Section 7 Electrical Pressure Hull Penetrators and Cable Connectors
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Clasifications Register Rules and Regulations - Rules and Regulations for the Construction & Classification of Submersibles & Diving Systems, July 2022 - Part 6 Electrical Installations and Control Engineering Systems - Chapter 1 Electrical Installations - Section 7 Electrical Pressure Hull Penetrators and Cable Connectors

Section 7 Electrical Pressure Hull Penetrators and Cable Connectors

Parent topic: Chapter 1 Electrical Installations

7.1 General

7.1.1 Electrical penetrators are to be arranged separately from other penetrators, they are not to impair the gas/watertight integrity of pressure vessels associated with diving systems and submersibles, even if the connecting cables become damaged.

7.1.2 Penetrator inserts and cable connecting pins should be secured so as to withstand damage from an accidental tensile load being imposed on the electrical cable. In addition a means of preventing undue stress on the cable/penetrator connection is to be provided.

7.1.3 All electrical penetrations in compression chamber walls and all plug connections are to be subjected to individual inspection by the manufacturer. A Works Test Certificate is to be issued by the manufacturer in respect of this inspection.

7.1.4 Penetrators are to be selected from LR’s List of Type Approved Equipment. Alternatively, type approval certification from another IACS authority, along with full test details are to be submitted for approval.

7.1.5 Positive and negative conductors from the main and auxiliary power sources are not to pass through the same penetrator or connection in a pressure boundary and are to be spaced to prevent damaging currents. All power leads passing through a pressure boundary are to be adequately protected by circuit breakers or fuses against overload and short circuit. The circuit breakers or fuses are to be located on the power source side of the pressure boundary and are to have the ability to open the circuit quickly to prevent damage to the watertight integrity of the electrical penetration. Tests may be required to demonstrate the ability of the device to perform as mentioned above.

7.1.6 Penetrators in pressure vessels associated with diving systems must be gas and watertight. Their tightness must be guaranteed even if the connected cables are damaged or torn off.

7.2 Routine tests — Penetrators

7.2.1 All electrical penetrators are to be subjected to routine tests, which are to include the requirements of Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.2 to Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.10. The test sequences for routine tests (also for type tests) are detailed in Pt 6, Ch 1, 7.4 Test sequence — Penetrators.

7.2.2 With the ‘gas’ side of the penetrator open-ended a helium atmosphere test sequence at not less than twice the working pressure, with a minimum of 6,9 N/mm2, is to be applied to it. No leakage is permitted. (See Pt 6, Ch 1, 7.4 Test sequence — Penetrators 7.4.1 f) and g)).

7.2.3 A hydrostatic pressure test sequence at not less than twice the operating pressure is to be applied to the ‘wet’ side of the penetrator. No leakage is permitted. See Pt 6, Ch 1, 7.4 Test sequence — Penetrators 7.4.1b).

7.2.4 Compression chamber wall penetrators and underwater plug connections must have been type tested in accordance with Pt 6, Ch 1, 7.3 Type tests — Penetrators and Pt 6, Ch 1, 7.4 Test sequence — Penetrators or an equivalent set of tests from another IACS authority.

7.2.5 High-voltage test (Dielectric Test) at an a.c. voltage of 1 kV plus twice the rated voltage. This test is performed at the rated frequency and is to be carried out for 1 minute in each case between all the conductors mutually and between the conductors and the casing. The test is performed in the disconnected state. The connection side of the compression chamber wall penetration may be fully wired for the high-voltage test. The sealing of the connector shells and the like is permitted where this is stipulated by the manufacturer in the relevant data sheet.

7.2.6 The test voltage for plug connections rated at more than 500 V is to be agreed with LR.

7.2.7 The insulation resistance is to be measured with an instrument using 500 V d.c. With wet plug connections, the minimum insulation resistance is also to be measured after the connection has been made once in salt water – check against manufacturer's documentation.

7.2.8 All conductors are to be subject to a high voltage test, before the release of the hydrostatic pressure on the final pressure cycle, of 1 kV a.c. plus twice the rated voltage (see Note) for one minute between each conductor separately and the remaining conductors together with any screen connected to the penetrator body and earth. No breakdown is permitted.
Note If no conductor is to be operated at a voltage above 60 V a.c. or 75 V d.c. the test can be carried out at 500 V a.c.

7.2.9 On completion of the tests the insulation resistance is to be measured at a voltage of at least 500 V d.c. and a resistance between conductors and between each conductor and earth of at least 5 MΩ recorded.

7.2.10 For plug and socket type penetrators continuity across the contacts is to be measured.
Note If only one side of a penetrator is to be subjected to pressure, the hydrostatic and Helium pressure tests referenced above need only be carried out on that side.

7.3 Type tests — Penetrators

7.3.1 For the purpose of type testing a program is to be submitted for consideration: The following areas should be covered:
  1. The routine tests given in Pt 6, Ch 1, 7.2 Routine tests — Penetrators;
  2. Temperature rise of contacts and blocking inserts;
  3. Tracking index of insulating material of blocking inserts;
  4. Pressure tests at not less than twice the working pressure, in a cyclical manner, on both the ‘gas’ and ‘wet’ side of the penetrator, followed by a temperature cycle test, and a repeat of the pressure test. (See Pt 6, Ch 1, 7.4 Test sequence — Penetratorsa) and c));
  5. Test showing the effects of simulated rupture of the connecting cable.

7.4 Test sequence — Penetrators

7.4.1 Hydrostatic pressure and temperature tests should consist of a sequence of cycles. As an example, the following would be acceptable:
  1. Pressure test sequence — Type tests;
    1. Conduct electrical tests as detailed in Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.5 through to Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.10;
    2. Pressurize — hold for 24 hours — release to 10% of test pressure and hold for 15 minutes then reduce to zero;
    3. Pressurize — hold for 15 minutes — release to zero;
    4. Pressurize — hold for 3 minutes — release to zero;
    5. Pressurize — hold for 3 minutes — release to zero;
    6. Pressurize — hold for 3 minutes — release to zero;
    7. Pressurize — hold for 15 minutes — release to zero. Repeat electrical insulation tests as detailed in Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.5 through to Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.10– release to zero.
  2. Hydrostatic pressure test sequences — Routine tests;
    1. Pressurize — hold for 15 minutes — release to zero;
    2. Pressurize hold for 3 minutes — release to zero;
    3. Conduct electrical tests as detailed in Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.5 through to Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.10 at end of test sequence;
  3. Temperature test sequence - – Type tests;
    1. Minus 40°C for 4 hours followed by +60°C for 4 hours, the penetrator being allowed to attain ambient temperature between cycles. Repeated 3 times. On completion of the cycling temperature tests the electrical tests as detailed in Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.5 through to Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.10 are to be repeated;
  4. X-Ray test Sequence – Type Tests;
    1. Each penetrator subjected to the above tests must be X-rayed at an accredited NDT test house before and after those tests;
  5. Destructive test sequences – Type tests;
    1. The outboard cable of each penetrator that has undergone the above tests to be cut leaving a stub approximate length 150mm;
    2. Pressurize the penetrator under hydrostatic conditions, as in a) ii above, hold for 24 hours, release to zero;
    3. Check for barrier leakage during and at completion of the 24 hour test. Leakage may be detected by applying absorbent tissue paper to the inboard side of the penetrator;
  6. Helium Pressure Test – Both a Type Test and a Routine Test;
  7. The penetrator shall be tested using a helium atmosphere; the pressure shall be not less than twice the working pressure and held for a period of not less than 30 minutes. A "Helium Gas Detector" shall be used to detect any leakage. A constant helium leakage reading in the 10-5 (ten to the power minus 5) range on the Helium Gas Detector, specifically 5 parts per million, is acceptable as this matches the typical Helium content of atmospheric air. The High Voltage test as prescribed in Pt 6, Ch 1, 7.2 Routine tests — Penetrators 7.2.5 shall be carried out during the pressure hold;
  8. All conductors are to be subject to a high voltage test, before the release of the hydrostatic pressure on the final pressure cycle, of 1 kV a.c. plus twice the rated voltage (see Note) for one minute between each conductor separately and the remaining conductors together with any screen connected to the penetrator body and earth. No breakdown is permitted.
Note If no conductor is to be operated at a voltage above 60 V a.c. or 75 V d.c. the test can be carried out at 500 V a.c.

7.5 Routine tests — Cable connectors

7.5.1 A sample is to be pressure tested at not less than twice the working pressure. No leakage is permitted.

7.5.2 Connectors are to be subjected to a high voltage test of 1 kV a.c. plus twice the rated voltage (see Note) for one minute between each conductor separately and the remaining conductor, together with any screen connected to the connector body and earth.
Note If no conductor is to be operated at a voltage above 60 V a.c. or 75 V d.c., the test can be carried out at 500 V a.c.

7.5.3 The insulation resistance is to be measured to a voltage of at least 500 V d.c. and resistance between conductors and between each conductor and earth of at least 5 MΩ recorded.

7.5.4 Electrical continuity across the contacts is to be measured.

7.6 Type tests — Cable connectors

7.6.1 For the purpose of type testing a program is to be submitted for consideration. The following areas should be covered:
  1. The routine tests given in Pt 6, Ch 1, 7.5 Routine tests — Cable connectors;
  2. Temperature rise of contacts;
  3. Tracking index of insulating materials.
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