Intelligent motor control centers help drive energy, productivity savings

Manufacturers are continuously seeking new ways to increase productivity, streamline processes and boost their profit margins. Plant engineers can play an important role in this effort by helping to select and implement control solutions that reduce costs, save time and increase the flow of information within automation systems.

08/01/2009


Manufacturers are continuously seeking new ways to increase productivity, streamline processes and boost their profit margins. Plant engineers can play an important role in this effort by helping to select and implement control solutions that reduce costs, save time and increase the flow of information within automation systems. But with myriad choices available, it’s easy for engineers to overlook one of the keys to success: leveraging technological advances to integrate smart devices, device-level networks and software into motor control systems.

Traditionally, motor control centers (MCCs) contained only electromechanical components with hardwired connections. While these components remain the workhorses of MCCs, advances in solid-state technology have resulted in more intelligent, programmable devices that do more than just turn on and off a motor. Today’s MCCs monitor motor current and thermal capacity, perform protective troubleshooting functions and provide detailed diagnostics to help avert downtime.

These intelligent MCC designs also address some of the configuration and data-management inefficiencies that device-level networks can create, which include:

  • Reliability and flexibility shortcomings associated with typical daisy-chain architectures such as adding new units or accidental breaks in the chain that can affect downstream units in that connection, potentially shutting down equipment

  • Potential damage to exposed trunk-line and drop-line network cables in the wireways when pulling and installing other power cables

  • Integrating motor control data into the plant control system, and sorting through the enormous data available on the network to find needed information.

    • Complete integration

      The intelligent MCC integrates three major system components %%MDASSML%% communications, hardware and software %%MDASSML%% to address these issues. While early versions of MCCs with communication networks contained variations of these elements, today’s solutions leverage a harmonized design that deliberately integrates these elements into a unified solution.

      A standard MCC installation requires extensive interwiring, documenting and testing in the field. Pretested and pre-configured, the intelligent MCC arrives ready to install. Communication cables are installed and tested at the MCC factory, while software screens come pre-configured for the specific MCC. Additionally, intelligent devices are preprogrammed with baud rate, node number, trip current and other settings.

      Communication network capability lies at the heart of an intelligent MCC. The network replaces the traditional control interwiring with a single communication wire. Ideally, all the units have input points to monitor devices such as the disconnect switch, contactor, overload relay or pilot devices. In addition, a network scanner module or network linking device connects the MCC to the plant control network, and collects and distributes the device data in the MCC.

      The type of MCC you select for your application can have a significant impact on overall cost, installation time and monitoring capabilities. Therefore, it’s important that engineers carefully evaluate the core components of an intelligent MCC system.

      Proven, open communication network %%MDASSML%% The trend toward open networks (as opposed to proprietary networks) has clear and well-documented advantages. The network should provide proven performance, offer a low cost per node and be accepted by a wide range of suppliers and users.

      Optimized physical construction %%MDASSML%% The traditional approach for routing network cables in MCCs is through horizontal and vertical wireways. Although this method works, consider these more optimized approaches: