of the harmonic loading.
9.2.3 The
design and construction of smoke extraction fan motors are to be suitable
for the ambient temperature and operating time required. Type test
reports to verify the performance of the electric motor are to be
submitted for consideration.
9.3 Temperature rise
9.4 Generator control
9.4.1 Each
alternating current generator, unless of the self-regulating type,
is to be provided with automatic means of voltage regulation; voltage
build-up is not to require an external source of power. Provision
is to be made to safeguard the distribution system should there be
a failure of the voltage regulating system resulting in a high voltage.
9.4.2 The
voltage regulation of any alternating current generator with its regulating
equipment is to be such that at all loads, from zero to full load
at rated power factor, the rated voltage is maintained within ±2,5
per cent under steady conditions. There is to be provision at the
voltage regulator to adjust the generator no load voltage.
9.4.3 Generators,
and their excitation systems, when operating at rated speed and voltage
on no-load are to be capable of absorbing the suddenly switched, balanced,
current demand of the largest motor or load at a power factor not
greater than 0,4 with a transient voltage dip which does not exceed
15 per cent of rated voltage. The voltage is to recover to rated voltage
within a time not exceeding 1,5 seconds.
Table 2.9.1 Limits of temperature rise of
machines cooled by air
| Limits of temperature rise of machines cooled by air,
°C
|
| Part of machine
|
Method of temperature measurement
|
Insulation class
|
| A
|
E
|
B
|
F
|
H
|
| 1.
|
(a)
|
a.c. windings of machines having
output of 5000 kVA or more
|
ETD
|
55
|
–
|
75
|
95
|
115
|
|
|
|
|
R
|
50
|
-
|
70
|
90
|
110
|
|
|
(b)
|
a.c. windings of machines having
output of less than 5000 kVA
|
ETD
|
55
|
–
|
80
|
100
|
115
|
|
|
|
|
R
|
50
|
65
|
70
|
95
|
110
|
| 2.
|
Windings
of armatures having commutators
|
R
|
50
|
65
|
70
|
95
|
115
|
|
|
|
|
T
|
40
|
55
|
60
|
75
|
95
|
| 3.
|
Field
windings of a.c. and d.c. machines having d.c. excitation other than those
in item 4
|
R
|
50
|
65
|
70
|
95
|
115
|
|
|
|
|
T
|
40
|
55
|
60
|
75
|
95
|
| 4.
|
(a)
|
Field windings of synchronous machines
with cylindrical rotors having d.c. excitation
|
R
|
–
|
–
|
80
|
100
|
125
|
|
|
(b)
|
Stationary field windings of d.c. machines
having more than one layer
|
R
|
50
|
65
|
70
|
95
|
115
|
|
|
|
|
T
|
40
|
55
|
60
|
75
|
95
|
|
|
(c)
|
Low resistance field windings of a.c. and d.c.
machines and compensating windings of d.c. machines having more than one
layer
|
R, T
|
50
|
65
|
70
|
90
|
115
|
|
|
(d)
|
Single-layer windings of a.c. and d.c. machines
with exposed bare or varnished metal surfaces and single-layer compensating
windings of d.c. machines
|
R, T
|
55
|
70
|
80
|
100
|
125
|
| 5.
|
Permanently
short-circuited insulated windings
|
T
|
50
|
65
|
70
|
90
|
115
|
| 6.
|
Permanently
short-circuited uninsulated windings
|
T
|
The temperature rise of these
parts shall in no case reach such a value that there is a risk to any
insulation or other materials on adjacent parts or to the item
itself
|
| 7.
|
Magnetic cores and
other parts not in contact with windings
|
T
|
| 8.
|
Magnetic cores and
other parts in contact with windings
|
T
|
50
|
65
|
70
|
90
|
110
|
| 9.
|
Commutators and
slip-rings open and enclosed
|
T
|
50
|
60
|
70
|
80
|
90
|
Note
1. Where water cooled heat exchangers are
used in the machine cooling circuit the temperature rises are to be
measured with respect to the temperature of the cooling water at the
inlet to the heat exchanger and the temperature rises given in this
Table shall be increased by 10°C provided the inlet water temperature
does not exceed the values given in Pt 6, Ch 2, 1.9 Ambient reference and operating conditions.
Note
2. T = thermometer
method
R = resistance method
ETD = embedded temperature detector.
Note
3. Temperature rise measurements are to
use the resistance method whenever practicable.
Note
4. The ETD method may only be used when
the ETD’s are located between coil sides in the slot.
|
9.4.4 The
transient voltage rise at the terminals of a generator is not to exceed
20 per cent of rated voltage when rated kVA at a power factor not
greater than 0,8 is thrown off.
9.4.5 Generators
and their voltage regulation systems are to be capable of maintaining,
without damage, under steady state short-circuit conditions a current
of at least three times the full load rated current for a duration
of at least two seconds or where precise data is available for the
duration of any time delay which may be provided by a tripping device
for discrimination purposes.
9.4.6 Generators
required to run in parallel are to be stable from no load (kW) up
to the total combined full load (kW) of the group, and load sharing
is to be such that the load on any generator does not normally differ
from its proportionate share of the total load by more than 15 per
cent of the rated output (kW) of the largest machine or 25 per cent
of the rated output (kW) of the individual machine, whichever is less.
9.4.7 When
generators are operated in parallel, the kVA loads of the individual
generating sets are not to differ from the proportionate share of
the total kVA load by more than 5 per cent of the rated kVA output
of the largest machines.
9.5 Overloads
9.5.1 Machines are to withstand on test, without injury, the following occasional
overloads:
-
Generators. An excess current of 50 per cent for 30 seconds after attaining
the temperature rise corresponding to rated current, the terminal voltage being
maintained as near the rated value as possible. The foregoing does not apply to
the overload torque capacity of the prime mover.
-
Motors. At
rated speed or, in the case of a range of speeds, at the highest and
lowest speeds, under gradual increase of torque, the appropriate excess
torque given below. Synchronous motors and synchronous induction motors
are required to withstand the excess torque without falling out of
synchronism and without adjustment of the excitation circuit preset
at the value corresponding to rated load:
| d.c.
motors
|
50
per cent for 15 seconds;
|
| polyphase a.c.
|
|
| synchronous motors
|
50 per
cent for 15 seconds;
|
| polyphase a.c.
|
|
| synchronous
|
|
| induction motors
|
35
per cent for 15 seconds;
|
| polyphase a.c.
|
|
| induction motors
|
60
per cent for 15 seconds.
|
-
Propulsion
machines. The overload tests for propulsion machines will be
specially considered for each installation.
-
Windlasses. For the design and testing of windlass electric motors,
see
Pt 3, Ch 13, 8 Anchor windlass design and testing.
9.6 Machine enclosure
9.6.1 Where
liquid-cooled heat exchangers are used in the machine cooling circuit
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 machine.
9.7 Direct current machines
9.7.1 The
final running position of brushgear is to be clearly and permanently
marked.
9.7.2 Direct
current machines are to work with fixed brush setting from no load
to the momentary overload specified without injurious sparking.
9.8 Survey and testing
9.8.1 On machines
for essential services tests are to be carried out and a certificate
furnished by the manufacturer. The tests are to include temperature
rise, momentary overload, high voltage, and commutation. The insulation
resistance and the temperature at which it was measured are to be
recorded, see also Pt 6, Ch 2, 1.4 Surveys 1.4.2 to Pt 6, Ch 2, 1.4 Surveys 1.4.4
9.8.2 In the
case of duplicate machines, type tests of temperature rise, excess
current and torque and commutation taken on a machine identical in
rating and in all other essential details may be accepted in conjunction
with abbreviated tests on each machine. Type tests for propulsion
machines will be specially considered, see also
Pt 6, Ch 2, 16 Electric propulsion. For the abbreviated tests,
each machine is to be run and is to be found electrically and mechanically
sound and is to have a high voltage test and insulation resistance
recorded.
9.8.3 A high
voltage test, in accordance with Pt 6, Ch 2, 21 Testing and trials, is to be applied to new machines, preferably at the conclusion
of the temperature rise test. Where both ends of each phase are brought
out to accessible separate terminals each phase is to be tested separately.
9.8.4 Survey
during manufacture, see
Pt 6, Ch 2, 1.4 Surveys,
is to be conducted prior to testing of the completed machine and is
to include inspection of rotor and stator assemblies to assess compliance
with the constructional requirements of the relevant standards and
this Section.
9.8.5 For
high voltage machines, a description of rotor and stator insulation
system application procedures (taping, impregnation, pressing and
curing, etc.) with application process records, including details
of checks and tests conducted to verify successful application, is
to be made available to the LR Surveyor during manufacture, see
also
Pt 6, Ch 2, 9.1 General requirements 9.1.15.
9.8.6 Routine
impulse tests are to be carried out on the coils of high voltage machines
in accordance with IEC 60034- 15:Rotating electrical machines
– Part 15: Impulse voltage withstand levels of form-wound stator
coils for rotating a.c. machines, in order to demonstrate a
satisfactory withstand level of the inter-turn insulation to voltage
surges. The test is to be carried out on all coils after they have
been inserted in the slots and after wedging and bracing. Each coil
shall be subjected to at least five impulses of injected voltage,
the peak value of the injected voltage being given by the formula:
where
|
V
|
= |
rated
line voltage r.m.s. |
Alternative proposals to demonstrate the withstand level of
inter-turn insulation will be considered.
|