UPS on the front line
Computers in industrial plants and other types of technical operations have moved to the production floor. And with millions of dollars at stake in guaranteeing near-absolute power reliability for production lines, UPS manufacturers have been tasked with creating hardy systems that can withstand the extreme environments of manufacturing facilities. Several UPS products have come on the market in recent years to accommodate these requirements.
“With computers in much harsher and hotter conditions, changes in UPS design were necessary,” said Richard Smith, P.E., a consulting engineering based in Indianapolis. Unlike the systems used in a typical commercial facility or data center, an industrial UPS calls for a consideration of extreme environmental factors: temperature, humidity and chemical and dust exposure.
“Because most plants do not operate under ideal conditions, electrical system designers must use alternative %%MDASSML%% and often more expensive %%MDASSML%% approaches to solving the hardy UPS problem,” said Smith. And there are other factors that come into play for industrial UPS systems: cramped locations that are hard to access and have inadequate airflow; or ambient air that degrades the components. Naturally, the additional features required to protect a system against all these threats adds cost.
But first, to get an idea as to which types of equipment are suitable for the production floor, a quick review of UPS technologies is in order.
A UPS primer
One can categorize UPS systems in a variety of ways, but generally, these systems have three basic configurations. Which type is implemented depends on the level of power reliability required. The lowest in price is the passive standby UPS, which protects against loss of utility power, sags and surges. The next step up is the line-interactive system, which also shields a facility against power anomalies such as over- and under-voltages. Finally, an online double conversion UPS goes even further, blocking line noise, frequency variations, switching transients and harmonic distortion. It does this by constantly regenerating the sine wave serving the load by comparing output waveform with a perfect digitized sine wave. This is sampled and corrected many times per cycle. Needless to say, given the critical nature of industrial process equipment and controls, the production floor requires this last type.
UPS topology is also analyzed with respect to the power sources. With respect to the UPS system’s dc power, once again, three basic types are available: sealed-cell batteries, wet-cell or flood batteries and rotary flywheel.
Batteries become a crucial issue in the industrial facility. Commercially available UPS products have a typical temperature operating range between 32 degrees F and 104 degrees F, with a 5% to 95% non-condensing relative humidity. Most batteries used in conjunction with UPS systems are also typically designed for operation at 70 degrees F. And a general rule of thumb has it that batteries lose half their life for every 10 degrees above 70 degrees F and half their output for every 10 degrees below 70 degrees F.
“In considering the options, one user could have used a standard, commercially available UPS, rated at 10 kVA, to satisfy their power requirements,” said Smith. “Only problem was that the batteries would be in a 90-degree F environment.”
As UPS has followed computers onto the shop floor, manufacturers have solved the heat problem by bringing batteries into the UPS enclosures, which functions as an environmentally-controlled electrical room.
What follows is a description of some of the latest offerings for industrial UPS and a few examples of their implementation.
Staying on the line
Other essential features of a UPS in an industrial setting include:
Multiple and simultaneous communication ports
An automatic internal bypass and a manual maintenance bypass
Continuous sine wave output to allow full compatibility with a wide variety of power supplies
Power-factor-corrected input to reduce reflected distortion while optimizing utility power.
A lot of the issues depend on where in the world the power is generated. Buffalo-based Crandall International manufactures precision packaging machinery for the food, chemical and petroleum industries. The company’s gravimetric filling machines incorporate advanced microprocessor-based digital electronics connected to a precision digital scale to ensure the liquids are filled to the exact amount required. These machines are sold worldwide, and their sensitive electronics can be unreliable in an environment with extreme utility power problems.
All models rely on an electronic load cell with a digital indicator, which features a meter containing a microprocessor-based PLC board. The ‘brain’ of the system’s weighing mechanism, the PLC board is very sensitive and requires a steady voltage source (Fig. 2).
Several years ago, when Crandall International began selling new models to international customers, it started to experience failures of the scale controller, especially in locations in Africa, South Asia and Latin America.
“I remember sitting in an office in Kenya and noticing that while the afternoon heat wore on, the office lights became very dim,” said Keith Crandall, president of Crandall International. “Then, without warning, the lights would turn very bright. I asked what was going on and was told that the electrical system could not provide sufficient power during maximum usage, causing voltage drops. When large consumers of electricity shut down for the day, the voltage would momentarily jump up to an over-voltage state.”
It was obvious to Crandall that the problem with his filling machines was fluctuating voltages. All the equipment failures had been in lesser developed countries with poor infrastructure. Falcon Electric, Irwindale, CA, provided an online double-conversion UPS systems as a solution.
“Cheaper off-line or line-interactive UPS could help, but only by reacting to the under or over-voltage condition. After 4 to 30 milliseconds, off-line and line-interactive UPS systems change winding taps on an internal transformer in an attempt to grossly regulate (8% to 12%) the polluted utility power. These designs would pass through many power related problems, including high-voltage transients, frequency shifts and short duration voltage dropouts directly through to the meter’s sensitive electronics,” Crandall said.
“Ever since we’ve been shipping online UPS with our systems, or recommending a true online UPS to the customer, the problems have vanished,” said Crandall. “We recently sent a system to Ecuador and are preparing a unit that will be sent to Kazakhstan. I have peace of mind that power problems will not bring the filling system down.”
As UPS devices have moved to the production floor, manufacturers have continually adapted their systems to the harsh realities and confined spaces of the manufacturing environment. Industrial purchasers of this type of equipment need to consider carefully the operating environment, the robustness of the system and %%MDASSML%% last but not least %%MDASSML%% total cost of ownership.
A UPS system for a data center might have a lifespan of five years, but industrial UPS are specified with a 20- to 30-year life expectancy. The initial cost for a hardy UPS system for manufacturing environments might be greater, but long-term return on investment is ensured.
The Bottom Line…
Design changes in uninterruptible power supply systems have been driven by harsher plant floor conditions and a greater reliance on UPS to protect computers and electronic sensors.
UPS systems are getting smarter, able to conduct self-diagnostics.
Power quality correction is an important value for UPS systems, especially in places were power quality from utilities may be an issue.
Scott Siddens is senior editor for Consulting-Specifying Engineer magazine.
NEMA publishes MCCB standard
Describing the various kinds of molded-case circuit breakers, their features and associated accessories, NEMA has published “AB 3-2006, Molded Case Circuit Breakers and their Application,” which replaces AB 3-2001.
The standard is intended to help users select and apply MCCBs in electrical systems up to 600 V. It also explains specific purpose categories, construction variations and NEC requirements, and provides selection criteria for main, feeder and branch circuits; load requirements; time-current curves; selective coordination; series application; ground fault protection; and arc fault protection. It also provides information on UL 489 requirements for listed, recognized and classified circuit breakers.
AB 3-2006 may be downloaded free, or a hardcopy purchased for $75 by visiting NEMA’s website at
Crackdown on counterfeiters
Counterfeit products aren’t limited to bootleg DVDs or Gucci handbags. The recent settlement of a lawsuit took more than 100,000 unsold counterfeit circuit breakers off the market and forced the distributor to recall almost 162,000 bogus circuit breakers.
Deerfield, FL-based electrical distributor Specialty Lamp is permanently banned from selling or distributing Square D products after a Dec. 7, 2006 settlement of a lawsuit against Specialty Lamp. On June 14, 2006. the company was sued in U.S. District Court by Square D, which claimed that Specialty Lamp was selling counterfeit circuit breakers bearing Square D’s QO trademarks and copying Square D’s designs. Specialty Lamp claimed that it did not knowingly sell counterfeit Square D circuit breakers.
But on Aug. 2, 2006, Specialty Lamp agreed to an order that barred the company from selling any more lamps with the counterfeit breakers and from destroying any of the documents relating to the purchase of the circuit breakers. After inspecting the company’s inventory, Square D determined that all of the 100,754 circuit breakers in Specialty Lamp’s possession were counterfeit.
Specialty Lamp’s records show it purchased the counterfeit Square D products from Specialty Lamp International Colombia, International Light, Inc. and Victor Bonilla. The counterfeit breakers were imported from Bogota, Colombia. Specialty Lamp denied any affiliation with SLICO, and Square D officials said they added SLICO, International Light and Bonilla to the court cases.
Specialty Lamp notified the U.S. Consumer Product Safety Commission that it sold 161,900 counterfeit Square D circuit breakers and is in the process of recalling those breakers.