Article
Motor disconnect switches are a critical safety element in industrial settings, but just how much protection they provide – and how long they last – is dependent on how well each switch is matched to its setting. Specifiers have a number of options to choose from, including housing materials and internal electronics.

Making the Connection: Matching Disconnect Switches to Their Application

Chuck Ross
Motor disconnect switches are a critical safety element in industrial settings, but just how much protection they provide – and how long they last – is dependent on how well each switch is matched to its setting. Specifiers have a number of options to choose from, including housing materials and internal electronics.

According to Paul DiAntonio, industrial product manager with MENNEKES Electrical Products, the selection process should begin with an understanding of the environment in which a switch will be operating. Cleaning requirements, impact exposure and other plant conditions need to be considered when evaluating stainless steel and polymer disconnect switch options.

“Stainless steel has better impact resistance, which can minimize incidence of damage and required maintenance, and corrosive cleaning agents can affect enclosure integrity,” which can be another argument in stainless steel’s favor, DiAntonio says, though resin-based products also can perform well. “Nonmetallic alternatives should also be considered, as specific polymer resins provide similar, or even better, resistance to food-plant cleaning solutions and wastewater atmospheric conditions.”

However, specifiers should know that not all nonmetallic products are alike. For example, DiAntonio says, manufacturers use varying materials and gasketing methods for their products, so specifiers need to investigate the suitability of products to their specific project demands.

Of course, specification needs to cover more than just the housing material – switches also need to be matched to an installation’s particular electrical requirements, including whether or not a switch needs to be fusible. And the reason why an installed switch might need replacing also can influence the selection process, according to DiAntonio. For example, redesigns involving branch motor circuits often require disconnects with auxiliary contacts. And if efficiency upgrades include switching to variable frequency drives, “disconnects with early break auxiliary contacts should be considered.”
Photo courtesy of MENNEKES Electrical Products
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