Section
6 Rotating machines – general requirements and motors
6.1 General requirements
6.1.1 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, Table 3.4.1 Ambient operating
conditions in Vol 2, Pt 1 General Requirements
- 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.
6.1.3 The insulation system of electrical rotating machines used for Ship Type
and Mobility systems are to be tested following the principles detailed in IEC 60505,
Evaluation and qualification of electrical insulations systems, or an
equivalent National Standard acceptable to LR.
6.1.5 All machines of 100 kW and over, intended for Mobility or Ship Type
systems, are to be surveyed by the Surveyor during manufacture and test, see also
Vol 2, Pt 9, Ch 1, 1.6 Surveys 1.6.6.
6.1.7 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.
6.1.8 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.
6.1.9 The lubrication arrangement for bearings are to be effective under all
operating conditions including the maximum ship inclinations defined by Table 3.4.2 Inclinations, Vol 2, Pt 1, Ch 3, 4.6 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.
6.1.10 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.
6.1.11 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.
6.1.12 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.
6.1.13 The reference insulation system, against which the test samples in Vol 2, Pt 9, Ch 3, 6.1 General requirements 6.1.12 are to
be validated, is to have 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.
6.1.14 Sample coils for use in the machines detailed in Vol 2, Pt 9, Ch 3, 6.1 General
requirements 6.1.11 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 TR 60894, Guide for test procedure for the measurement of loss tangent of
coils and bars for machine windings, at ambient temperature; 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.
6.1.16 Converter-fed high voltage rotating machines intended for Ship Type and Mobility systems
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
- ault conditions.
6.1.18 The completed stator of high voltage rotating machines to be used for ship
type and mobility systems is 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.
6.1.19 For high voltage rotating machines to be used for ship type or mobility systems,
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.
6.1.20 Where the requirements of Vol 2, Pt 9, Ch 3, 6.1 General requirements 6.1.19 cannot be
achieved, a means of connecting partial discharge monitoring equipment is to be
installed. The means of connection is to enable through-life 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 Vol 2, Pt 9, Ch 3, 6.1 General requirements 6.1.21 may be
applied.
6.1.21 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 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.
6.1.23 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).
6.2 Ratings
6.2.1 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 Vol 2, Pt 9, Ch 3, 6.3 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 Vol 2, Pt 9, Ch 3, 6.3 Temperature rise
6.2.2 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.
6.2.3 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.
6.3 Temperature rise
6.3.1 The
limits of temperature rise specified in Table 3.6.1 Limits of temperature rise of
machines cooled by air, are based on the cooling air temperature and cooling
water temperature given in Table 3.4.1 Ambient operating
conditions, Vol 2, Pt 1, Ch 3, 4.5 Ambient operating conditions.
Table 3.6.1 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
R
|
55
50
|
—
—
|
75
70
|
95
90
|
115
110
|
|
|
(b)
|
a.c. windings of
machines having output of less than 5000 kVA
|
ETD
R
|
55
50
|
—
65
|
80
70
|
100
95
|
115
110
|
| 2.
|
Windings of armatures having commutators
|
R
T
|
50
40
|
65
55
|
70
60
|
95
75
|
115
95
|
| 3.
|
Field windings of a.c and d.c machines having d.c excitation
other than those in item 4
|
R
T
|
50
40
|
65
55
|
70
60
|
95
75
|
115
95
|
| 4.
|
(a)
|
Field windings of synchronous
machines with cylindrical roots having d.c. excitation
|
R
|
—
|
—
|
80
|
100
|
125
|
|
|
(b)
|
Stationary field windings of d.c.
machines having more than one layer
|
R
T
|
50
40
|
65
55
|
70
60
|
95
75
|
115
95
|
|
|
(c)
|
Low resistance field windings of
a.c. and d.c. machine 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
|
|
| 8.
|
Magnetic cores and other parts in contact with windings
|
T
|
50
|
65
|
70
|
90
|
110
|
| 9.
|
Commulators and slip-rings open and enclosed
|
T
|
50
|
60
|
70
|
80
|
90
|
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.
|
6.3.2 If it
is known that the temperature of cooling medium exceeds the values
given in Table 3.4.1 Ambient operating
conditions, Pt 1,
Ch 3, 4.5 the permissible temperature rise is to be reduced by an
amount equal to the excess temperature of the cooling medium.
6.4 Overloads
6.4.1 Motors
are to withstand on test, without injury, the following momentary
overloads:
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.
|
6.5 Machine enclosure
6.5.1 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.
6.6 Direct current machines
6.6.1 The
final running position of brushgear is to be clearly and permanently
marked.
6.6.2 Direct
current machines are to work with fixed brush setting from no load
to the momentary overload specified without injurious sparking.
6.7 Survey and testing
6.7.1 On machines for Mobility or Ship Type systems, 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
Vol 2, Pt 9, Ch 1, 1.6 Surveys 1.6.2.
6.7.2 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
Vol 2, Pt 4, Ch 5, 4 Electric propulsion systems. 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.
6.7.3 A high
voltage test, in accordance with Vol 2, Pt 9, Ch 10, 1 Functional requirements, 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.
6.7.4 Survey
during manufacture, see
Vol 2, Pt 9, Ch 1, 1.4 Documentation required for design review, 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.
6.7.5 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
Vol 2, Pt 9, Ch 3, 6.1 General requirements 6.1.6.
6.7.6 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:
V peak = 2,45V
where
|
V
|
= |
rated
line voltage r.m.s. |
Alternative proposals to demonstrate the withstand
level of interturn insulation will be considered.
|