Connectors moving up the curve

Historically, connectors designed specifically for distributing power have been comparatively slow to adapt to changing needs. This product segment had not attracted major investment in research and design for a variety of reasons, including relatively low sales volume, highly customised application requirements and possible liability issues.

Electronic product designers are particularly sensitive to the potential for shock and burns, as well as catastrophic system failure due to faulty connectors in high power environments.

The basics of power connector design have been established over many years, and Ohm’s law still applies. Niche connector suppliers dominated the available market, offering products that often tried to be all things to all people.

But within the past 10 years, things have rapidly changed. The industry has been reinvigorated as demand for higher current, greater packaging density, compatibility with thermal management strategies and greater design flexibility became prime design criteria.

Large connector manufacturers, including Amphenol, FCI Electronics, Molex and Tyco Electronics, have greatly expanded their existing power connector ranges using innovative modular tooling that allows the production of economical, near custom combinations of signal and power contacts.

Suppliers who have carved out a niche specifically in the power connector segment have felt the competitive pressure and responded with a greater variety of products using both traditional screw-machined and more economical stamped-and-formed contacts.

Contact and bulk resistance at the interface have been reduced through the use of new contact designs that ensure redundant points of contact, as well as adopting new contact materials featuring higher conductivity while maintaining essential spring characteristics.

The traditional 30°C maximum contact temperature rise is still the gold standard for contact ratings, but suppliers may provide data on performance well past this temperature limit.

As all classes of electronic products continue to shrink in size, current density becomes a key measure of connector efficiency.

Board-mounted connectors are now commonly rated by amps per linear cm. Suppliers are tweaking the balance between connector height and width to achieve the highest current rating without consuming too much vertical space.

As the packaging density of electronic products continues to increase, the ability to transfer heat out of the box becomes more of a challenge. Power connectors are not only a source of heat, but their typically large housings can obstruct cooling airflow.

Newer connectors feature lower profiles and, in some cases, offer vented housings that can result in higher current ratings of the contact.

These changes have been good news for system designers who now have many more options among multiple suppliers and are able to more closely match a catalogue interface with their specific application requirements.

Several suppliers have set up micro-websites designed to assist in the selection of the most appropriate power connector for a given application.

Although more accurate and better-documented performance data is now readily available, engineers still tend to routinely derate power connectors by up to 50%.

They will request data sheets and order samples to verify performance in their particular application. Derating connector performance data that may have already been derated by the manufacturer results in larger, more costly power connectors, but the lingering fear of smoking equipment often results in very conservative power connector selections.

New power connectors continue to enter the market to address emerging needs. Connectors designed for rugged environments often require protection from liquids and dust. IP65 and IP67 define the ability of a connector to provide sealing from these contaminants.

Hypertac, for instance, has introduced a new two- and three-position connector with up to 300 A contacts. The HBB family of connectors is focused on high-reliability/high-current applications that demand increased power density. These connectors are rated up to 1000 V using a 9 mm diameter pin.

The King Cobra circular connectors from Positronic Industries feature 20 A contacts and are environmentally rated to IP65.

A particularly active portion of the power connector market has been focused on the needs of power supply manufacturers. Requirements for redundant fault tolerant systems have generated a huge market for modular blind mate power supplies in server and data centre equipment.

Increasing current density per linear cm of PCB edge has created a battle for connectors that can support larger loads while consuming minimal space.

Connectors such as the EXTreme Ten60Power from Molex, the HCI connector system from FCI Electronics and the Multi-Beam XLE from Tyco represent a progression of power connectors that address this.

Another trend that has pervaded this industry is movement away from proprietary interfaces. In the past, manufacturers produced unique styles of power connectors, which often forced consumers into sole sourced situations. Large OEMs began to insist on at least one viable second source capable of providing electrically and mechanically identical product.

As a result, many suppliers have begun cross-licensing select portions of their product mix. Tyco can provide the HCI connector from FCI Electronics, while FCI has become a source for the Tyco MultiBeam XLE. FCI has also teamed up with Harting and is a certified second source for the Outdoor PushPull I/O Connector, which is a high-density IP67-rated hybrid connector that is designed for equipment exposed to extreme weather conditions.

One solution to reducing the size of power distribution systems, including the connectors, is to increase the voltage, with a corresponding decrease in current.

Most data centre, storage and server farms today distribute 12 VDC or 48 VDC to the shelf. There has been talk within the industry about the advantages and challenges of increasing the voltage to the 350-400 VDC range, which could offer significant improvement in efficiency of the distribution system.

Cable conductors and bus bars could be dramatically shrunk, but would also have a significant impact on many existing power connector designs, in terms of creep and clearance dimensions, as well as human safety issues. We are seeing several new connectors being introduced with a ‘touch-safe’ feature.

The PowerMod HP connector family from Anderson Power Products is rated up to 450 A. Both male and female connectors are touch-safe in the unmated condition.

The expansion of the market for portable medical diagnostic and treatment equipment may represent a growth potential for low to medium power connectors.

Global interest in developing alternative sources of electrical energy has opened opportunities for new application-specific interfaces in both the solar- and wind power-generation industries.

These connectors must be designed to provide high reliability in extreme environments, including wind-driven moisture, intense UV radiation and salt spray that may exist at the top of a wind turbine, on the face of large solar cell arrays or in underground power distribution vaults.

The introduction of more hybrid and all-electric vehicles will touch off a scramble for a standardised charging connector. It is unclear how the industry will settle on a common interface for use in both commercial charging stations and in the garage of the consumer.

Connectors from Yazaki and ITT Interconnect Solutions have already entered the market.

The ‘green’ movement is impacting all consumers of electrical energy, including large data centres, which often measure usage in megawatts. Growing interest in achieving Energy Star certification of data centres is another factor that is stimulating consideration of every element of the power distribution system.

Since the efficiency of the connector determines how much energy is ‘consumed’ by the interface, improving conductivity at the interface may become a selection factor. Not only is energy lost in the connector, but also the resulting heat may require mechanical refrigeration, adding to the total energy consumed.

Positronic Industries has begun to explore this aspect of connector performance by publishing a series of charts that defines the estimated annual energy attributed to loss by a power connector under a variety of contact loading options. It is unclear if this will become a factor in the power connector selection process, but it does provide insight on the performance of the connector relative to others.

Even more specialised connectors are being developed to address the needs of specific industries. Equipment designed to operate in potentially explosive environments may require the ability to connect and disconnect power under load.

The Star-Line EX Series from Amphenol Industrial offers configurations for power up to 1135 A at 1000 V. Inserts allow combinations of power signal, coax and fibre contacts. These explosion-proof connectors find applications in mining and oil refineries.

Additional power connectors with highly unique characteristics have been developed to address applications in nuclear power generation, space and undersea exploration.

These niche connector segments have proved to be fertile ground for a group of very small specialty manufacturers such as Vantage Technology, which provides unique connectors featuring spring-loaded inserts designed for hazardous environments.

The market for power connectors has moved out of the backwaters of connector design and will likely continue to attract greater resources for innovation as demand for greater efficiency and power density become top priorities.

Bishop & Associates comments:

1. Many new connectors designed for power delivery applications have entered the market over the past 10 years, and more are in the pipeline.
2. Newer connector families feature modular design, higher current ratings and can facilitate system cooling strategies.
3. Increased competition in this segment has resulted in somewhat lower prices per watt delivered.
4. Power connector suppliers have begun establishing cross-licensing agreements to ensure reliable and competitive supply of this critical component.
5. Printed circuit board-mounted power connectors are now being measured in terms of watts per linear cm, and are being adjusted to optimise the height-to-width ratio.
6. The lack of standardised current rating test methods continues to encourage system designers to derate connector manufacturers’ published current ratings.
7. Opportunities for new specialised power connectors exist in automotive, alternative energy generation and ruggedised/environmentally sealed applications.

Robin Pearce, Bishop & Associates

rpearce@bishopinc.com