The "Common Power Problems" guide will give you a clear understanding of the causes and effects of specific power problems and of the most effective solutions.
Common Power Problem
The most expensive solution is not always the right solution for the problem. Both correct identification of the power problems and your company’s needs should be addressed to ensure an accurate assessment.
Here also is where the use of a qualified power auditor can prove to be invaluable. The auditor will not only identify power quality issues within your company, but will also help you assess your specific needs. The auditor can then put together a recommendation that meets your needs without unnecessary expense.
There are five basic categories of solutions to some of the power quality problems, each having different capabilities, strengths and weaknesses. The following is a list of these categories with links to more information on each one.
Power Quality Solutions
4.Uninterruptable Power Supplies
quickly that they do not register on normal electrical testing equipment.
Surge suppressors or surge protectors are the most basic form of power protection. A surge suppressor is often used to shield
important, but less critical or highly senstive equipment. It is also used as a complement to more comprehensive power protection solutions.
They are passive electronic devices that protect against transient high-level voltages.
Transients are often the cause of “unexplained” equipment problems, computer lock-up, data loss, and other “gremlins” inside a facility.
Transient voltage surge suppressors can be incorporated into voltage regulators, power conditioners, and UPS for added protection.
Depending on the components involved, surge suppressors offer limited protection against power surges. In the case of frequent high voltage spikes, a high quality surge suppressor is a good choice. When large equipment like AC motors are turned on and off, they create large, fast voltage changes (switching transients). However, low frequency surges (slow changes at 400 Hz or less) can be too great for a surge suppressor attempting to clamp that surge.
Many businesses require voltage regulation rather than battery backup power. In those cases where backup power is unnecessary, a voltage regulator can provide superior protection with much higher electrical efficiencies than a UPS.
A voltage regulator may also be referred to by the labels “power conditioner”, “line conditioner”, “voltage stabilizer”, etc. Regardless the term used, these devices are all essentially the same in that they provide voltage regulation and one or more additional power quality-related functions.
A voltage regulator can correct and/or provide protection from power problems such as:
Sags and Dips
Line Noise and Swells
Brownouts and Surges
Power quality problems can occur anywhere, anytime. Evidence of these problems can be as obvious as electrical components that are damaged or fail prematurely or as subtle as equipment that randomly malfunctions. But, the real problem with poor power is the cost of damaged equipment, lost productivity, scraps, missed schedules, etc.
Voltage regulator applications
Power Solutions provides industrial-grade voltage regulators designed for maximum reliability in the toughest applications, including:
Power Generation & Transmission
Pulp & Paper
Medical Imaging & Oncology Treatment
Voltage regulators are also used in conjunction with UPS units for example, to extend the UPS capabilities and increase UPS efficiency, to protect the UPS, to condition the UPS bypass and to protect HVAC systems.
The Standby UPS consists of a basic battery/power conversion circuit and a switch that senses irregularities in the electric utility. The equipment to be protected is usually directly connected to the primary power source, and the power protection is available only when line voltage dips to the point of creating an outage. Some off-line UPS include surge protection circuits to increase the level of protection they offer.
In the case of power surges, a standby UPS passes the voltage surge to the protected system until it hits a predetermined level, usually around 115% of the input voltage. At the surge limit value, the unit then goes to battery. Although they do provide reasonably good protection against spikes and switching transients. However, they do not protect against sags, line noise, frequency variation or brownouts unless the battery is delivering power to the protected system.
If the UPS is forced to go to battery frequently, it can drain the battery, making it unavailable during blackouts. Since standby UPS provide only partial protection against many common power problems, they are most often used to shield a single user or less critical or sensitive equipment.
Line Interactive UPS are hybrid devices that offer a higher level of performance by adding better voltage regulation and filtering features to the standby UPS design.
Like standby models, line interactive UPS protect against power surges by passingthe surge voltage to the equipment until it hits a predetermined voltage, at which point the unit goes to battery. They provide moderate protection against high voltage spikes and switching transients, although, again, not with complete isolation.
With power sags, line interactive UPS may use a tapped transformer to provide the voltage levels needed to maintain output voltage. Essentially, the unit switches to battery to adjust the tap location at set intervals to maintain the output voltage as the input voltage falls. It will eventually go to battery full-time once the input voltage reaches a pre-selected level. This sytem offers adequate protection as long as the power sags aren’t continuously changing, which may reduce battery time. If it is frequently going to battery, you run the risk of not having the batteries fully charged for use during a power outage.
For electrical line noise and frequency variation, line interactive UPS work only when the inverter is operating and the battery is the power source, which may drain the battery during prolonged unstable conditions that typically occur during generator operation.
Ferroresonant UPS, another hybrid technology, keeps the inverter in standby mode similar to line interactive and standby UPS. The protected system, however, is powered from the utility through the ferroresonant transformer. The transformer provides voltage regulation and power conditioning for disturbances such as electrical line noise. The ferroresonant transformer also maintains a reserve of energy that is usually sufficient to power most small equipment or PCs briefly when a total outage occurs. This keeps the equipment supplied with power within most input requirements until the inverter is switched on.
However, ferroresonant UPS are not very effective against unstable frequency variations or sudden current changes. In general, ferroresonant UPS work best with most non-computer or on-critical technology, or with linear loads such as motors, heaters and lights.
Double Conversion (Online)
Double conversion UPS, often called “Online” provide the highest level of power protection and are an ideal choice for shielding hyour organization’s most important computing and equipment installations. This technology uses the combination of a double conversion (AC to DC/DC to AC) power circuit and an inverter, which continuously powers the load to provide both conditioned electrical power and outage protection. Online UPS offer complete protection and isolation from all types of power problems – power surges, high-voltage spikes, switching transients, power sags, electrical line noise, frequency variations, brownouts and blackouts. In addition, they provide digital-quality power not possible with offline systems. For these reasons, they typically are used for mission critical applications that demand high productivity and system availability.
Double conversion UPS can be the most cost-effective way to ensure comprehensive power protection. Double conversion systems provide the same benefits of a standby UPS in conjunction with a line conditioner, at a price that is lower than buying the two components seperately. However, double conversion UPS also can be the most expensive solution initially, and they require regular battery maintenance and monitoring. UPS batteries can e very expensive, and are also temperature sensitive. They cannot be placed in harsh environments.
Because of expense and sensitivity of these units, they are normally used only if there is no other acceptable alternative to 100% continuous power.
If you use a generator to backup a UPS during extended blackouts, the U.S. Department of Commerce suggests that it be rated at about 2½ times higher than the UPS it is backing up.