30 Sep Managing Mechanical Equipment for Energy Efficiency
Posted at 15:20h in Energy Efficiency
Machine control designs are evolving in order to integrate the best practices in energy management. These steps include measuring, monitoring, controlling, and optimizing energy use to minimize energy consumption. Energy management does not require a task force to implement. It can be done from the ground up by teaching employees the best energy management practices.
The following are the measures to be implemented:
- Measuring and Monitoring – Electrical power usage is always specified on the nameplate, but this number is typically a worst-case usage estimate, and the actual energy demand will vary depending on the application of the equipment. The best way to measure and monitor this dynamic demand is to use a power meter. A power meter has the ability to measure the actual power consumed at any point in time so the power usage for each operating mode of the machine can be determined. Power is measured during all parts of the programming process to better determine when energy consumption is the highest and to identify possible areas for improvement. Monitoring power can also point to processing and scheduling problems that cause unnecessary energy usage. For example, heating up an oven for 30 minutes to reach a stable operating temperature and then only running it for an hour of production is not as efficient as planning for a longer production run. Power measurement information can be used to reduce energy usage and expenses.
- Power monitoring details – A variety of equipment is available to provide power monitoring. Voltmeters and handheld clamp-on ammeters can be used to measure a machine’s main power and auxiliary equipment energy use. These manual measurements require the opening of a control enclosure, measuring the power, and then recording the collected data. This data must then be translated to approximate power usage by multiplying the voltage by the current. For accurate, real-time energy-consumption power measurement, a power meter is typically connected just downstream of the machine’s main disconnect. Modern power meters are panel-mount devices capable of measuring true power usage in real time, transmitting this measured data to higher level controls, and monitoring systems via a digital data link such as the Ethernet. Measuring actual ac and dc running current can also provide valuable information. This is especially important when measuring distorted waveforms found on variable frequency drive (VFD) or silicon-controlled rectifier (SCR) outputs, or on linear loads in electrically noisy environments where a true RMS value is required.
- Design for energy efficiency – There are many ways machine design affects efficiency. Something as simple as supplying excess voltage to the machine can waste energy. For example, many machines need 480 V ac to power motors, but others do not. If no machine equipment requires this high voltage, a step-down transformer will be needed to reduce a 480 V ac supply to a typical control voltage level of 120 V ac. This transformer is not 100% efficient, resulting in losses of up to 5%. Most industrial facilities will have a variety of voltages available, and machines with equipment requiring 480 V ac power should be designed to accept power at this voltage. In an application where a pump typically operates at a low-flow rate, controlling motor speed with a VFD will result in much lower energy costs when compared to running the pump at full speed and throttling flow with a control valve. A review of pump affinity laws shows that a 50% reduction of motor speed results in a 75% reduction in power use. If less work is needed, then less work should be done, particularly in situations such as these where the amount of energy used decreases much more rapidly than the amount of work performed. Limiting the pressure of a pneumatic system can also help improve energy efficiency. Retro-Commissioning and Energy Audits are also great ways to improve energy efficiency.
- Turn data into actionable information – Monitoring power or true RMS current on a machine can help with understanding machine metrics such as overall equipment effectiveness (OEE). This monitoring helps identify and eliminate wasteful practices, reducing unnecessary usage. A first step is collecting real-time data to create a baseline of current power consumption. Analysis of historical machine-power usage data provides useful statistics when compared over time with baseline machine-idle power and running power. Without this historical data it is difficult for plant engineers or management to know where to start or to understand where energy-efficiency techniques will have the greatest impact. With the proper software and networking, this data can also be pushed to operators, engineers, and management in a variety of ways. Management may see the energy-efficiency data on a report analyzing machine efficiency.
- Effectively use lighting and HVAC controls – Facility managers can reduce energy waste by effectively using control solutions to improve the efficiency of lighting and HVAC systems. No matter the technology, if lighting remains on in unoccupied areas or in rooms fully lit by natural daylight, energy is being wasted. One of the most common types of lighting controls are occupancy sensors, which turn lighting on automatically when they detect motion and off when the area is vacated. Sensors can be installed in various ways—wall-mount, ceiling-mount, corner-mount, or on the fixture itself. In areas where enough ambient light is available, automated daylight harvesting systems can read ambient light levels and raise or lower artificial lighting levels to maintain a base level of illumination.
- Retrofit existing building systems – There is significant opportunity in retrofitting older, existing buildings through the modification of building systems to be more energy efficient. Project Drawdown reports that, “As much as 80% of the energy consumed is wasted—lights and electronics are left on unnecessarily and gaps in the building’s envelope allow air to seep in and out.” The retrofitting process is most effective when companies limit the scope of their retrofit to a few broadly applicable measures and roll out a sustainable technology investment bundle across their portfolio. By bundling measures, planning for, and installing new equipment and technologies at the same time, companies can better account for the interactions between measures.
The Cotocon Group have extensive experience in guiding organizations through the retrofit process. We have consulted various organizations in cutting down their energy costs with the help of Retrofits.