Time-Sensitive Networking (TSN) enables a single, open network infrastructure supporting multi-vendor interoperability through standardization and IT and OT convergence through guarantee of service.
The development of the TSN set of standards was originally conceived in order to deliver time-sensitive data to machines in a closed loop and to handle situations that arise that standard Ethernet networks cannot deal with. However, Time-Sensitive Networking also has a role to play in the reduction of the risk of accidents and in the improvement of factory safety levels.
There are common safety hazards in the manufacturing environment which can affect the health and safety of a factory worker on the shop floor, as well as negatively impact overall factory safety levels. Factory owners and manufacturers are therefore required to implement detailed safety policies in order to ensure that the risk of injury and worker exposure to harmful chemicals is significantly reduced.
Hazards such as machine failure leading to accidents and injury to workers, exposure to harmful chemicals, fire risks, toxic spills and excessive noise from machinery all need to be addressed in a factory’s safety policies and plans.
Common factory safety hazards and the potential application of TSN
1. Machinery operating in tandem
In a typical factory environment or production line, machinery or equipment is often operating in tandem – with one machine reliant on another machine for data or feedback. The standard Ethernet network can usually handle the transmission of data, however when the network becomes saturated with traffic, problems can arise in the transmission of data and interruptions in synchronization can occur.
This can lead to failure of machinery or the disruption of the factory processes, which will lead to increased hazards in the factory environment. The application of the TSN set of standards can handle situations in which additional traffic is involved, facilitating the transmission of data in a reliable manner, unaffected by dense network traffic and over longer distances than an Ethernet network can.
2. Real-time data required within milliseconds
Operations such as robot control require real-time data within milliseconds. If these machines do not receive this data in time, then this will lead to failure of the entire process and assembly line. Robotic arms, for example, have the potential to move over their base with high speed and force, so these can cause severe injury if they are not operating correctly, due to data not being received.
Ethernet connections cannot ensure or guarantee that these packets of data are transmitted in the 1µs timeframe that is sometimes needed.
Additionally, other equipment on the factory floor often has moving parts, scissors or shear action, rotating sprockets and gears. If these machines are not tightly controlled within the timeframes they are supposed to operate in, then these parts can cause harm to the factory workers that are working with the machines and expecting a certain process to take place within a specific time range.
Since the TSN standards are focused on time and TSN was developed in order to ensure that data can travel from a sender to a receiver in an expedient manner, TSN connectivity and real-time delivery of data can help avoid dangerous situations that may arise due to timeframe issues.
3. Toxic chemical spills and fire risks
In an environment such as an oil refinery, the risk of fire and toxic chemical emissions always exist due to combustible chemicals such as methane, butane and many other hydrocarbons involved in the crude oil refinery process. The typical hazards in an oil refinery, in addition to fire and explosions include asphyxiation, burns, toxic inhalation and corrosiveness.
The sources of these hazards include boilers, heaters, storage tanks, cracking units, heat exchangers and a variety of other equipment and machinery on the plant. Most refineries and plants do have alarms and sensors that monitor the risk of fire and toxicity.
The implementation of a TSN network could however, vastly improve these detection and alert systems since it can deliver the critical data to the central control unit quickly, thereby ensuring that the operators can take the appropriate action and workers are not exposed or harmed.
4. Excessive noise
Noise issues in factory and manufacturing environments are a common issue. Workers are often exposed to noise and this can lead to severe deterioration in hearing functionality over time. Workers are usually instructed to wear ear plugs, or ear defenders in order to mitigate the effects of their exposure to noise. Some factories use absorptive silencers in order to reduce the effects of noise.Machines and equipment that are faulty or have not undergone the proper maintenance can cause a situation where there is excessive, harmful noise. In a scenario like this, time is critical. The sensors installed in the factory or on the machines would pick up the increase in sound, this information would need to be delivered quickly to the servers or the Human-Machine Interface HMI. Workers could then be subsequently instructed to either evacuate the building with immediate effect or switch off the machines causing the issues.
In these kinds of situations, a TSN network would be vastly beneficial since the TSN network could deliver the data with low jitter, no packet loss and expediently.
Implementing TSN in the safety manual/safety policy of a factory
All factories, plants and manufacturers are required to develop safety plans, procedures and guides as part of their standard operating procedures.
In order to implement TSN within the factory safety plan, it is recommended that the factory supervisor first identify all potential risks and hazards associated with all the machinery and processes at their factory. The next step would be to identify all the machinery and assembly lines that need real-time critical data and the dangers associated with these machines if their data requirements are not met.
Finally, the factory supervisor would implement a TSN network and classify this in terms of data management and efficient data-delivery procedures. The factory supervisor would detail the risk alleviation associated with this network.
In terms of actual integration within the current networks, typically the TSN bridge and endpoint would be connected to an IoT gateway, SCADA system or HMI in order to be integrated into the existing information management platform of the factory. A key advantage of the TSN set of standards is that they are open, therefore interoperability is not an issue.
This would ensure that the data is delivered as needed and can contribute to the improvement of safety levels in the factory in the event of an emergency or as part of standard factory processes.
Conclusion
When asking “can TSN help factory safety?”, the answer is yes, it can. Ethernet has traditionally been the connection option of choice in many industries and working environments regarding the transmission and transfer of data over digital cables. However, Ethernet has key limitations and thus cannot contribute to the reduction of workplace hazards in the factory or manufacturing environment as effectively as TSN networks can.
The TSN set of standards offers solutions to the minimization of jitter, time-scheduling for those machines and assembly lines that require it and determinism. In addition, TSN has the potential to play a major role in the future safety procedures of factory operations and processes.
