Industrial Connector

What sets an industrial connector apart

A connector is a place where two cables meet, and every such place is a potential failure point. Domestic and office connectors are made for clean, dry rooms. An industrial connector for shipboard use must keep its contact resistance steady in vibration, resist salt-laden air and moisture, survive many mating cycles and, in some applications, stay safe in an explosive atmosphere. It also saves time: with the right connector, a motor, sensor or panel can be disconnected and replaced without rewiring, which is important for equipment that is taken ashore for repair. The wide variety of series and the interchangeability of contacts and housings make correct selection a task in itself.

Main designs

• Heavy-duty multi-pole connectors, with inserts for power and signal contacts mounted in hoods and housings
• Round connectors with threaded or bayonet coupling, common on sensors, instruments and compact equipment
• Explosion-protected connectors and receptacles for hazardous areas, certified for the zone and gas group
• Network connectors, such as Category 6A types, for Ethernet connections in harsh surroundings
• Hermetic receptacles, which seal a bulkhead or enclosure entry against gas or pressure
• Modular systems that combine power, signal, data and compressed-air contacts in one housing

Main components

• Insert with the contact carrier, available with crimp, screw or spring-clamp terminals
• Contacts, in gold or silver plating for signals and heavier plating for power
• Hood and housing, in metal or plastic, with a cable gland or cable entry of the right size
• Seals that give the stated protection when the connector is mated and when it is closed with a cover
• Locking mechanism, such as a lever, a bolt or a coupling ring, which prevents the connector from coming apart in vibration

Selection and sizing

• Number of contacts, current and voltage per contact, as defined for the application
• Degree of protection when mated, for example for wet or washdown conditions, see IEC 60529
• Housing material and finish for the corrosion exposure, including stainless steel or coated aluminium where needed
• Termination type and the cable range, so cable diameter and conductor size match the connector
• Hazardous-area certification where the connector sits in a classified zone
• Compatibility between insert, hood and mating half, since parts of the same family are not always interchangeable

Regulations and class

Connectors in essential electrical circuits fall under the shipboard installation rules and class approval. Product standards such as IEC 61984 deal with the safety of connectors, and the IEC 60092 series covers the installation of electrical equipment on ships. Connectors for explosive atmospheres need a certificate under IECEx or ATEX schemes, and the marking has to match the zone and gas group in the hazardous-area plan. Type approval lists the connector series and the allowed combinations.

Typical faults

• Corrosion of contacts and housings in moist or salty surroundings, which raises contact resistance
• Water entering through damaged seals, a missing cover or a loose cable gland
• Poor crimps or loose screw terminals, which lead to heating and, in time, melted inserts
• Cable strain reaching the contacts because the strain relief was not fitted properly
• Broken or bent contacts from forced mating of the wrong or misaligned halves
• Coupling rings or locking levers not fully engaged, so the connection comes loose in vibration

What to look for in a supplier

• A type-approval certificate that names the connector series and the combinations of insert and housing
• Full range of accessories: hoods, glands, covers, seals and coding or locking parts
• Crimp tools and positioner dies matched to the contacts, with instructions for correct termination
• For explosion-protected connectors, the certificate with full marking and the installation instructions
• Stable supply and compatibility within the family, so later repairs and extensions are possible

Use the crimp tool and settings specified by the manufacturer, and pull-test a sample crimp before wiring a whole connector. A cheap general-purpose tool produces connections that look fine and fail at sea.