Electronics Guide

Scope and Application

IEC 60533 applies to:

• Electrical and electronic systems on ships
• Equipment on mobile offshore units
• New installations and modifications to existing installations
• Both propulsion and non-propulsion electrical systems

The standard recognizes that ships represent a unique electromagnetic environment. The steel hull and superstructure create a conductive enclosure that can both shield against external interference and reflect internal emissions, creating complex field distributions. The standard provides requirements and guidance for achieving EMC in this environment.

Emission Requirements

IEC 60533 specifies limits for both conducted and radiated emissions:

Conducted emissions: The standard sets limits for interference currents and voltages on power supply connections and signal cables. Conducted emissions on power lines can propagate throughout the ship's electrical system, potentially affecting equipment far from the original source. The limits are specified at the terminals of equipment and apply to the frequency range from 10 kHz to 30 MHz.

Radiated emissions: Limits for radiated electromagnetic fields ensure that equipment does not generate interference that could affect radio receivers or other sensitive equipment. The measurement distance and limits depend on the equipment category and intended installation location. The standard recognizes that shipboard measurements are challenging and provides guidance on measurement methods.

Equipment is categorized based on its location and function, with different limits applying to bridge equipment, radio room equipment, and general shipboard equipment. Equipment installed near radio receiving antennas faces more stringent requirements due to the potential for direct coupling to sensitive receivers.

Immunity Requirements

Immunity requirements ensure equipment can operate in the shipboard electromagnetic environment:

Conducted immunity: Equipment must withstand conducted disturbances on power and signal connections. The test levels reflect the disturbances present on ship's power systems, including harmonics, transients, and radio frequency interference conducted on cables.

Radiated immunity: The standard specifies immunity to electromagnetic fields at levels representative of the shipboard environment. The test levels are higher than typical industrial requirements because ships contain powerful radio transmitters that can generate significant field strengths in enclosed spaces.

Electrostatic discharge: ESD immunity testing ensures equipment can withstand static discharges from personnel, which can occur particularly in low-humidity air-conditioned spaces.

Electrical fast transients: Transients from switching operations, particularly of inductive loads, can propagate through the ship's wiring. Equipment must withstand these transients without damage or malfunction.

Surge immunity: Power surges from switching events, lightning, and fault clearing can damage unprotected equipment. The standard specifies surge withstand requirements for shipboard equipment.

Installation Requirements

IEC 60533 provides extensive guidance on installation practices that affect EMC:

Cable segregation: The standard defines cable categories based on their EMC characteristics and specifies separation requirements between categories. Power cables carrying high currents or connected to switching equipment should be separated from signal cables and particularly from antenna cables.

Grounding and bonding: Proper grounding and bonding of equipment frames, cable shields, and structural elements is essential for EMC. The standard provides guidance on grounding system design and implementation.

Cable shield termination: The method of terminating cable shields significantly affects EMC performance. The standard recommends 360-degree termination at equipment enclosures and provides guidance on shield treatment at intermediate points.

Equipment location: The location of equipment affects both its emission potential and its susceptibility to interference. The standard provides guidance on locating sensitive equipment away from known interference sources.

Equipment Coverage

IEC 60945 applies to marine navigation and radiocommunication equipment including:

• Radar systems
• GPS and other satellite navigation receivers
• VHF, MF, and HF radio equipment
• AIS transponders
• Electronic chart display systems (ECDIS)
• Voyage data recorders (VDR)
• Compass systems and autopilots
• Depth sounders and speed logs

This equipment is essential for safe navigation and communication, making EMC reliability particularly important. Equipment meeting IEC 60945 carries type approval indicating compliance with international maritime requirements.

Environmental Requirements

IEC 60945 specifies comprehensive environmental requirements in addition to EMC:

The standard defines environmental conditions for exposed locations (open deck), protected locations (bridge), and controlled environments (radio room). Temperature, humidity, vibration, and other environmental parameters are specified for each location category.

Equipment must demonstrate compliance through type testing performed by recognized test laboratories. The test program covers all environmental parameters relevant to the equipment's intended installation location.

EMC Test Requirements

EMC testing under IEC 60945 includes:

Conducted emission tests: Measurement of interference current on power supply and signal cables from 10 kHz to 30 MHz. Limits depend on equipment category and intended installation.

Radiated emission tests: Measurement of electromagnetic field strength from 150 kHz to 2 GHz. The tests verify that equipment will not interfere with radio reception aboard ship.

Conducted immunity tests: Testing includes radio frequency conducted disturbances, electrical fast transients, surge, and power supply variations. Test levels are specified for the marine environment.

Radiated immunity tests: Equipment must demonstrate immunity to electromagnetic fields from 80 MHz to 6 GHz at levels up to 10 V/m, reflecting the high field strengths possible near shipboard transmitters. Equipment intended for installation near high-power transmitters may require testing at higher levels.

Special tests: For equipment with specific functions, additional EMC tests may apply. Radio receivers, for example, must demonstrate adequate selectivity and spurious response rejection.

Type Approval Process

Equipment meeting IEC 60945 requirements receives type approval:

Type testing is performed by laboratories recognized by maritime authorities. The test program covers all applicable requirements of IEC 60945 plus any equipment-specific IMO performance standards.

Successful type testing leads to certification by a flag state administration or recognized classification society. This certification is required before equipment can be installed on SOLAS vessels.

Quality assurance of production ensures that manufactured equipment matches the type-tested sample. Manufacturers must maintain production quality systems acceptable to the certifying authority.

IACS Structure and Role

IACS members include classification societies such as Lloyd's Register, DNV, Bureau Veritas, American Bureau of Shipping, and others. These societies classify ships on behalf of flag states and insurers, verifying compliance with applicable rules and regulations.

IACS Unified Requirements (UR) are mandatory requirements that all member societies must incorporate into their rules. Unified Interpretations (UI) clarify IMO requirements. Recommendations provide guidance without mandatory status.

Electrical Installation Requirements

IACS requirements for electrical installations include EMC provisions:

UR E10: Requirements for test specification for type approval of electrical and electronic equipment. This unified requirement establishes EMC test requirements for shipboard equipment, referencing IEC 60533 and IEC 60945 as applicable.

UR E22: Unified requirements for IACS procedural requirements for service suppliers. This addresses the certification of test laboratories performing EMC testing for marine equipment.

Individual classification societies may have additional requirements or interpretations of the IACS requirements. Manufacturers seeking worldwide acceptance should consider the requirements of multiple classification societies.

New Technology Provisions

IACS requirements address emerging technologies:

Unified Requirements for integrated bridge systems, dynamic positioning systems, and other complex electronic systems include EMC provisions specific to these applications.

As new technologies emerge, IACS develops appropriate requirements through its technical committee structure. The EMC requirements evolve to address new equipment types and electromagnetic phenomena.

Lloyd's Register

Lloyd's Register rules for ships include:

Part 6 Chapter 2 addresses electrical equipment, including EMC requirements. Equipment must comply with IEC 60533 or equivalent standards acceptable to Lloyd's Register.

Lloyd's Register offers notations for enhanced EMC performance, such as the "EMC" notation indicating a ship has been constructed with particular attention to electromagnetic compatibility.

Type approval of equipment by Lloyd's Register involves review of design documentation and type test reports demonstrating EMC compliance.

DNV

DNV rules include:

Part 4 Chapter 8 covers electrical installations with EMC requirements referencing IEC 60533 and IEC 60945.

DNV type approval of marine equipment includes EMC testing per applicable standards. The DNV certificate indicates the equipment meets maritime EMC requirements.

DNV guidelines provide additional guidance on EMC design and installation practices beyond the minimum requirements.

Bureau Veritas

Bureau Veritas rules include:

Part C covers machinery, electricity, and automation, including EMC requirements for electrical installations.

Bureau Veritas type approval encompasses EMC testing per IEC standards applicable to the equipment type.

Other Classification Societies

Other major classification societies including American Bureau of Shipping (ABS), ClassNK, RINA, and others maintain similar EMC requirements based on international standards. Equipment approved by one IACS member society is generally accepted by others through mutual recognition arrangements.

SOLAS Requirements

The International Convention for the Safety of Life at Sea (SOLAS) establishes minimum safety standards for ships engaged in international voyages:

SOLAS Chapter IV (Radiocommunications) requires ships to carry specified radio equipment meeting applicable IMO performance standards. This equipment must comply with IEC 60945 EMC requirements.

SOLAS Chapter V (Safety of Navigation) requires navigation equipment meeting IMO standards. These standards include EMC requirements for the specified equipment.

SOLAS regulations on electrical installations require compliance with applicable standards, which effectively incorporates IEC 60533 requirements.

IMO Performance Standards

The International Maritime Organization (IMO) adopts performance standards for marine equipment:

Each equipment type covered by SOLAS has an associated IMO performance standard specifying required functionality. These standards reference IEC 60945 or include specific EMC requirements.

Examples include IMO Resolution MSC.302(87) for ECDIS, IMO Resolution A.694(17) for navigation radar, and IMO Resolution A.824(19) for shipborne GPS receivers.

National Requirements

Individual flag states may have requirements beyond SOLAS:

Coastal states may impose additional requirements for vessels operating in their waters. These may include environmental requirements affecting EMC design choices.

Some flag states have domestic shipping requirements for vessels not engaged in international voyages. These may differ from SOLAS requirements.

Military and government vessels may be subject to different requirements based on their flag state's naval standards.

Safety Equipment EMC

SOLAS-required safety equipment must maintain functionality:

Fire detection and alarm systems must operate reliably without false alarms from electromagnetic interference. The systems must meet EMC requirements in applicable standards such as EN 54 series and marine-specific requirements.

Emergency communication equipment including GMDSS components must function under all foreseeable electromagnetic conditions.

Emergency lighting and power systems must be immune to electromagnetic disturbances that could disable them during emergencies.

Surveys and Certification

SOLAS compliance is verified through surveys:

Initial surveys verify that new construction meets all applicable requirements including EMC provisions. Equipment must have valid type approval, and installation must comply with classification society rules.

Periodic and annual surveys verify continued compliance. Equipment modifications or replacements must maintain EMC compliance.

Flag state authorities or their recognized organizations (typically classification societies) conduct surveys and issue statutory certificates.

Port State Control

Port state control inspections can identify EMC deficiencies:

Port state control officers inspect ships visiting their ports for compliance with applicable conventions including SOLAS. Deficiencies in EMC-related areas such as radio equipment malfunction could result in detention.

While port state control inspections do not typically include formal EMC testing, obvious problems with electronic equipment functionality may be identified as deficiencies requiring correction.

MIL-STD-461

MIL-STD-461 "Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment" is the primary US military EMC standard:

Emission requirements: MIL-STD-461 specifies conducted and radiated emission limits more stringent than commercial standards. The limits vary based on platform type, with shipboard requirements specified for surface ships and submarines.

Susceptibility requirements: The standard includes comprehensive immunity testing beyond typical commercial requirements, including high-level radiated susceptibility testing and spike/transient testing.

Test methods: MIL-STD-461 references MIL-STD-461G (or current version) test methods, with specific setup requirements and measurement procedures.

Equipment intended for US Navy ships must meet MIL-STD-461 requirements. The specific requirements applied depend on the equipment's intended installation location and function aboard ship.

STANAG Standards

NATO Standardization Agreements (STANAGs) establish common standards for alliance forces:

STANAG 4370 (AECTP-500): Allied Environmental Conditions and Test Publications covering EMC testing methods and requirements. This provides harmonized EMC requirements for NATO forces.

STANAG 1008: Characteristics of shipboard electrical power systems, including power quality requirements that affect EMC design.

NATO member nations typically accept equipment meeting STANAG requirements for use on their naval vessels.

DEF STAN 59-411

The UK Defence Standard for EMC addresses requirements for UK Ministry of Defence equipment:

Part 3 covers test methods similar to MIL-STD-461 but with some differences in test levels and procedures.

The standard applies to equipment intended for UK naval vessels and may be specified for export contracts.

TEMPEST Requirements

Equipment handling classified information must meet TEMPEST requirements:

TEMPEST standards specify limits on unintentional emanations that could reveal classified information. These requirements are classified and not published openly.

TEMPEST requirements typically exceed normal EMC emission limits to prevent information recovery from emanations. Equipment meeting TEMPEST requirements is certified by national security authorities.

Cargo Ship Requirements

Cargo ships from general cargo vessels to container ships share common EMC requirements:

Navigation and communication equipment must meet IEC 60945 requirements with appropriate type approval. The increasing sophistication of cargo handling equipment on container ships creates additional EMC challenges.

Cargo monitoring systems for refrigerated containers, tank sensors, and cargo securing monitoring must function reliably in the ship's electromagnetic environment.

The trend toward unmanned engine rooms increases reliance on electronic monitoring and control systems that must have appropriate EMC immunity.

Tanker Requirements

Oil tankers, chemical tankers, and gas carriers have additional requirements:

Hazardous area requirements for cargo areas add EMC considerations related to intrinsically safe equipment. The relationship between EMC and explosion protection must be carefully managed.

Cargo handling control systems must function reliably during loading and discharge operations. Any EMC-related malfunction could have serious safety and environmental consequences.

Inert gas systems and vapor control systems include electronic monitoring that must be immune to interference from the ship's equipment.

Passenger Ship Requirements

Cruise ships and ferries have requirements reflecting their passenger-carrying role:

Life-saving appliance systems including public address and general alarm must function reliably under all conditions including electromagnetic disturbances.

The concentration of passenger electronic devices (phones, laptops, tablets) creates an aggregate electromagnetic environment that ship's systems must tolerate.

Entertainment and hotel systems must not interfere with navigation and safety systems. The EMC design must accommodate the different requirements of operational and passenger service systems.

Recreational Craft Directive

In Europe, the Recreational Craft Directive (RCD) includes EMC requirements:

Yachts placed on the European market must comply with the EMC Directive through the RCD's essential requirements. Equipment must meet harmonized standards including maritime EMC standards where applicable.

The RCD applies to recreational vessels from 2.5 to 24 meters in length. The EMC requirements ensure that vessel electrical systems do not cause unacceptable interference and are adequately immune to disturbances.

Commercial Yacht Codes

Large commercial yachts may be subject to various codes:

The Large Commercial Yacht Code (LY3) and previous versions apply to commercial yachts up to 3,000 GT. These codes include EMC requirements for electrical installations referencing appropriate marine standards.

The Passenger Yacht Code applies to yachts carrying more than 12 passengers. EMC requirements reflect the safety-critical nature of passenger vessels.

NMEA Standards

The National Marine Electronics Association (NMEA) develops standards for marine electronics:

NMEA 0183 and NMEA 2000 are communication protocols for marine electronics data exchange. Equipment certified to these standards must meet specified EMC requirements.

NMEA certification indicates equipment compatibility with other NMEA-certified devices, which includes EMC performance to support reliable data communication.

Testing Requirements

EMC testing for marine equipment requires appropriate facilities:

Test laboratories performing type approval testing must be recognized by the certifying authority. This typically requires accreditation to ISO/IEC 17025 and specific recognition by flag state administrations or classification societies.

Test facilities must include appropriate chambers, equipment, and expertise for marine EMC testing. The specific tests required depend on the equipment type and applicable standards.

Test reports must document full compliance with applicable requirements. Any deviations or alternative methods must be justified and accepted by the certifying authority.

Type Approval Process

Type approval demonstrates equipment compliance with applicable standards:

The manufacturer submits design documentation and test reports to the certifying authority. Review confirms that the equipment design and test results meet all applicable requirements.

Successful review results in a type approval certificate specifying the equipment model, applicable standards, and any conditions or limitations.

Type approval typically remains valid as long as the equipment design is unchanged. Modifications require assessment and may require additional testing or new type approval.

Installation Verification

Type-approved equipment must be properly installed:

Classification society surveyors verify that equipment installation complies with applicable rules and manufacturer's instructions. EMC-relevant installation aspects include cable routing, grounding, and equipment location.

Commissioning tests may include functional verification that could identify EMC problems. Systems that malfunction due to interference would require correction before the vessel enters service.