Transport Publication TP 127 E
27.1 Subject to subsection 27.2, tests for following electrical equipment shall be witnessed by a marine surveyor at the manufacturer’s plant, except that a recognized Classification Society Certificate shall serve as test verification of such inspection for equipment manufactured outside of Canada:
- ship’s service and emergency generators, l00 kW and over;
- propulsion generators, motors and excitation sets;
- electric motors for essential services, l00 kW and over;
- main switchboards with an aggregate connected load of 25 kW and above;
- motor control centres having a capacity of l00 kW and over;
- propulsion control switchboards;
- main propulsion cables;
- power and lighting transformers, l0 kVA and over;
- all static power supplies for emergency use; and
- all static power supplies 50 kW and over;
- all emergency switchboards.
27.2 In the case of duplicate machines, or transformers, other than propulsion machines or propulsion transformers, type tests of temperature rise and commutation taken on a prototype machine satisfy the requirements for individual testing provided they are in conjunction with a running test, high potential and insulation resistance tests.
27.3 Machines and equipment having a capacity less than that set forth in subsection (1), shall be tested by the manufacturer whose certificate of test shall be made available, if requested, to the marine surveyor.
27.4 In the case of propulsion machines operating at more than one voltage or one frequency, the predominant operating criteria shall be used as the basis for testing the machine.
28. Testing Rotating Machines
28.1 The tests which shall be carried out on the rotating machines described in Section 27 are:
- temperature-rise test;
- insulation resistance test;
- high potential test;
- overload test; and
- commutation test.
28.2 After the machines have been run continuously under full load until steady final temperatures have been reached, the temperature rises shall not exceed those given in Table 16-1,16-2 and 16-3 in Section 16.
28.3 The insulation resistance test of generator and motor windings shall be carried out with the machine at operating temperature and should be not less than one megohm.
28.4 The high potential test of ac generators shall be performed by the continuous application of an ac potential of twice the rated voltage of the machine plus 1000 volts for one minute between all windings and ground and between phases except that this test does not apply to field windings; for high voltage machines designed to operate with the neutral insulated, the test voltage shall be not less than 7.5 times the line to neutral voltage.
28.5 The high potential test of field windings of ac generators shall be performed by the continuous application of an ac potential of ten times the excitation voltage, but in no case less than 1500 volts between field brush rigging and ground, and between field brush rigging of opposite polarity.
28.6 The high potential test of dc generators shall be performed by the continuous application of an ac potential of twice the rated voltage of the machine plus 1000 volts for one minute between:
- all circuits and ground;
- shunt winding and other windings;
- brush rings of opposite polarity; and
- armature windings of generators, if provided with two commutators.
28.7 The commutation test on dc generators shall consist of the application of a momentary current of 50% in excess of rated current for 15 seconds and as near as possible to the rated voltage, without injurious sparking or injury to the commutator or brushes.
28.8 The commutation test on dc motors shall consist of the application of a momentary torque of 50% in excess of that corresponding to its rating, for 15 seconds with fixed brush setting, without injurious sparking or injury to the commutator or brushes.
28.9 The commutation of ac commutator motors shall be practically sparkless over the specified range of load and speed.
28.10 The overload test for generators shall be performed as an excess current of 50 percent for 15 seconds after attaining the temperature rise corresponding to rated load, 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.
28.11 The overload test for motors shall be performed 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 excitation circuit preset at the value corresponding to rated load:
28.12 Ships’ service generators are to be capable of withstanding the mechanical and thermal effects of fault current for the duration of any time delay which may be fitted in a tripping device for discrimination purposes; they are to be capable of maintaining under steady-state short-circuit conditions a current of at least 3 times the full load for a duration of 2 seconds or, where precise data is available, for the duration of any time delay which may be fitted in a tripping device for discrimination purposes.
29. Testing Switchboards and Motor Control Centres
29.1 The following tests shall be carried out on those main, emergency and propulsion switchboards and motor control centres required to be tested:
- satisfactory operation of overload protective devices for ship’s service and emergency generators;
- high potential test; and
- insulation resistance test.
29.2 The satisfactory operation of the overload protective devices for generators shall be performed by passing the full value of the necessary current to actuate the tripping devices by the technique of primary injection or other means; settings for the long time trips, short time trips and instantaneous trips, where fitted, are to be posted near or within the switchboard(s).
29.3 The high potential test for all switching and control apparatus for systems over 60 volts should be twice the rated volts plus 1000 volts for one minute.
29.4 The insulation resistance shall be not less than 1 megohm between:
- all current-carrying parts connected and ground; and
- current-carrying parts of opposite polarity or phase.
30. Testing Main Propulsion Cables
30.1 All main cables for electric propelling machinery shall be tested in accordance with the following:
- the high potential test shall be carried out on finished cables with either a single-phase ac voltage or a dc voltage , and the power available in the test equipment shall be sufficient to maintain constantly in the cable the specified value of the test voltage and the corresponding charging current;
- the test voltage shall be applied gradually to the cable so as to arrive at the specified value in about one minute;
- the test voltage for single-core, metal sheathed or metal armoured cables shall be applied between conductor and sheath or armour;
- the test voltage for single-core cables having an impervious non-metallic sheath and no further covering shall be applied between the conductor and the water, and the cable shall be immersed for at least one hour before the test;
- in the case of single-core cables having a non-metallic covering liable to be impaired if immersed in water, the test voltage shall be made on samples at least 1.02 m long, after having covered their surface with a metal foil;
- whichever the insulation type, each insulated core shall sustain for five minutes, without breakdown occurring, the values given in Table 30-1;
Rated Voltage of Cable Testing Voltage for 5 minutes Volts ( ac or dc ) Volts ac Volts dc - 250 1500 3000 250 750 2500 5000 750 1100 3000 6000 1100 3300 10000 20000 3300 6600 16000 32000 - immediately after the high potential test has been carried out, the insulation resistance shall be measured with a dc voltage of at least 300 volts using the same connections and procedures set forth in paragraphs (c), (d) and (e); and
- the measurement of the insulation resistance shall be effected within one minute after application of the dc voltage provided that in certain cases, in order to reach a substantial steady state condition, the electrification time be prolonged up to a maximum of 5 minutes.
31. Testing Transformers for Lighting and Power
31.1 A high-potential test shall be carried out on every transformer described in Section 27 preferably with the transformer hot, immediately after the temperature rise test; the test shall be applied between the winding under test and the remaining windings, frame and tank of the transformer all connected to ground.
31.2 The test shall be made with
ac
at a convenient frequency between 25
Hz
and twice the rated frequency and the full test voltage, as shown in Table below, and shall be maintained for one (1) minute without breakdown. Nominal Transformer Voltage: 1200 or less
Applied Voltage: 4
kV
Nominal Transformer Voltage: 2400
Applied Voltage: 10
kV
Nominal Transformer Voltage: 4160
Applied Voltage: 12
kV
31.3 Induced potential: an ac potential of twice the maximum rated voltage of one winding at a suitable frequency shall be applied for a duration equal to
1 min. X Twice rated Frequency
Test Frequency
with a minimum of 15 seconds between the terminals of that winding with the ends of the other windings open.
31.4 Temperature rise: rated voltage at rated frequency shall be applied to the primary windings of a transformer with rated load connected to the secondary windings; as an alternative, tests resulting in losses approximating those obtained under normal or specified load conditions may be applied; the test shall be continued until constant temperatures are attained; the temperature rises shall not exceed those given in Table 14-1.
31.5 Insulation resistance test of the transformer windings shall be carried out, preferably with the transformer winding hot, immediately after the temperature rise test and shall be not less than one megohm.
32. Testing Static Power Supplies
32.1 A high-potential test shall be carried out on every static power supply described in section 27, preferably with the unit hot, immediately after the temperature rise test; the test shall be made with ac of suitable frequency and applied for a period of one minute, both between parts connected to different circuits (where applicable) and between live parts and exposed non-current-carrying metal parts as follows:
- rms voltage determined by the formula:
2 X Up + 1000 V
√2
with a minimum of 2000 V , where Up is the peak value of the highest voltage (transient over-voltage excluded) which occurs within the equipment in rated service. - where Up/√2 is not higher than 60 volts, the ac test voltage shall be 600 volts rms; and
- where Up/√2 is in the range of 60 to 90 volts, the ac test voltage shall be 900 volts rms
32.2 Temperature rise: Rated voltage at rated frequency shall be applied to the input side of the static power supply with rated load connected to the output side; the test shall be continued until constant temperatures are attained.
32.3 Overload test: The static power supply unit shall be tested to ensure that the internal protective devices integral with the unit will function and protect the unit in accordance with the manufacturer’s damage curve.
32.4 If a cooling fan is provided, the fire hazard due to fan failure shall be investigated.
32.5 Insulation resistance test of the wiring of the static power supply shall be carried out, preferably with the unit hot, immediately after the temperature rise test and the resistance shall be not less than one megohm.