Designing industrial motor control switchboards is usually the exclusive domain of electrical engineers, but solving the problem of containing the catastrophic arc-fault flash and arc-blast required PTAS to employ a multi-discipline engineering collaboration. We tested and had certified a new modular compact IP66 outdoor switchboard system design developed and manufactured by PTAS for our industrial and utilities customers.

High Public Exposure Risks

Switchboards in this category service 90% of outdoor public utility pump stations and heavy industry equipment. They are made from either aluminium or stainless steel, PTAS decision to test both construction materials demonstrated some expected differences in containment performance.

The new standard (AS/NZS 61439.1: 2016) requires that switchboard manufacturers physically test their products. It’s expensive, and as we found out not every test goes to plan. However, the team at PTAS was ultimately rewarded with success, the new design is proven and achieved NATA Certification (IEC/TR 61641:2014).

Arc-fault Explosions

While incidents that maim and kill are fortunately rare, the human effect of being caught in an arc-blast event can be catastrophic; unfortunately they occur with disturbing regularity.

Arc-Flash & Arc-Blast Characteristics

Arc-faults generate some impressive and unpredictable explosion characteristics; first is the supersonic pressure wave that blows the subsection door open, that’s followed out by the 22,000 deg C toxic gas flow with vaporised copper (a 67,000 x expansion), and associated shrapnel that destroys anything that gets caught in the way. There is also the blinding UV and IR light and deafening 165dB sound. With an energy density beyond 40 cal/cm2 maintenance operators are required to wear clumsy ‘bomb suits’ to do their job. (Search: arc-blast incidents)

Increasing Safety and Productivity

Our opportunity to rethink outdoor IP66 switchboard design also enabled PTAS to add design features that increases safety and productivity; for example, innovations in the door design makes it safe for maintenance and operating staff to safely work from the switchboard internal escutcheons, without shutdown or attendance of registered electricians. Systems can be safely kept online during maintenance.