In 2011, a grocery retail chain approached SafeConnect Systems, South Portland, Maine, seeking a safe electrical solution to power its new hybrid electric transport refrigeration units (eTRUs) to use with its fleet of refrigerated semi-trailers.

Initially, the grocery retailer wired its facility with traditional 4-pin high-voltage connection equipment to run the eTRUs on electric standby power. However, during a final review of the project, the company’s environmental, health and safety (EHS) staff recognized potential safety vulnerabilities with the design of the legacy equipment selected to connect the reefers (refrigerated trucks) to the electric grid. The company needed a system that would eliminate the potential for human error in making volumes of high-voltage connections and disconnections by many different operators with varying skill levels. The grocery retailer needed a safer system.

“At the time the customer reached out to us, there was nothing available on the market to meet their requirements. We contacted various manufacturers of hybrid eTRUs, and they were unable to offer any other type of electric standby connector aside from the traditional 4-conductor twist-lock designs. This need ignited a product development effort to find something different, something better, something safer,” says Bob Provencher, director of technology and sales at SafeConnect Systems.

After about two years of research and development, SafeConnect Systems launched the SafeConnect Electric Standby Connection System, designed specifically for use with eTRUs on both refrigerated trucks and trailers.

Electrical safety is key

What makes SafeConnect a true leader in the electric standby market is the company’s commitment to safety. While other electric standby systems use standard pin and sleeve or bladed twist-lock devices (4-pins), SafeConnect uses a proprietary 6-pin connection system, incorporating auxiliary contacts and a tension release feature, provided by the MELTRIC Corp., Franklin, Wis.

SafeConnect Systems chose MELTRIC as the manufacturer of SafeConnect electrical components because of MELTRIC’s proven dedication to innovation, quality and safety.

“We researched a lot of options for plugs and receptacles for SafeConnect, and MELTRIC was our No. 1 choice,” says Provencher. “Their products are inherently safe, providing features and protections not found in competing designs. Most importantly, they allow SafeConnect’s control circuit innovation to shut down all electrical power before the plug is completely removed from the receptacle. This was one of the biggest challenges we faced when designing the SafeConnect system. MELTRIC provides code compliance with the National Electrical Code (NEC) for motor disconnects. MELTRIC provided solutions for us that no one else could.”

Some key points are:

  • MELTRIC’s plugs and receptacles can withstand harsh outdoor conditions, including extreme temperatures.
  • Silver-nickel contacts, stainless-steel components and chemical-resistant housings help withstand corrosion.
  • Butt-style pressure contacts ensure excellent electrical connections, even in dusty or dirty environments.
  • Type 4X/IP69K environmental rating/ingress protection helps ensure watertight connections.
  • MELTRIC plugs and receptacles are UL/CSA-rated for motor circuit and branch circuit disconnect switching.
  • They are NFPA 70E “line of sight”-compliant and are ideal for fast, easy, plug and play connections.

The SafeConnect system can only be energized by first joining the plug and receptacle together and then pushing the “ON” button. Connecting the docking station’s 6-pin, spring-loaded receptacle to the 6-pin truck/trailer-side plug closes the control circuit, and only then is high-voltage power allowed to flow through the system.

In the event of an operator error, such as a driver neglecting to press the “OFF” button before disconnecting, no harm will occur to the operator, the plug or the receptacle. Any disconnection, even while under load, will completely de-energize the entire system before a dangerous electrical arc can develop.

The configuration of the 6-pin SafeConnect System, which uses varying pin heights to make and break electrical connections, mitigates the inherent risk of exposure to high voltage electricity. This reduces the risk of accidental electrical shock. Unlike previous legacy equipment, SafeConnect’s unattended cable and receptacle cannot be in an energized state without being connected.

Arc-proof technology

Electrical arcs can occur with legacy equipment when an electrical connection or disconnection is made without complete system de-energization. These arcs are extremely dangerous and can result in serious injuries, including electric shock and burns. Additionally, arcs can scar plugs and receptacles, which creates added electrical resistance that in turn leads to a voltage drop in the power distributed to the refrigeration unit. An eTRU motor then compensates for the voltage drop by drawing more amperage, which can result in equipment damage or malfunction.

Accidental drive-offs

Accidental drive-offs are a big safety issue with 4-pin twist-lock connectors. Should a driver forget to unplug, serious damage can result to the trailer and docking station, as the power cord gets ripped off by the vehicle pulling away. Worse yet, drive-offs can result in human exposure to live, dangerous, high voltage wires lying on the ground.

SafeConnect eliminates this scenario by using a spring-loaded, tension-activated plug/cable release. As soon as the system senses movement in the connecting cable, the receptacle and power cable automatically eject from the trailer’s plug. When this occurs, power instantly shuts down at the plug and receptacle, cable and control box, leaving no opportunity for exposure to live components.

EPA-SmartWay verified technology

Adding a SafeConnect Electric Standby Connection System to an eTRU operation makes sense on several levels. From an environmental overlook, SafeConnect facilitates compliance with stringent environmental diesel emission-reducing standards, including those of CARB.

Additionally, SafeConnect is an EPA SmartWay-verified idling reduction technology (IRT), which identifies SafeConnect as an innovative product that significantly improves the environmental impact of the trucking industry.

“By facilitating e-standby for eTRUs, SafeConnect is doing its part to help create a safer, eco-friendly future by protecting its customers’ people, equipment and bottom lines,” says Provencher.