Let’s continue with servo drives to see how the new solutions deliver significant advantages to end users, OEMs, and system integrators. In the past, contactors were needed to turn these drives off -- literally cut the power to shut them down -- which can cause all kinds of problems. When you bring the system back up, will it know where it was when it shut down?
With the built-in safety functions, a command is sent to the drive, allowing it to shut down in a controlled manner. It can either perform a safe stop or a safe motion function. It can do different aspects of turning off that drive or motor. Moreover, when it comes back on, it knows exactly where it was, which it wouldn't if power to the entire drive had been cut. Now we are able to bring it down and up in a safe manner.
For the end user, the benefits of the integrated approach are fourfold:
- Improved control system reliability;
- Increased uptime;
- More efficient shut downs and start ups;
- Optimized performance.
The harmonization of international safety standards, including IEC 61508 and ISO 13849 in the European Union, makes it easier to select an appropriate safety integrity level (SIL).
An integrated safety and control approach provides better visibility into the functions than separate systems perform; because the people managing, monitoring, and operating the system only need to learn one system, time and money is saved, and safety enhanced.
For the OEM and system integrator, if safety and control systems are integrated, there is no more second-guessing about whether communications are going to work with a particular device. For instance, if there are two products from different manufacturers, many problems can ensue. Just integrating the safety system into a control tool could be a major problem.
Seamless communication is an advantage of safety and controls converging in a complete package. It reduces manufacturing and engineering time. And it probably reduces the wiring time as well, because these new systems are designed to go together so there is no need to run individual wires to relays and contacts. All this will save time and money for both OEMs and integrators.
Standards are catching up
Historically there has been a difference between Europe and the US in the application of safety standards. In Europe, the responsibility fell most squarely on the OEM, while in the US end users have covered it. This differentiation is likely to diminish as stronger standards emerge. As often happens, technology has moved faster than standards are developed and approved, so standards are usually playing catch up. But progress is being made, with globalization as a key driver.
The globalization of manufacturing makes it imperative for OEMs to incorporate safety standards into their products. These must be globally accepted, but also flexible enough to be incorporated into existing systems. Safety system flexibility determines the ability to integrate with an existing infrastructure. This is especially important to users who need to integrate safety systems into plants with older equipment that fails to meet current safety standards.