Industry 4.0, and the gradual transformation of the factory floor into a smart automation system, involves an increasing number of electrical applications working in unison. These naturally need to be joined to each other to make a unified whole, and this is where choosing the correct connectors can be your most important design decision.

A myriad of modern devices such as switches, sensors, valves, actuators, conveyors and cameras are all used to carry out production, control and monitoring processes, for which they require secure signal connections. Such devices combine a broad spectrum of functions, and need to include features ensuring accuracy and reliability as well as safety and cost efficient operation.

With input flowing into an automated industry from such a wide variety of sources, ethernet and profibus connectors are an increasingly common component, and are acquiring additional functionalities. This means that your control system not only receives information in a constant flow of data, but can also process it and forward it on to other systems. Dataflow connectors can be used for many different advanced applications, including surge protection, energy measurement and machinery identification, improving your system's overall safety and reliability.

Choosing the correct connector is bound to be influenced by the environment in which your device is operating, and whether external elements could affect signal reliability. Such elements can include hazardous environments such as explosive or mining areas, radiation labs, underwater treatment plants, extremes of temperature and chemical contaminants, as well as everyday hazards such as damp, dirt, oils and UV exposure.

Harting Connectors offer dedicated design ranges for specific environments, so that you can tailor your needs to cover all eventualities and ensure reliable and safe signal connections. Corrosion resistant hoods and housings can be supplied with cable entry protection and stainless steel locking levers for extreme conditions, while pure stainless steel inox versions are supplied especially for the food and beverage industry, where the utmost cleanliness is essential. You can choose higher EMC protection for sensitive electromagnetic interconnections, or lightweight models made from polyamide reinforced with glass fibre, for a more eco-friendly solution.

In heavy industrial applications there is the additional risk of excess vibration and mechanical shock, which can cause disturbances in the connector components and result in partial or complete loss of signal. When choosing the correct connector for this kind of application, it is therefore necessary to consider elements that are resistant to vibration, such as mechanical latches, mounting flanges, locking screw threads or set screws, radial O-rings and spring technology. Furthermore, your device might experience EMI (electromechanical interference) from other equipment located nearby, which might cause unreliable signal transmission or complete signal loss. In this event you should choose an end-to-end system of cabling and connectors that will shield the signal and eliminate any possibility of EMI.

Industrial connectors don't usually cater for high-frequency signals, and are designed instead for signal frequencies most commonly used in mainstream industrial processes. Most connectors are therefore rated for 600V, although special models can be designed to handle higher voltages of up to 5kV or conductors that can carry hundreds of amps. Combined system modules can also include air connections, incorporating connectors that can handle air pressures up to 116 psi through a ¼" diameter hose.

Every application in your automated system will require a reliable connection, to ensure that signal integrity is not compromised by interruptions at any point in the line. The wire terminals are the most vulnerable point where they attach to the contact, but the material quality of the contact is also a crucial factor that can significantly affect its performance. Many metals corrode on exposure to air, and a poor quality contact will be subject to fretting and oxidisation. For this reason, the best quality connectors are constructed with gold, which is non-corrosive and provides good electrical conduction.

Gold-plated connectors may sound like an ostentatious and inefficient use of resources, but a better quality connector will last longer than a cheaper variety. Costs must inevitably be taken into account when choosing the correct industrial connector, but cost efficiency must span the entire automation process, from procurement to installation and maintenance. A better quality component with faster installation, such as a modular snap-on rail construction, will reduce overall equipment downtime and associated labour costs for installation or repairs. Long-term benefits should always be factored in and valued against short-term gains from cheaper components.

A modular connector can combine power, data and signal inputs in a single connection, thus saving considerably on space and wiring complexity. Modules can also accommodate non-electrical inputs, such as fibre optics or compressed air lines, in the same device. Modular snap-on connectors are also much quicker for device installation, especially if an application requires multiple connections. IDC (insulation displacement contacts) terminations, spring contact terminals and push-in contacts are all ideal varieties of contact for making speedy and efficient connections, or quick plugs installed with a half-turn.

Poorly lit or hard to reach conditions can lead to human installation errors such as cross threading or finger fatigue, which makes older-style connectors a less cost-efficient choice. Using HMI (human-machine interface) technology, systems can now be more efficiently designed with faster connections using rail-mounted plug and play connectors, which cuts down on overall installation time – as much as 80% using spring-contact connectors and 60% with IDC connectors. Other human connection errors can be reduced, such as mismating, or plugging a connector into the wrong socket.

In keeping with the general trend of mechanical evolution, size reduction continues to be an important factor, and most modular connectors are found within a range of 3-6" x 2". The ability to construct smaller and smaller components and to increase connector pin counts has also led to a general trend for higher density products in a more compact unit. Most contemporary connectors are therefore now designed in a module that combines functionality with flexibility, saving both on space and installation time. A modular connector could physically accommodate up to 300 wires of 24AWG gauge, or 216 wires of 14AWG, but this is an exceedingly rare occurrence. Most applications will be using connectors handling from 4-50 connections for electrical conductors of 22WG or larger, and this can lead to some potential for mismated connectors.

To avoid this problem, design engineers using a signal connectivity interface can choose circular connectors that employ coded keying patterns. This will eliminate confusion when multiple connectors coded with the same landing footprint are being installed in a single device. A signal connectivity design scheme might include circular connectors that have alphabetical keying variations, such as X or Y, S or T and A, B, C. Different keying patterns can also be used in terminal block connectors to make sure that only the right plug is mated with the right socket, and some schemes employ colour coding as a simplified form of identification.

Design engineers will have to take into consideration every aspect of the automation system when choosing the correct connectors, including such factors as the environment where the connectors are installed, what method of installation is used, and appropriate safety requirements. Additional factors such as the density of the connector assembly and maintaining signal integrity will have to be reviewed, but whatever your automation system requires, there'll be a connector just right for the job.