In lift station controls, HMI stands for “Human Machine Interface” and describes the technology used for an operator to interact with the mechanical and electrical aspects of a lift station system. Romtec Utilities believes that one of the best practices for panel design is to apply a quality HMI on a reliable and flexible programmable logic controller (PLC) platform. Configuring the control panel with an HMI and PLC will give lift station operators access to the full potential of the lift station controller.
The primary benefit of the HMI is the interface itself. Romtec Utilities will typically recommend a programmable HMI with a large touchscreen for advanced controls. Touchscreens are essentially ubiquitous in several technology applications, and they are becoming increasingly common for HMI displays. Installing a large programmable touchscreen interface will provide the controller with the best available technology. It also provides any type of information required for a pumping system, such as flow or pressure metering.
With a flexible PLC platform, the touchscreen can be programmed to meet the needs and preferences of each operator or application. For example, a lift station operator might refer to the collection basin as a sump, pit, wet well, or basin; let’s say “pit.” When the HMI and controller were purchased, this operator told the manufacturer that everything should say “pit.” Five years later, the operator has retired and the new staff only uses the word “sump.”
With a programmable HMI, ten minutes of simple programming will provide the new staff with an HMI that they can easily understand. They can change the color of the buttons, which functions are password protected, or any other area they see fit. The programming language is straightforward, and even without an in-house programmer, a capable local programmer can typically make any required changes.
The advantages of touchscreen HMIs on PLCs is commonly weighed against the option of pre-engineered (propriety) controllers. Typically on these HMIs, touchscreens are small, and changes can only be made by a technician from the manufacturer. That means you are subject to their schedules and their prices. The manufacturer may also choose to discontinue the model after a few years, eliminating the possibility of reliable support.
Beyond the appearance and functionality of the HMI, the full capabilities of the controller can be better accessed through a touchscreen HMI on a flexible PLC platform than with a proprietary controller. A programmable HMI can offer the ability to add a pump or change the level sensing device to the system controls.
If the manufacturer of a proprietary controller only provides a small, digital readout with push-buttons for basic controls, you’re stuck with those options or will have to pay the manufacturer to unlock more. If you have a large, touchscreen HMI on a flexible PLC platform, your controller is only limited by the skills of the programmer and the capabilities of the hardware. This gives you the best interface and control option for meeting current needs and possible future needs.
Romtec Utilities will typically encourage customers to investigate this method of panel configuration because it will yield better results for most pump and lift station applications. It is Romtec Utilities’ goal to provide a reliable, robust, and long-term package lift stations for every customer, and a programmable HMI on a reliable and flexible PLC panel will achieve this goal for any pumping scenario.