Sunday, December 16, 2018

Article Index

Electrical Testing by Southern Testing.

Dockside, Shipyard or at Sea, 7 day service.

Southern Testing are one of the leading In Class electrical surveyors of Oil rigs,offshore support vessels, Mega /Super Yachts and smaller vessels in Europe & the Caribbean. We regularly perform the insulation & inspection surveys required by the flag state or classification society.Our anti corrosion services are world class from our sister company

We are BOSIET & HUET accredited. 

  • Generators and control systems.
  • Current injection testing
  • Power analysis
  • IR and PI testing
  • Anti corrosion services
  • Fault finding
  • Design

 A recent survey on a vessel found this 250V DC circuit breaker still in service it was commissioned in 1930.

DC 250 volt circuit breaker

Some marine installations use the IT earthing system although it is known in the marine world as a floating neutral, we have a great deal of experience with this system both as marine and medical systems. A brief idea of the basic regs is available below.

12.1.1 Electrical installations should be such that:

.1 all electrical auxiliary services necessary for maintaining the craft in normal operation and habitable conditions will be ensured without recourse to the emergency source of electrical power;

.2 electrical services essential for safety will be ensured under various emergency conditions; and

.3 the safety of passengers, crew and craft from electrical hazards will be ensured.

The FMEA should include the electrical system, taking into account the effects of electrical failure on the systems being supplied. In cases where faults can occur without being detected during routine checks on the installations, the analysis should take into account the possibility of faults occurring simultaneously or consecutively.

Surveyors should ensure that the details and arrangements comply with the Regulations and the Code, and that workmanship is in all respects satisfactory. In addition to IEC Standards, the Regulations for the Electrical and Electronic Equipment of Ships with Recommended Practice for their Implementation published by the Institution of Electrical Engineers, may be used for guidance.

The FMEA should comply with the requirements of Annexes 3 and 4. Normally compliance will be achieved by provision of redundant systems as detailed in 4.5 of Annex 4, and numerical assessment will not be required. Consideration should be given to the independence of redundant systems as required by 4.5.2 of Annex 4. The effect of complete or partial failure of the electrical installation should be assessed against the definitions of Effects contained in 2.3 of Annex 3, taking into account craft handling under reduced propulsion and the variety of circumstances in which such failure may occur throughout the operational life of the craft. As guidance, complete failure of propulsion may result in a hazardous or catastrophic effect under adverse circumstances of weather and location, which should be given due weight in any numerical assessment of probability. It is recommended that FMEA’s should be forwarded to HQ for advice, particularly those which comply by means of numerical assessment.

12.1.2 The electrical system should be designed and installed so that the probability of the craft being at risk of failure of a service is extremely remote.
This requirement should be adequately covered within the FMEA, although the use of the term ‘extremely remote’ should not be taken in the context of numerical probabilities described in Annex 3.

12.1.3 Where loss of particular essential service would cause serious risk to the craft, the service should be fed by at least two independent circuits fed in such a way that no single failure in the electrical supply or distribution systems would affect both supplies.
Normally compliance will be achieved by provision of redundant systems as detailed in 4.5 of Annex 4.

12.1.4 The securing arrangements for heavy items, i.e. accumulator batteries, should, as far as practicable, prevent excessive movement during the accelerations due to grounding or collision.
See section 4.3.

12.1.5 Precautions should be taken to minimise risk of supplies to essential and emergency services being interrupted by the inadvertent or accidental opening of switches or circuit breakers.