Q & A with Dan Carnovale, Power Quality Solutions Manager, Eaton Electrical

IEN: What are the major power quality and availability problems facing industry?

Carnovale:

Problem: The environment within various industry factories is changing. Increasingly, digital technologies and computers are being used in process controls, instrumentation, and equipment on factory floors. Also with JIT practices, the need for uptime is increasing in industries -- a momentary power interruption can disrupt production, causing hours of unnecessary downtime, resulting in lost productivity and loss of materials being processed.
Solution: This increased reliance on digital technology increases the need for power protection beyond transient voltage surge suppressors and voltage regulators. Uninterruptible power supplies (UPS) can protect equipment from a breadth of power anomalies, including outages, surges, and spikes, as well as many other hidden power problems that can impact equipment performance. Industries reliant on digital equipment need confidence that their systems are protected 24 hours a day, seven days a week from all potential power problems. Additionally, these changes we are seeing inside of factory floors are not the only concern -- problems with utility power continue to reinforce the importance of power protection. The massive power outages that hit the northeastern United States in August 2003 were an evident reminder that utility power is not always reliable. In fact, U.S. Energy Secretary Spencer Abraham indicated, in May 2004, that although upgrades have been conducted on the U.S. power grid, there are continued risks of power outages and blackouts. Traditional methods of power protection such as surge protectors and generators cannot address the full spectrum of power issues that can arise. Implementing the appropriate UPS technology with a comprehensive power protection strategy is the best way to reduce unnecessary downtime and regulate the quality of incoming power from the U.S. power grid.

Problem: Based on a six sigma quality study conducted by Eaton in support of Powerware products, 50% of UPS malfunctions were caused by battery failure.
Solution: It is imperative that any UPS purchase be accompanied by a documented, routine maintenance plan to assure battery integrity.

Problem: There are four broad problems that can impact power quality:

• Problem #1: Transients (high frequency oscillatory or impulsive voltage deviations from the normal sinusoidal voltage waveform). These high frequency overvoltages cause problems from simple nuisance operation to complete destruction/failure of power system equipment like power supplies, transformers or capacitors, for example.
  Solution: Generally, transients are best eliminated or dealt with using transient voltage surge suppressors (TVSS), also called surge protection devices (SPD). These devices are fast-acting, non-linear devices that typically do nothing during normal power system operation but then "turn on" to remove damaging overvoltages once the voltage exceeds an excessive level. Other versions of surge protection are always in series with a critical load and "slow down" or remove smaller oscillatory transients that typically cause nuisance operation.


• Problem #2: Harmonics (frequencies typically higher than the fundamental frequency, of 50-60 Hz, that are superimposed on the fundamental frequency and distort the normal sinusoidal voltage or current waveform). Harmonic currents are typically caused, or generated by, the new loads that we use on our systems today. These loads, often called "non-linear" loads, typically convert ac to dc or ac to other frequencies of ac. Loads like computer power supplies, variable frequency drives (VFD), and rectifiers draw a current that is not proportional to the 50-60 Hz sinusoidal voltage and they send higher frequency currents from the load back through the power system. When these currents flow on the power system, they create voltage drops that are proportional to the frequency of the current. For example, a 5th harmonic current generated by a VFD flowing through a transformer will cause a 5th harmonic voltage drop and will cause 5th harmonic voltage distortion. Then, since the voltage is distorted, other loads on the power system may misoperate, malfunction, or overheat.
  Solution: There are many solutions to combat harmonic distortion. Generally, you can divide them into several categories: avoidance (design the loads to create very little distortion -- low distortion lighting ballasts, active rectifiers, etc.), tolerance (design the system to "handle" the excessive current and voltage distortion -- 2X neutrals, K-rated transformers, phase shifting, etc.), or filtering (remove the harmonic currents from the part of the power system where it creates problems -- active, passive, or combination filters, etc.).


• Problem #3: Voltage variations (short-term or long-term over- or undervoltages that exceed the standard acceptable load operating level. This includes voltage sags, the most common and costly power quality disturbance, as well as short-term interruptions and full outages).
  Solution: Solutions for voltage variations include uninterruptible power supplies (UPSs), sag correctors, voltage regulators, etc. The solution must match the load requirements for response and kVA size.


• Problem #4: Grounding (the proper design and implementation of grounding methods to insure safety and reliable operation of today''s sensitive electronic loads).
  Solution: Grounding solutions are generally consultative designs whereby proven best practice methods are utilized and allow for proper operation of loads and protective equipment (fault protection, surge protection, etc.).

IEN: How can today''s manufacturers treat energy management more strategically?

Carnovale: Manufacturers are being asked to help justify power quality solutions with potential energy savings. Ironically, some PQ solution providers are deceitful in their representation of their products in saying that they will save excessive energy when in fact, they can''t or won''t, in reality. It is often left to the end user to determine the truth. An honest, simple approach to payback and use of energy-saving equipment is required.

IEN: What are the latest advances in audits? . . .

Carnovale: Significant advancements in power system monitoring have allowed companies like Eaton to significantly advance our capabilities in power system audits. These audits now address all aspects of power quality, energy management, safety (especially today''s hot topic of "arc flash"), and environmental considerations as they relate to reliable operation of power system equipment. Simplified analysis methods have been developed to determine reliability metrics to compare one power system design versus another potential design.

IEN: Retrofitting? . . .

Carnovale: Today, in our aftermarket''s support group, we have made significant advancements in implementing novel approaches to solving power quality issues. For example, adding surge protection or harmonic filters to a panelboard or MCC, by design, inherently increases the overall system reliability.

IEN: How about power supplies?. . .

Carnovale: Today''s power supplies are more often featuring a front-end power factor correction built in. Power factor-corrected power supplies offer a slightly more expensive but significantly improved operation. These power supplies correct for the load power factor and harmonics in the load itself so that add-on solutions (which are much more expensive) are not required. This also means that UPSs for these applications must be sized to handle the real power (watts) required by the power supply, and in some cases also the ability to handle leading power factor conditions when a number of power factor-corrected power supplies are supported by a single UPS.

IEN: Power quality?

Carnovale: Many new power quality solutions are being designed into the load so that the power system issues can be minimized. UPS equipment with an active front end reduces the current distortion, while improving the power factor, and eliminates the need for costly filters or oversized generators.

IEN: How and where are Reliability Centered Maintenance (RCM), web-based monitoring, embedded maintenance, and other solutions being applied in power quality/availability?

Carnovale: RCM is being used by a significant number of our customers. We have designed a program whereby a customer will do the power system maintenance as required and not on a simple time-based schedule. This is a huge savings for companies in two ways: 1) by the simple cost reduction of performing less scheduled maintenance; 2) by implementing reliability-focused upgrades with a portion of the savings that are generated using RCM.

All power quality problems require monitoring and analysis to completely understand the issue so that the most appropriate solution can be applied. New advances in monitoring have made analyzing power system problems easier, and with advances in communications, experts can help analyze problems from thousands of miles away. In addition, computer simulation tools allow consultants and end users to model power systems in substantial detail so that "what if" scenarios can be tested prior to full implementation.

IEN: What steps have been taken toward resolving safety and security concerns?

Carnovale: The NFPA and IEEE have recently pushed adherence to their latest standards regarding arc flash. Electrocution is a well-understood phenomenon and measures have been taken for workers to avoid coming in contact with live or energized parts of an electrical system. However, fewer workers understand the real danger associated with arc flash and the more damaging effect of being near a fireball/explosion that occurs when a fault happens on a power system. Far too many workers are injured or killed each year as a result of arc flash incidents. Steps have been taken by many large (and small) corporations to implement a safety program that includes the calculation of arc flash potential and the proper personal protective equipment (PPE) levels required to work on energized equipment, etc. These programs generally involve a power system study, labeling of equipment, and specification of PPE.

Industrial processes are becoming more and more dependent on clean electrical power, as PLCs, VFDs/VSDs, and computer automation are the norm. Most companies are also very concerned about market pressure and budget constraints, so they are electing to move from the high price "purely" industrial UPS solutions to solutions which are typical in the IT sector. However, the industrial engineers are still concerned about performance of their UPS selections, so they carefully choose products based upon their intended use and they require the UPS manufacturers to provide data and/or test results that are in line with their expectations. Continuing cost pressure has also pushed engineers into looking for highly efficient UPS systems to help reduce monthly operational expenses.

With many industrial processes being so critical today, we are also seeing a rise in demand for N+1 parallel redundant UPS systems. This ensures that even if one system is taken off line for maintenance, the critical processes are still protected by the remaining UPS module(s). In addition, engineers are looking for UPS systems with the capability for capacity upgrades, so they don''t need to relocate or scrap an undersized UPS and replace it with a larger UPS system.

Integration of the UPS with electrical distribution equipment is also on the rise. Using equipment designed in this fashion helps reduce the cost of the installation, which helps to keep capital expenditures down, which pleases the stockholders.

Wet cell or VRLA battery systems are still the norm; however, we are seeing more and more interest in "alternative" stored energy sources such as flywheels, microturbines, and fuel cells. Cost of these alternative energy sources is still too high to make them very competitive with batteries, and their complexity typically leads to increased risk analysis.

Most of the equipment protected has high power factor inputs, so the UPS systems need to have high output power factor ratings, typically .90 or greater. Many engineers have switched to using the UPS system kW, rather than the typical kVA rating.

Effectively managing these UPS systems and all the other intelligent process control devices has also taken a step forward as these systems need to communicate to a standard protocol (ModBus, etc.) so they can be seen by a building or process management system. The Internet has also expanded the typical process management interface, as we see industrial users using the web to view equipment status and report loss of functionality.