The use of wireless devices in industrial applications has increased over recent times, particularly for applications involving machine movement. Wireless limit switches are not new, but those offering battery-free performance have become a game-changer.
They simplify machine communications where cabling is difficult, expensive or unwanted. They also lower installation and maintenance costs by doing away with long control cable runs to improve system uptime.
The transmitter electronics used in wireless limit switches need little energy for communication and harvest induced power from the movement of their mechanism. This means they operate reliably without the need for signal cabling or batteries. Schneider Electric has accumulated years of field-based data to show wireless limit switches provide the same performance as wired switches.
Correct implementation
For most installations, engineers have to account for connected cables’ physical presence and pathways: wireless is different. Those working with wireless signals understand and account for the loss of a wireless signal that can happen when it passes through certain materials. When configured, signal loss is roughly only 2%. This makes it comparable with the loss of signal experienced through standard cable connection defects, breakage or wear.
Wireless switches contain a transmitter, whereas cable connected switches do not. The transmitter aerial mounts inside the limit switch to avoid damage. New wireless limit switches offer standard or miniature formats. Thus, installing a wireless limit switch poses no more damage risk to the limit switch body than installing a typical cable-connected version. Furthermore, because Schneider wireless limit switches come in identical body formats to wired switches, updating existing installations is straightforward.
The major risk factor affecting the cable connected device performance is wear or damage to the cable itself. This risk increases as the length of the cable increases. It increases further in high traffic areas or for those using flexible cables. Other factors can include a machine causing cable movement, inclement weather or other environmental factors.
Benefits of wireless limit switches
Once commissioned, the only risks to wireless limit switches are external factors that may affect the signal itself. Assuming the installation took into consideration the known attenuation factors, then wireless signal disruption rates are almost the same as cable signal failures.
Applications
Any application using conventional limit switches can be converted to wireless operation without a problem. But most mobile applications will benefit by having wireless limit switches attached to them. For example, AGVs, transport tracks, linear robots, machine tools, rotating components, cranes and other mobile devices. The wireless limit switch eliminates costs associated with potential cable damage and maintaining frayed and worn cables.
Globally accepted technology
Telemecanique Sensors’ battery-free XCKW limit switches use a 2.4GHz frequency using Zigbee universal communication protocol. This standard gives them worldwide acceptance.
Using this frequency allows transmission over a large area for greater flexibility of installation locations. It is ideal for distances of up to 100 meters in the line of sight or 25 meters in a factory environment. Installing repeating antennas allows an increase in these distances.
Cut the cabling expenses, cut the battery expenses, and cut the maintenance times, whilst maintaining the reliability and efficiency of traditional limit switches. Find out more here.
