10257 Plant Ventilation System
Summary & Goals
Customer’s plant was located in the South and had several roof top ventilation fans powered by buckets in MCC’s throughout the plant. Personnel had access to the controls of the buckets and were able to disrupt the balance of air flow in the plant creating hot spots and negative air pressure areas. Logicon was asked to integrate new MCC’s with DeviceNet and a central control screen in the maintenance shop to manage the control of the air flow in the plant.
Detail
Ventilation fans were over packaging areas of the plant where no air conditioning was present. Each area also included some process or packaging ovens increasing the heat rise in the areas. The customer ordered new Allen-Bradley MCC units that included DeviceNet starters and E1 Plus modules. A single DNET card was selected for each of the MCCs to be installed isolating the DNET networks to each room. The maintenance shop was selected as the location for the small panel to house the PLC and Panelview given its central location in the plant. This minimized the trunk length of the DNET cables.
The HMI was designed with snapshots of the composite floor plan of the plant to give a reference for location in the facility. An animated fan graphic was placed on top of the floor plan with the supply or exhaust designation and number of the unit. Each fan had a popup screen for status and control so parameter files were used in the FactoryTalk View ME development to minimize screens. Since there were nearly 50 fans in the plant to be added to the system over time, a User Defined Data Type (UDT) was built in the RSLogix5000 software that included all control, status, features and settings the plant needed for a typical fan. This made the development of the code or the addition of future fans quick and easy.
The temperature probes were a good distance away from the main panel, so to minimize installation and wiring costs, a wireless unit was selected from Banner. The receiver or gateway was installed at the main panel to communicate to the sensors. The temperatures were used in the code to automatically activate certain fan pairings and the status was displayed on the HMI in the maintenance shop.
Results
Two new MCC’s were installed with buckets that only included indicator lights for on/off status eliminating personnel interaction. Wireless temperature probes we installed in specific areas to control on/off timing of sections of fans and a special pairing list was developed by a 3rd party to properly group the appropriate exhaust and supply fans together to manage air pressures in the plant. The plant now has control over the air flow in the plant and has a visual aid on the PanelView indicating what the zone temperatures are and which fans are running.