Automation Canada Quarterly Volume 2 Issue 5 - 11

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 nonfusible 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 makes 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
22.5 mm and 30 mm pilot devices, or we can assemble to your specifications.

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
washdown applications require Type 4X watertight enclosures capable of
withstanding cleaning agents. Our sloped-top stainless enclosures provide
this protection and shed liquids and contaminants.

MOTOR DISCONNECTS FOR VFD APPLICATIONS
In the right applications, variable frequency drives (VFD) will improve the
control and reduce the energy costs of your AC motor-driven equipment. To
install a VFD safely, however, you may need to reconsider the type of motor
disconnect you use. The traditional knife-blade style of disconnect, while
compliant with the National Electrical Code (NEC), is not the best choice for
modern VFD applications. The reasons why are both physical and electrical.
From a physical standpoint, the traditional NEMA-style blade disconnects
are too bulky for IEC installations, which often group or combine motor
controls and disconnects in a shared enclosure or in limited spaces. In these
applications, the best alternative is a compact rotary disconnect. The use of
rotary disconnects, in nonmetallic or stainless steel enclosures, continues to
grow in popularity as more and more machine builders and OEMs adopt IEC
devices.
From an electrical standpoint, VFDs require motor disconnects with an
auxiliary contact that can provide crucial early break functionality. This contact
signals the drive before disconnecting the motor, giving the drive time to
power down in a controlled manner before the mains open. Plenty of
disconnects, both blade- and rotarystyle, offer an auxiliary contact. But
disconnects are not all created equal when it comes to protecting expensive
VFDs.
ENCLOSURE OPTIONS SAVE TIME, SPACE AND COST
For one thing, auxiliary contacts have speed differences based on their
When it comes to housing your electrical devices, the more installation and actuation methods. Cam actuated versions provide fast and predictable early
design options you have, the better. Some of the key enclosure options break switching. Our onboard cam-actuated auxiliary contacts will provide a
include:
minimum, repeatable time gap of 20 ms between the opening of the auxiliary
* Extra space. A little extra space in the box can make it faster and easier to and the opening of the mains. This repeatability and speed provide an
install. MENNEKES stocks many disconnects in an extra-large enclosure. This advantage over conventional auxiliary contacts with mechanical linkages
also allows for factory installed or on-site customizations.
whose actuation speeds can vary based on how slow or fast the switch handle
* Material options. Disconnect enclosures come in both metallic and is operated.
non-metallic versions. Both have their advantages. Metallic boxes maximize
For another thing, auxiliary contacts aren't always included in the price of
the impact resistance for high-traffic and endof-line applications in packaging, the base disconnect. In our case, auxiliary contacts are included as a standard
manufacturing and pharmaceutical facilities, while non-metallic enclosures feature. Both auxiliary contacts and early break capability can be options with
generally have a lower installed cost and increased customization options. Our other manufacturers at an added cost.

C A N A D I A N A U TO M AT I O N

VOLUME 2, ISSUE 5

https://www.mennekes.com/pdf/white-papers/MENNEKES_WP_MotorDisconnects.pdf https://www.mennekes.com/ https://www.mennekes.com/ https://www.mennekes.com/

Automation Canada Quarterly Volume 2 Issue 5

Table of Contents for the Digital Edition of Automation Canada Quarterly Volume 2 Issue 5