Shape Memory Alloy Based Safety Latch

Votes: 19
Views: 5528

GM Offers an Improved Safety Technology for Electrical Boxes
Electrical safety is important in every location. Knowing the difference between an electrical device that is energized with electricity and one that is de-energized is important if you are going to perform work in an electrical panel box. Many electrical panel boxes are complicated and just because main the power disconnect lever is pulled, it does not mean that it is safe. Energy can still be present that can cause shocks, arc flashes, or even electrocution to those individuals servicing the panel. Possible sources may be incorrect wiring, external device add-ons, and the presence of residual charge from capacitors. GM has invented a device that indicates to the operator that an unsafe level of energy remains in the panel by the engagement of a safety latch mechanism utilizing (SMA) technology along with an audible or visual alarm.

Safety switches for power distribution panels, industrial control panels, Household HVAC, other service panels in energy applications.

Automatically stays locked if it detects residual energy and automatically unlocks when the energy is dissipated.
Single unit can be used with a wide range of AC or DC voltage applications.
No external power needed for operation.
Robust, inexpensive, compact package.

GM Patented Technology
The SMA Secondary Safety Latch and Lock mechanism will be engaged when the main power disconnect lever of the machine is moved to the disengage position. When engaged, any charge on the power lines would conduct current and resistively heat the SMA actuator. When heated, the actuator contracts engaging the locking pin, making it impossible to open the panel door this alerts the operator that energy still remains inside the box. The SMA actuator and the indicator (LED, Buzzer) could also act as current loads and drain any capacitive residual charge. When the charge is removed or depleted, the SMA actuator cools, and is reset by the biasing spring, unlatching the lock and indicating to the operator the panel is safe to access. The system could also include an optional bypass mechanism so the system can be serviced in special situations by trained individuals.

Contact: Mark Vann 586-563-9159 This email address is being protected from spambots. You need JavaScript enabled to view it.


  • Awards

  • 2016 Machinery/Automation/Robotics Category Winner
  • 2016 Top 100 Entries


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  • Name:
    Nicholas Pinto
  • Type of entry:
    Team members:
    Nicholas W. Pinto, Chandra S. Namuduri,  Suresh Gopalakrishnan, Nancy L. Johnson, and Mark Vann, General Motors, Warren, MI USA
  • Software used for this entry:
    Internally developed Shape memory alloy design tool
  • Patent status: