Section 4 Rotating machines
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Inland Waterways Ships, July 2022 - Part 6 Control, Electrical and Fire - Chapter 2 Electrical Installations - Section 4 Rotating machines

Section 4 Rotating machines

Parent topic: Chapter 2 Electrical Installations

4.1 General

4.1.1 Rotating machines are to be constructed in accordance with an acceptable National or International Standard, due regard being given to the ambient conditions stated in Pt 6, Ch 2, 1.5 Ambient temperatures.

4.1.2  The entity responsible for assembling the alternating current generating set is to install a rating plate marked with at least the following information:

  1. the generating set manufacturer’s name or mark;
  2. the set serial number;
  3. the set date of manufacture (month/year);
  4. 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;
  5. the rated power factor;
  6. the set rated frequency (Hz);
  7. the set rated voltage (V);
  8. the set rated current (A); and
  9. the mass (kg).

4.2 Rating

4.2.1 Ships’ service generators, including their exciters, 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 inPt 6, Ch 2, 4.3 Temperature rise being exceeded. Other generators and motors are to be rated in accordance with the duty which they are to perform, and when tested under rated load conditions the temperature rise is not to exceed the values in Pt 6, Ch 2, 4.3 Temperature rise. Alternatively, limits of temperature rise in accordance with an acceptable National or International Standard may be applied, see Pt 6, Ch 2, 4.1 General 4.1.1.

4.3 Temperature rise

4.3.1  Table 2.4.1 Temperature rise in °C calculated on the basis of a cooling air temperature not exceeding 40°C gives the limits of temperature rise above the cooling air temperature, calculated on the basis of a cooling air temperature not exceeding 40°C.

Table 2.4.1 Temperature rise in °C calculated on the basis of a cooling air temperature not exceeding 40°C

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 60 — 85 100 120
R 55 — 75 95 115
  (b) a.c. windings of machines having output of less than 5000 kVA ETD 60 — 85 105 120
R 55 70 75 100 115
2. Windings of armatures having commutators R 55 70 75 100 120
T 45 60 65 80 100
3. Field windings of a.c. and d.c. machines having d.c. excitation other than those in item 4 R 55 70 75 100 120
T 45 60 65 80 100
4. (a) Field windings of synchronous machines with cylindrical rotors having d.c. excitation R — — 85 105 130
  (b) Stationary field windings of d.c. machines having more than one layer R 55 70 75 100 120
T 45 60 65 80 100
  (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 55 70 75 95 120
  (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 60 75 85 105 130
5. Permanently short-circuited insulated windings T 55 70 75 95 120
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 55 70 75 95 115
9. Commutators and slip-rings open and enclosed T 55 65 75 85 95

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 Table 2.4.1 Temperature rise in °C calculated on the basis of a cooling air temperature not exceeding 40°C shall be increased by 10°C provided the inlet water temperature does not exceed the values given in Pt 6, Ch 2, 1.5 Ambient temperatures.

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 ETDs are located between coil sides in the slot.

4.3.2 For machines intended to operate in ships intended for operation in tropical zones, as defined in Pt 6, Ch 2, 1.5 Ambient temperatures, the temperature rises given should be reduced by 5°C for all machines.

4.3.3 If it is known that the temperature of the cooling air exceeds the values given in Pt 6, Ch 2, 1.5 Ambient temperatures, the permissible temperature rise is to be reduced by an amount equal to the excess temperature of the cooling air.

4.4 Direct current service generators

4.4.1 Automatic voltage regulators are to be provided for shunt wound direct current generators.

4.4.2 Direct current generators used for charging batteries without series-regulating resistors are to be either:

  1. shunt-wound; or

  2. compound-wound with switches arranged so that the series winding can be switched out of service.

4.4.3 Means are to be provided at the switchboard to enable the voltage of generators required to run in parallel to be adjusted separately.

4.4.4 For each direct current generator, coupled to its prime mover, at any temperature within the working range, the means required by Pt 6, Ch 2, 4.4 Direct current service generators 4.4.3 is to be capable of adjusting the voltage at any load between no load and full load to within:

  1. 0,5 per cent of rated voltage for generators of rating exceeding 100 kW; and

  2. 1,0 per cent of rated voltage for generators of rating not exceeding 100 kW.

4.4.5 The inherent Regulation of ships’ service generators is to be such that the following conditions are satisfied:

  1. For shunt or stabilized shunt-wound generators, when the voltage has been set at full load, the steady voltage at no load shall not exceed 115 per cent of the full load value, and the voltage obtained at any intermediate value of load shall not exceed the no load value.

  2. For compound-wound generators with the generator at full load operating temperature, and starting at 20 per cent load with voltage within one per cent of rated voltage, then at full load the voltage is to be within 2,5 per cent of rated voltage. The average of the ascending and descending load/voltage curves between 20 per cent load and full load is not to vary more than four per cent from rated voltage.

4.4.6 Generators are to be capable of delivering continuously the full load current and normal rated voltage at the terminals when running at full load engine speed at all ambient temperatures up to the specified maximum.

4.4.7 Generators required to run in parallel are to be stable from no load up to the total combined load of the group, and load sharing is to be satisfactory.

4.4.8 The series winding of each two-wire generator is to be connected to the negative terminal.

4.4.9 Equalizer connections are to have a cross-sectional area appropriate to the system but in no case less than 50 per cent of that of the negative connection from the generator to the switchboard.

4.5 Alternating current service generators

4.5.1 Each alternating current service generator, unless of the self-regulating type, is to be operated in conjunction with a separate automatic voltage regulator.

4.5.2 The voltage regulation of any alternating current generator with its AVR is to be such that at all loads from zero to full load the rated voltage at rated power factor is maintained under steady conditions within ±2,5 per cent.

4.5.3 Alternating current generators required to run in parallel are to be stable from 20 per cent full load (kW) up to the total combined full load (kW) of the group, and load sharing is to be satisfactory. The facilities for adjusting the governor of an alternating current generating set, at normal frequency, are to be sufficiently fine to permit an adjustment of load on the prime mover to within five per cent of full load.

4.5.4 When generators are operated in parallel, the kVA loads of the individual generating sets are not to differ from their proportionate share of the total kVA load by more than five per cent of the rated kVA output of the largest machine when operating at 0,8 power factor.

4.6 Inspection and testing

4.6.1 On machines for essential services, tests are to be carried out in accordance with the relevant standard and a certificate furnished by the manufacturer.

4.6.2 Generators and motors of 100 kW or over intended for essential services are to be inspected by the Surveyors during manufacture and testing.

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