Identifying power quality issues

Is your automation problem really a power quality problem in disguise?

By David Paul October 7, 2014

Do you have production losses or shutdowns in your plant attributed to the automation system? Do you have automation problems attributed to software “bugs” and other software anomalies that happen at random? Does your automation system experience excessive or high rates of hardware failure in components such as PLCs, power supplies, variable frequency drives, and communication devices? Many facilities attribute these costly failures and production losses to either poor vendor hardware and/or poor software programming practices. Many plants simply write off these excessive costs “as a cost of doing business,” and just continue to replace failed hardware and reset the software. These issues should not be accepted.

Many of these automation problems are symptoms, which have their root cause in the electrical power system serving the facility. The analysis of these problems requires a holistic approach as there is an interaction and relationship between the electrical power system and the automation system components. Unfortunately, power system engineers generally don’t understand automation, and automation engineers don’t have a good working knowledge of electrical power systems. It may take both these engineers working together to find a solution.

Power quality problems may originate in the facility itself or come from the serving electric utility. The collection of actual power quality data is an essential first step in establishing a root cause of any power problem. Many utilities will assist their customers by providing power monitoring for 1 to 2 weeks as a no-cost service for their customers to assist in resolving these problems. The real key to finding a permanent solution is finding a partner that can analyze and interpret the collected data. The consultant must have a thorough understanding of both the electrical power system and the control system hardware.

Power quality problems that can affect the control system include sags, swells, brown outs, and black outs. Control system problems that result from power quality issues can include PLC processor faults, I/O faults, communications system interruptions, and VFD faults. These are the most common issues but are certainly not an all inclusive list of power or control system problems that can be caused by power quality problems. There are multiple solutions for these power problems, but there is no one-size-fits all solution. Many suppliers claim to have a solution to power problems, and their solutions may work well in some cases and be completely ineffective in others. That is why it is important to work with a consultant who starts with actual collected data, determines a root cause, and views the power system and control system problems holistically. It is also important that the consultant be solution agnostic so best solution is recommended, not just the one the consultant has existing relationship with. There are many different technologies and solutions available to correct power quality issues, choosing the right one has the potential to lower costs and increase production. The wrong one expends precious funds and leaves the problem unresolved.

This post was written by David Paul. David is the engineering design manager at MAVERICK Technologies, a leading automation solutions provider offering industrial automation, strategic manufacturing, and enterprise integration services for the process industries. MAVERICK delivers expertise and consulting in a wide variety of areas including industrial automation controls, distributed control systems, manufacturing execution systems, operational strategy, business process optimization and more.