There are a variety of connectors used in industrial applications that feed power, sensor signals and control data on cables into and out of automation components through their connection points. Heavy-duty connectors are sometimes abbreviated as HDC in the connector product name, and their composition depends on the specific application… So sometimes it is relative. That said, there is a clear distinction between ruggedized, durable industrial connectors and those light-duty RJ and IEC connectors used in clean room automation applications that contain basic Ethernet and light-duty power.
Heavy-duty connectors can have greater overall ruggedness, as well as greater intrusion protection, lower flammability, a very wide operating temperature range, interlocking, ground shielding, or simply more reliable connections and stronger connections.
Heavy Duty Cable Sealing Sleeves and Connectors
Cable seals (sometimes called crimpers) are mostly mechanical components. They wrap around the cable as it passes through the boundaries of industrial control panels and other enclosures made of sheet metal and hard plastic, connectors and controller bodies. Cable seals serve three purposes. The specific roles are as follows.
Secure the cable
Prevents scratching and other abrasion of the cable
Forms a seal around the cable to prevent moisture from entering and siphoning into the housing
Cable sealing sleeves are used to secure the cable in a way that prevents damage to the electrical contacts if the cable is pulled or otherwise disturbed. The cable sealing sleeve also prevents the cable sheath from rubbing against sharp hole edges in the housing, as the sealing sleeve itself fills and flares out at these edges. Without a cable sealing jacket, even the slightest movement of the cable can be quickly cut by the sharp edges of the openings in the housing until its outer insulation is completely sawn away. . This eventually leads to a short circuit in the cable core.
In contrast to these cable sealing sleeves (which surround the cable), connectors are used to terminate the cable – often making it easier to disconnect and reconnect the cable, as well as to connect multiple components and cables. Typically, heavy-duty versions of such connectors include one or more reinforcement features.
Heavy-duty cable connectors can use universal cable sealing sleeves, cable clamps or sealing and anti-twist devices to provide cable entry protection. Regardless of mechanical form, these devices hold the cable in place and prevent it from being pulled out of the terminal. The cable entry protection also protects the cable from wear and tear in the same way as a separate cable sealing sleeve. Note that tab inserts (connectors with multiple finger contacts) are common on moderately ruggedized connectors, although the inserts need to be retightened periodically to ensure entry protection. For heavy-duty applications, sealing sleeves that provide a continuous seal and clamp the cable are a more reliable and common choice.
Protective covers on some heavy-duty cable connectors will surround the conductive body of the plug, providing both insulation and ingress protection – and there are also locking or latching sleeves or levers to keep the two parts of the connector together.
On many heavy-duty cable connectors, the male insert includes the male pin and a screw or crimp terminal for the portion of the conductive core that contacts the pin. On such connectors, the female insert includes the complementary jack and a socket or crimp terminal for the portion of the conductive core in contact with the jack.
The rugged housing of a heavy-duty cable connector may be its most conspicuous feature – often including insulation and intrusion protection features. Its accessories may include additional protective covers and pin code guides.
Figure : Han® series connectors have several complementary features that allow them to adapt to quite brutal environmental conditions.
IP Codes for Ingress Protection of Heavy Duty Connectors
Protection against the ingress of liquids and solid particles is also very standard for heavy-duty connectors. The intrusion protection of connectors is rated using the same Ingress Protection (IP) code as the housing. the first digit of the IP code indicates protection against solids and ranges from 0 (for no protection) to 6 – for full dust protection. the second digit of the IP code indicates protection against liquids and ranges from 0 (no protection) to 8 (continuous water resistance at a depth of 1 meter) or even 9K – for high pressure jets. The second digit of the IP code indicates protection against liquids, ranging from 0 (no protection) to 8 (continuous protection against water at a depth of 1 meter) or even 9K – for protection against high-pressure jet streams. For example, IP67-rated connectors are resistant to dust ingress and temporary immersion in water.
Proprietary connector variants – why are they so common?
Because of the strong reliance on mechanical closures and sealing features for heavy-duty connectors, many options on the market today are either proprietary designs or application-specific connector variants. For example, the HarTIng Hank series of heavy-duty rectangular connectors is used throughout the industry for power and control connections. In fact, this trademarked connector brand is sometimes considered to be synonymous with heavy-duty connectors in general.
The Han Series connectors (available in 4 and 26 pins) have become somewhat of an industry standard – meeting a wide range of data and power connection requirements from 50V to 5000V and 3 A to 200A. Locking options include a single-lever Han-Easy lock for easy one-handed operation, and a more reliable, tighter locking, double-lever Han-Easy lock for cable-to-cable connections. Yet another reinforcement option is screw locking, a locking method that allows for maximum tightness and less risk of human unlocking.
The pins of Han series connectors are arranged in a rectangular shroud that matches the corresponding sockets in the rectangular housing. The connectors are usually equipped with locking levers that allow the installer to easily and reliably close the connector: – to ensure that it cannot be pulled apart… This is true even when considerable forces are applied.
Shrouds (bolt-on connector housings) are most commonly found in power cable terminations and are available in top-entry and side-entry configurations. Housings can be threaded, surface-mounted, or through-plate mounted for easy connection at the meter or machine. Alternatively, the housing can be terminated for connection between cables. Shrouds and housings are typically manufactured from die-cast alloys. However, stainless steel and plastic housings are also common. Some manufacturers offer configurable connectors that can be connected inside the outer shroud or housing. This allows for a larger pin count for all the different modules. Such connectors are available such as Molex’s GWconnect HDC and TE ConnecTIvity HDC brand products.
Ruggedized cable connectors for data and sensor signal cables will be slightly different. Here, the M Series connectors are a distant second. This series of connectors is rugged and can be used for power transmission and a variety of data connections, including Ethernet-based connections. Ruggedized M-Series connectors are most commonly used in industrial networking applications involving PROFINET, fieldbus and industrial Ethernet for connecting sensors, switches and PLCs.
The M Series connectors consist of round male and female connectors with standard metric threaded bushings that wrap and protect the internal pins and sockets. Standard sizes include 5 mm M5, 8 mm M8, 12 mm M12, 16 mm M16, and 23 mm M23 connectors. The threaded sleeve makes for a very strong, reliable connection that cannot be easily pulled apart and ensures a very reliable electrical connection, minimizing signal discontinuity. The bushing also allows the M series connectors to achieve a high level of intrusion protection, in many cases even in environments subject to scouring and corrosion. The most common sizes are the M8 and M12 connectors, available in 2, 3, 4, 5, 8 or 12-pin versions. Typically, the 3 or 4-pin M-Series connectors are used for sensors and power supplies; the 4 or 8-pin M-Series connectors are used for Ethernet and PROFINET devices; and the 4 or 5-pin M-Series connectors are used for fieldbus, CAN bus, and DeviceNet automation devices.
Data connections used in industrial applications include Ethernet, ModbusTCP/IP, EtherCAT, Ethernet/IP, and Profinet. As well as various proprietary forms. RJ connectors are the standard for all Ethernet implementations – but are not intrusion-protected and not parti
cularly robust. Although there is a male side plastic tab that snaps into the jack and holds the two parts of the connector together, it is quite fragile…. Even a moderate pull down can pull the plug out of the socket. Therefore, the M-Series connector is a very good choice in situations where automation devices are subject to motion and occasional abuse.
However, there is one thing to note. While the standard M-Series connector is a suitable choice for industrial connectors, achieving a reliable connection and the specified level of intrusion protection depends on the technician properly tightening the connector threads. Some connector suppliers have even introduced push-on connectors that can automatically lock to address this potential point of failure. Perhaps the most mature of these products is the Molex Brad Series connector, which is a direct replacement for the standard M12 connector. This connector product eliminates the threaded sleeve and replaces it with a reliable push-to-lock mechanism. As a result, simply pressing the two parts of the connector together ensures a perfect locking and reliable connection, completely eliminating the risk of no or intermittent signals. These connectors are available in a variety of configurations, including push-in and pull-out connectors with an IP65 protection rating.
The Ultra-Lock connector is a push-in locking option with an O-ring for foolproof connections and IP69K intrusion protection performance. (Photo credit: MOLEX)
When used in Ethernet applications, the M-Series and Molex Brad connectors can also be powered using the Power over Ethernet (PoE) standard and are available in Type A, Type B and 4PPoE models to support changing bandwidths and power levels.
IEC Power Connectors for High Power Requirements
The International Electrotechnical Commission (IEC) has defined various standards for power connectors in residential, commercial and industrial applications. For example, the IEC 60320 standard covers non-locking connectors for voltages and currents up to 250V and 16A respectively. Such connectors include large non-reinforced C13/C14 connectors as well as the larger C19/C20 couplers commonly found on electronic equipment in industrial applications – including computer power supplies and server enclosures. These couplers are generally considered to be non-heavy duty connectors.
In contrast, IEC 60309 locking connectors have been ruggedized – and can be used for industrial cables carrying voltages and currents up to 1000V and 800A, respectively. All IEC 60309 locking connectors offer a degree of intrusion protection, with standard configurations proving IP44 splash-proof, IP67 waterproof or IP66/67 jet-proof, water-resistant protection.
The standard also allows for interlocking sockets: connectors are only allowed to be energized if they are mated to a plug… and the plug cannot be removed until the power is disconnected. The following color coding indicates the allowable voltage and frequency range of the connector.
Yellow indicates that IEC 60309 power connectors are suitable for transmitting voltages from 100 V to 130 V at 50 Hz or 60 Hz.
Blue indicates that the IEC 60309 power connector is suitable for carrying 200 V to 250 V at 50 Hz or 60 Hz.
Red indicates that the IEC 60309 power connector is suitable for carrying 380 V to 480 V at 50 Hz or 60 Hz. Typically 3-phase configuration.
Conclusion
Heavy-duty connectors must meet a variety of requirements. Does the connector need to resist being crushed – or pulled apart – by shock loads? Does it need to be protected against dust or water intrusion? What temperatures do the connectors need to withstand? Can heavy-duty connectors be installed in environments with flammability issues?
The number of pins and the voltage and current each pin will carry must also be considered – as well as the direction of cable entry and the level of cable protection. On automated machines, suitable connectors and cable clamps must be provided if the cables and their connectors need to be moved… And anti-kink devices are also prudent.
For relatively light electrical loads but operating in harsh environments, M-Series connectors and their derivatives are often the appropriate choice. For higher electrical loads, rectangular connectors may be a better solution…. In particular, these connectors can be configured with different cable entry orientations, mounting options and general modular building blocks to meet almost any complex requirement. And, for simple power connections for single-phase or three-phase AC supplies, IEC 60309 locking industrial connectors are the primary (if not the only) choice.
