Industrial Connectors for Power, Protection, and Reliability

By David Smith | December 03, 2024

Safe and reliable power distribution is critical in industrial, energy storage, renewable energy, transportation and agricultural equipment. Selecting among the many good connector choices can be challenging.

Designers of power distribution systems must look beyond the foundational specifications of voltage, current, operating temperature, and basic shock and vibration needs when selecting industrial connectors to also consider factors like ingress protection (IP) ratings, locking mechanisms, chemical and corrosion resistance, and hot pluggability.

IP ratings for industrial connectors are designed to ensure reliable operation under specific environmental conditions. They consist of two numbers. The first indicates the level of protection from solid objects and dust getting into the connector and the second indicates the amount of protection from liquids getting inside. A “0” in either position indicates no protection.

The highest rating in the standard IP scale is IP69. IP69-rated devices are dust-tight and can withstand high-pressure liquids and steam cleaning. One level down is IP68 that’s given to devices that are dust-tight and can withstand being submerged in water up to 1.5 meters deep for up to 30 minutes.

Examples of connectors with IP68 ratings include the Samtec ACR-16 and the SBSX-75A sealed waterproof connectors from Anderson Power Products. The ACR-16 is a 10-position connector with a current rating of 11.6 A and the SBSX-75A has two power pins rated for up to 135 A plus up to four signal pins. Both connectors also include locking mechanisms, but different styles of locking mechanisms (Figure 1).

Figure 1: SBSX-75A connectors feature IP68 environmental ratings and locking mechanisms (not to scale). (Images: Sager)

Locking mechanisms

Locking, or latching, connectors are designed to prevent accidental disconnects and provide a secure and reliable connection. They are widely used in automotive, energy storage, industrial, medical, and other applications. For example:

The ACR-16 series are bayonet style connectors that lock as they’re mated and twisted. They can be mated or unmated with a 1/3 turn.
The SBSX-75A series uses a latch lock and has stainless steel spring latches on the sides that snap securely into place.

A variety of other latching/locking mechanisms is available including:

Lever locking is a very common mechanism on industrial connectors. It prevents the connector from opening and increases the tightness of the connection. The Hirose push-pull locking uses inner latches in the plug that retract as the two halves are pressed together and they slot into matching grooves inside the receptacle. Disconnection requires that the connector body be squeezed while the connector halves are pulled apart.

Screw locking uses threaded couplings to improve shock and vibration performance. Screw locking is used on rectangular connectors as well as circular connectors.

Chemical and corrosion resistance

Even for locked and sealed connectors, exposure to hydrocarbons and solvents found in transportation, industrial, and mobility applications can degrade standard housing materials. For those applications, connector housings are available with chemical and corrosion resistance materials.

Polycarbonate (PC) exhibits good chemical resistance to dilute acids, neutral salt solutions, greases, oils, and detergents.
Polybutylene Terephthalate (PBT) is suitable for applications where exposure to organic solvents, gasoline, and oils is expected.
PC/PBT blends combine the best properties of both polymers and have high chemical resistance, high impact performance, and excellent weatherability.

Chemical resistant housings using a PC/PBT blend are available in the SB connector series from Anderson Power Products. These connectors are rated up to 280 A, have an extended operating temperature range of -40 °C to 105 °C, and an IP64 environmental rating (Figure 2).

Figure 2: The housing of this power connector is made from a PC/PBT blend that provides high chemical resistance. (Image: Anderson Power Products)

Hot plugging

Modular systems can deliver increased reliability by using hot-pluggable connectors. In other cases, service plug connectors, also called cold plug connectors, are needed to disconnect the electric circuit and ensure the safety of workers in high-voltage areas.

Hot plugging supports live connector insertion and extraction for maximum system availability. There are two hot plug configurations:

Premating, or make-first/break-last, sequences the contacts so they engage prior to the main power contacts. Premating is used as a protection against excess currents, short circuits and ground faults.
Postmating, or make-last/break-first, sequences contacts used for signal or auxiliary power positions to ensure communications are not started or power circuits switched on until the power contacts are fully engaged.

Powerpole connectors from Anderson Power Products are rated for 600 V, up to 350 A and feature premating. The flat wiping contact system has a large normal force and large conducting area to minimize contact resistance. The sacrificial tip confines damage to non-conducting surfaces when mating or breaking under load. When mating, whether under load or not, the wiping design cleans the mating surfaces.

Cold plugging

High-voltage applications (1,500 V+) often focus more on operator safety than system uptime. In those cases, a service plug can be used for cold plugging to manually disconnect the power and protect operators from high voltages.

The Hirose EM30MSD service plug includes power terminals rated for 1,500 V and 200 A and signal lines rated for 250 V and 1 A that are interrupted to prevent hot swapping when the bayonet locking mechanism is rotated for disconnection. When engaged, the locking system also provides shock resistance to minimize the possibility of accidental disconnects (Figure 3).

Figure 3: When the EM30MSD cold plug connector is unmated, both the power and signal lines are opened to protect operators. (Image: Hirose)

The multipoint contact design reduces contact resistance. The PBT housing of the EM30MSD service plug provides chemical resistance, and when mated, has an IP68 rating for environmental protection.

When unmated, the receptacle section features IPX2 finger protection to reduce the risk of shocks to operators. The IPX2 design protects against the entry of solid objects larger than 12.5 mm in diameter and longer than 80 mm, like a finger.

Custom cable configurator

Selecting connectors is an important task. So is using those connectors to design a cable assembly. Molex’s Custom Cable Configurator streamlines this process.

Designers can use this online tool to quickly design custom cable assemblies. After the design is completed, the tool delivers a concept drawing, 3D models, samples, and a quote from Sager Electronics. Features and capabilities include:

Choice of power and signal connectors
UL-rated wire options
Support for dual- and single-ended designs
Options for bundling accessories and customized labels

Advanced features include a pin-out configurator and automatically generated drawings and 3D models.

Selecting industrial connectors and designing cable assemblies that deliver power, protection, and reliability is a detailed process. It involves considerations of connector IP ratings, latching/locking mechanisms, plus chemical and corrosion resistance.

Visit Sager Electronics for solutions that simplify the design process and provide an optimal solution for your applications.