Having Custom Switchgear and MCCs Can Reduce Overall Project Cost

Types of Switchgear | Low Voltage Switchgear | Medium Voltage Switchgear | What is an SCCR Rating? | What Is an MCC?

If you need help deciding on the optimal switchgear or if you need a custom motor control center (MCC) for a new application or upgrade, we have solutions that will meet your needs and reduce your overall project cost. We can also help you decide which types of switchgear would be best for your application. Get in touch with our team of experts today to learn more.

Types of Switchgear

Low Voltage Switchgear

Medium Voltage Switchgear

What Is an SCCR Rating?

What Is an MCC?

What Types of Switchgear Do I Need?

Electrical switchgear is often found in industrial and manufacturing plants as well as electric transmission systems. It is used to not only provide power to all equipment in an industrial facility but also protect electrical devices and control and isolate circuits when there are potentially dangerous systems issues. It does this by reducing the current flow through the system where needed. Switchgear is comprised of switches, circuit breakers, and fuses mounted together in a metal enclosure. Switchgear is classified by the maximum voltage it can service and is generally specified by low voltage, medium voltage, high voltage, and extra-high voltage.

What Should I Consider for My Low Voltage Switchgear?

Low voltage switchgear is rated for voltages up to 600V. This metal-enclosed switchgear contains three main compartments, one for breakers, another for buses, and another for cables. It is a three-phase power distribution device that is commonly located on the low-voltage side of a power distribution transformer. The switchgear and transformer are often used to supply low-voltage motor control centers and switchboards. Some things to consider when selecting switchgear include:

  • Voltage ratings
  • Amperage requirements
  • Power circuit distribution
  • Status feedback and communications requirements
  • Load types and applications
  • Interrupting device requirements
  • Insulation mediums
  • Access options
  • Arc resistance
  • Switchgear type
  • SCCR rating

What Should I Consider for My Medium Voltage Switchgear?

Medium voltage switchgear is rated for voltages between 600V and 69,000V. Enclosures for the switchgear are available for indoor and outdoor use. Medium voltage switchgear is typically required to have front and back access for proper installation and maintenance. Medium voltage switchgear designed for front access can be mounted against a wall to save space. Insulating mediums are required with medium voltage switchgear and can be air, light oil, or gas. As previously mentioned in the low voltage switchgear section, some things to consider when selecting switchgear include:

 

  • Voltage ratings
  • Amperage requirements
  • Power circuit distribution
  • Status feedback and communications requirements
  • Load types and applications
  • Interrupting device requirements
  • Insulation mediums
  • Access options
  • Arc resistance
  • Switchgear type
  • SCCR rating

There are various types of medium voltage switchgear, including: 

  • Metal-Enclosed
  • Metal-Clad
  • Pad-Mounted
  • Gas-Insulated
  • Vault or Subsurface
  • Arc Resistant

What Is an SCCR rating?

Short-Circuit Current Rating (SCCR) refers to the maximum short-circuit current over a specified time that the switchgear assembly can safely withstand without sustaining shock or fire hazard. This timeframe is usually a minimum of four cycles for 60Hz. The SCCR rating is typically driven by the overcurrent protective device, the circuit breaker, or fuse. The rating ensures that the switchgear is properly sized for the system. The switchgear's SCCR rating must be able to handle the SCCR of the lowest-rated breaker used in the switchgear.

What Is an MCC?

A motor control center or MCC is a series of metal cabinets from which multiple motors can be controlled and monitored. MCCs are commonly found in mechanical or electrical rooms. They contain various sections with a common power bus. Each section contains a combination starter, consisting of a motor starter, circuit breaker or fuses, and a power disconnect. These sections are often referred to as "buckets." Each bucket can operate independently or coordinated using interlocks or a PLC.

MCCs will contain motor control devices such as reduced voltage soft starters (RVSS), across-the-line starters, and variable frequency drives (VFDs). They can also contain other control devices such as programmable logic controls (PLCs), push buttons, indicator lights, and metering equipment.

At AIC, our subject matter experts can work with you to design and replace your MCC buckets or supply custom MCC buckets that meet your operational needs. Get in touch with us today to get the process started.

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