Understanding The Options For Motor Disconnect Switches—PART II

Understanding The Options For Motor Disconnect Switches—PART II

Open any catalog of motor disconnect switches, and you may be overwhelmed by all the different design options. Does your disconnect need to be fusible? What is the best type of enclosure for your application? Is it a 1Ø or 3Ø switch requirement? What HP is needed? Do you need an installed pilot device?

The list could go on and on, and for good reason nowadays. Far from being simple ON-OFF devices to meet LO/TO requirements, motor disconnects increasingly have to meet challenging electrical or installation requirements, and in many cases, you may need a specialized switch to meet those requirements.

In this segment on our motor disconnect series, we'll examine some key options and customizations you may require when specifying a motor disconnect.

Electrical Options As you configure your disconnect, it's important to keep the following electrical options in mind:

  • Fusible or non-fusible. Your application will likely determine if the switch should be a fusible or non-fusible type. Fusible switches have a fuse provision in the switch and enclosure assembly, enabling you to open and close the circuit while providing overcurrent protection. Non-fusible switches do not have an integral fuse option and provide no circuit protection. Quite simply, does your need require fuse protection at the switch, or is there upstream protection to eliminate this need at the switch? MENNEKES offers both non-fusible UL508 or fusible UL98 disconnects.
  • Pole and throw options. Is the voltage requirement 1Ø or 3Ø? This will determine the number of poles to match the voltage configuration and related HP rating. Most industrial requirements use 3 pole switches, but MENNEKES also stocks 6 pole disconnects in both non-metallic and stainless enclosures. These are a perfect disconnect means for two-speed or reversing motors. Off-the-shelf availability and compact size make them especially useful for motor control applications. As an added option, we offer 6 pole double throw disconnects with a center OFF position to transfer loads from one power source to another.
  • Pilot device. Do you need a pilot device as well as a disconnect in the same enclosure? Normally a separate enclosure is required to mount these devices. With MENNEKES disconnects, you can customize your disconnect and add a pushbutton, selector switch or pilot light in the same enclosure. We stock many 22.5mm and 30mm pilot devices, or we can assemble to your specifications.

Enclosure Options When it comes to housing your electrical devices, the more installation and design options you have, the better. Some of the key enclosure options include:

  • Extra space. A little extra space in the box can make it faster and easier to install. MENNEKES stocks many disconnects in an extra-large enclosure. This also allows for factory installed or on-site customizations.
  • Material options. Disconnect enclosures come in both metallic and non-metallic versions. Both have their advantages. Metallic boxes maximize the impact resistance for high-traffic and end-of-line applications in packaging, manufacturing and pharmaceutical facilities, while non-metallic enclosures generally have a lower installed cost and increase customization options. Our non-metallic AMAXX products, for example, let you freely combine multiple disconnects and related devices in a single enclosure, saving time, installation cost and space.
  • Environmental resistance. The type of enclosure will also determine which operating environments the disconnect can tolerate. Most food processing or wash down applications require Type 4X watertight enclosures to withstand cleaning agents. Our sloped-top stainless enclosures provide this protection and shed liquids and contaminants.

To learn more, refer to Article 430 of the National Electrical Code for additional information about how to properly size a disconnect switch for single motor and combination load applications. For more information on MENNEKES motor disconnect options, download our product catalog.