Feature: Software
[Image: Adi Goldstein for Unsplash]
Protecting microprocessors and avoiding software
confusion By Jeff Edwards, CEO, Energy Control Systems
T
he role of microprocessor-based control systems in industry spans the scope of hardware and soſtware solutions, from back-office IT systems and telecommunications to factory floor automation control systems. If engineers want to maintain productivity, they must do more to protect all this
equipment from electrical disturbances. All the electrical equipment in a facility, from IT systems to factory
automation equipment like PLCs, need protection from power disturbances. Back-up generators can keep systems operational during a utility outage, but they take time to start up, and provide no protection from power spikes and other electrical disturbances. Traditional surge suppressors can protect infrastructure from
electrical disturbances that occur due to power quality issues, such as power spikes and brownout conditions. However, these devices are not built to handle all forms of electrical disturbances. Tere has always been a need for lightning surge arrestors at the mains but the industry has evolved beyond that. Te focus needs to be more on microprocessor-based equipment to prevent soſtware confusion. Today we use equipment fitted with microprocessors running at
gigahertz speeds, so the smallest disturbance can negatively impact productivity. Oſten these disturbances go unnoticed by both human operators and traditional surge protection equipment that will only clamp events high above or far below the sine wave. However, extensive duration of these events could be costly.
Power fluctuations Introducing equipment to the mains or utility supply, such as variable frequency drives (VFDs), means that voltage rarely acts as we would expect. For example, if we imagine the sine wave as binary code in terms of ones and zeros, we expect power at peaks and valleys to be one and any crossings of the wave to be zero. However, power disturbances triggered by power quality issues or equipment such as VFD’s mean that this will not occur. Instead, in six pulse drive operation, the transient occurs six times per cycle, two times on the wave. Voltages of 600-700V may not seem significant when they occur once, but this will happen millions of times an hour. A false zero
34 April 2021
www.electronicsworld.co.uk
crossing like this causes microprocessors to trigger prematurely. Electrical disturbances can also occur without lightning – we have
found that 80% of electrical disturbances come from inside the facility. Tese smaller disturbances may go unnoticed at first but may also cause unexplained soſtware confusion and errors. However, engineers will find that if they restart the system, it will return to normal production. A traditional surge protection device measures and clamps events
that occur above and below the sine wave are the maximum and minimum operating voltages. Until voltage exceeds those points, the surge unit is idle, but once a voltage spike or transient exceeds that level, it will clip those transients.
Attenuation To eliminate all power-quality problems, our engineers created a frequency attenuation network tuned transient filter that monitors the entire sine wave through 360 degrees, so that if an event occurs at any point, it can be attenuated, smoothed out and eliminated, thus assuring much reduced downtime on all microprocessor-based equipment. We have developed a unique technology in our approach to dealing
with electronics and microprocessors. If an 800V spike is injected into a SineTamer unit (see image below right), the output is 14V maximum, while a 0V input spike is practically undetectable at the output. If the transient peak is around 80-125kHz, we can smooth it out.
ECS008 - SineTamer
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