Intelligent Power Supply with Remote Standby
8 July 2022
Conveyor systems are widely used in manufacturing industries, as well as in warehousing management and materials management. High numbers of cycles and smooth operation require a lot of sensor technology, ranging from safety sensors to protect processes and people, to identification systems and object detection technology, to sensors used for measuring object distances or volumes. As different as the measuring devices used for these purposes are, they have at least three things in common: They require a 12–24 V power supply, they are only needed when the conveyor system is running, and they lack conventional on/off switches.
Nor would it be a good idea to turn hundreds of RFID systems, photoelectric safety sensors, optical identification sensors etc. on and off manually. These loads are switched in strands via their power supplies. When the last shift ends or the weekend is almost here, the conveyor system shuts down, and with it the required power supply units for the sensors. However, if a conveyor or transport system is only idle for an hour or two, the usual approach is to simply keep the safety, positioning or identification systems energized.
An Environmentally Conscious Company
This exact approach, while convenient, has become a thorn in the side of some companies: “One of our large customers in Japan operates extensive conveyor systems at several locations,” reports Yasunobu Ohta, Regional Sales Manager at WAGO Japan. “Once a day, they halt production for the one-hour lunch break; the belts are idle, but they continue to power the sensors. The management saw this as an opportunity to save energy.”
Ideas were gathered in an internal optimization initiative, and it quickly became clear that the auxiliary sensor shutdown process would have to be coupled with the conveyor systems’ main switch: “It would have been inefficient to manually shut down each of the 20–24 V power supply units and then turn them back on one by one after the break,” Ohta continues. They were finally able to find an elegant solution using WAGO’s Pro 2 Power Supply. This intelligent power supply unit has a digital input and output that can be used both to put it in standby mode and to put it back into operation.
An Automated Wake-Up Call for Everyone
When the coupled controller detects the conveyor going into manual stop, the connected Pro 2 is put into standby mode through a DO signal. Since this signal can be sent to other power supplies in a cascade, the controller does not need to be wired to each power supply unit separately; the DO signal is passed from Pro 2 to Pro 2. “When the main switch is used to stop the conveyor, all the 24 V power supplies automatically go into standby mode, and they’re all switched back on as soon as the system is running again,” Ohta reports. The intelligent WAGO power supplies’ configurable switch-on delay is used to prevent all the DC power supply units from switching on at the same time and causing load peaks.
The coupling between the central switch and the conveyor system means there are no further steps for the staff to take into account. This prevents safety violations and process disruptions caused by accidental failure to switch sensor systems back on. Therefore, this solution offers not only considerable potential savings, but also a high level of user-friendliness.
This application is easy to implement, and in many companies, it can achieve greater energy savings than might be expected at first glance: “Since there are many different sensors, the amount of energy saved depends on the specific system,” explains Ohta. He continues: “Some sensors require only a few milliamperes, others several hundred milliamperes. But in any event, the large number of systems used leads to noticeable potential savings.”
Let’s look at an example calculation. If 100 devices draw average current of 100 mA and are powered with 24 V, one hour of operation requires 240 Wh of energy. Over 260 business days, this totals 62.4 kWh/a. If 800 mA is used instead of 100 mA, the energy input per year amounts to just under 500 kWh – that’s an amount that can be saved without much effort.
Even a large number of seemingly small steps can save a large amount of energy overall, and thus significantly reduce carbon emissions. In any event, a solution that both saves companies money and protects the environment is always welcome. Sometimes all it takes is an idea and the right technology, such as the WAGO Pro 2 Power Supply.
The WAGO Pro 2 Power Supply: Control cabinets are undergoing a transformation, with both quantity and quality demands constantly increasing. Greater networking, rising energy costs and growing customization require smaller, more economical, faster and more flexible solutions in control cabinets.
