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Should You Use a Motor Control Center or an Arc Armor Enclosure

Romtec Utilities designs, manufactures, and supplies complete pumping systems for all types of applications with all structural, mechanical, electrical, and communications components included. Control panels are an integral piece to any pumping system, and there are many different configurations that can provide robust pump station controls. Two common and reliable configurations are the motor control center (or MCC) and Arc Armor enclosures. These two control options provide very similar benefits for pump station operators, but each option is distinct, offering specific advantages and drawbacks in different scenarios.

Robust MCC Panel Offering Controls and Protection From High Voltage

To understand an MCC or an Arc Armor enclosure, we will define the elements that make up each section of the panel. The first section is the main power connection. This is where utility power is wired into the panel. The next section is the motor control section. Electrical power is connected directly to separate motor controls in this section. The third section is the actual control device or remote terminal unit called the RTU. The RTU is a logic device that can function as a PLC or with relay logic. An MCC can include additional compartments for more functionality such as an automatic transfer switch for generator power or a low power compartment for lighting and other features. Arc Armor enclosures also offer a fourth section that is typically used for gas isolation and venting from wastewater lift stations.

An MCC and an Arc Armor enclosure both compartmentalize elements of the control panel. By separating these elements, each section uses a different electrical load. This provides operators and maintenance personnel safer access to each section of the panel by reducing exposure to high currents of electrical energy. For compartments with more electrical energy, personnel will follow regulations for accessing these areas, wearing the appropriate personal protective equipment or PPE. According to the OSHA website, there are 5-10 arc flash incidents every day in the United States. MCCs and Arc Armor enclosures reduce the potential for these incidents and drastically reduce the probability of a serious injury or fatality from an arc flash. Safety is a great advantage of both configurations, but each configuration has its own strengths for being used on a pump or lift station project.

A Very Safe and Relaible Control Panel

Arc Armor enclosures offer faster lead times compared to MCC panels, which can be advantageous for any pumping system project. Arc Armor enclosures are readily available and can be configured with UL listed controllers from a variety of manufacturers. An Arc Armor panel can include a logic relay, a PLC, VFDs, separate motor controls, and many other components. Arc Armor panels can also include generator receptacles to connect with an automatic transfer switch and to a backup generator. For pumping applications with these typical types of needs, an Arc Armor enclosure for the control panel is faster and more affordable then an MCC style of panel.

Although an MCC has a longer lead time (around 2 to 3 times the production time of a different configuration), MCCs are much better suited for high load requirements on pumping systems with high horse power motors. Once pump motors reach 75 hp, an MCC begins to make more sense. MCCs are manufactured with bussing that connects each compartment, including power busses and ground busses if required. The bus wiring is more suitable to be manufactured for high currents of 3-phase electricity, as either 3-wire 3-phase or 4-wire 3-phase. This type of power supply is required for high horse power motors, and MCCs handle this type of power better than other panel configurations.

Large Control Panel with NEMA 3R Painted Enclosure

When it comes to designing and manufacturing electrical control panels for pumping systems, safety is a major consideration for Romtec Utilities. MCC panels and panels with Arc Armor enclosures are two great options for providing reliable and safely-accessible pump station controls. These two configurations each offer specific strengths that will make one or the other more suited to a specific project. Romtec Utilities designs robust pump station control panels with MCCs and Arc Armor enclosures all the time, and our electrical engineers will get you the best and safest controller for your unique pump station application.

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