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Variable Transformer Questions
Where can I buy replacement brushes and other parts?
You can replace most of our parts through your local distributor (visit our Where To Buy replacement brushes and parts section) or one of our national distributors, such as Allied Electronics or Newark Electronics.
If you have trouble finding the part you need, call the factory direct at 866-261-1191 and a customer service representative can help you order the part(s) you need.
Where do I find replacement fuses?
Fuses used in the variable transformers are usually those from the major fuse manufacturers. The part number and amperage rating can be found on the fuse itself. If not, please contact the factory for assistance.
Can I buy your products over the internet?
Many of our standard products can be purchased over the internet, through our distributors that offer on-line shopping. (See our Where To Buy section for a list of distributors that offer this service.) Some of our products, however, are more complex than an on-line purchase will allow. In that case, you can contact a distributor directly or contact the factory to discuss your needs.
Can I get CAD drawings to import into my specifications?
Yes, for most of our standard products. We have made PDF files of our engineering drawings available for download.
If the drawing you need is not available, you can contact our Engineering Department directly by calling our toll free number (866-261-1191). Actual CAD drawings can be emailed to you directly. Just call one of our sales engineers or send us an email with your name, address, phone and email address.
Does Staco Energy offer a warranty on variable transformers?
Yes. We offer a full one-year warranty on all variable transformers.
How long should a variable transformer last?
When used within the specifications of the unit, the variable transformer should last for many years. The most common reason for VT failure is either from high voltage or high amperage that exceeds the rating of the unit. The second most common reason is failure to replace the carbon brushes on a periodic basis. The brushes should be visually inspected at least once per year. Inspection should include abnormal wear and/or chipped or broken carbons. Replacement brushes for most models are readily available.
Can I use a VT at different input voltages than those shown in the specifications?
Yes. Variable transformers are capable of handling voltages from 600 volts down. For special input voltages, contact the factory to assist you in specifying the correct unit.
The 501C Variable Transformer has 5 terminals.
The 501C has been designed to be panel mounted or bench mounted. If mounted to the back of a panel, then the neutral connection is terminal 4, if bench mounted, neutral then becomes terminal 1.
It is also designed to yield a "boost" voltage, meaning you can get 140 volts output with a 120 volt input. These terminals are 2 and 5. For example, if back of panel mounted, terminal 4 is neutral and terminal 5 is hot. With 120 volts applied across terminal's 4 and 5, the output between terminals 4 and 3 will be 140 volts. This gives voltage increase in a clockwise direction.
Does Staco Energy manufacture "special" variable transformers?
Yes. Staco Energy manufactures variations of our standard catalog offering. This group of units is referred to as “PPS” units. PPS stands for Provider Power System. We have designed and built many of them to meet special requirements of our customers, including A.O. Smith, Schneider Electric, McQuay, General Electric, and other Fortune 500 companies.
How are the sizes of UPS determined?
Typically, a UPS has a VA or kVA (VA ÷ 1,000) rating. This is the maximum number of Volts x Amps it can deliver. The VA rating is not the same as the power drain (in Watts) of the equipment. Computers are non-resistive. A typical PF (Power Factor: Watts/VA) for workstations may be as low as 0.6, which means that if you record a drain of 100 watts, you need a UPS with a VA rating of 167. Some literature suggests that 0.7 may be a good conversion factor, but this depends heavily upon the machine being protected.
How can a UPS help me?
A UPS has internal batteries that supply power to the protected equipment even if the utility power is interrupted. It also protects any equipment plugged into it from sags, surges, brownouts and some degree of spikes. It acts like a surge protector, voltage regulator, and battery backup all at the same time.
What does a UPS do?
Traditionally, the main reason for purchasing a UPS is to keep power to equipment in spite of a blackout. It used to be primarily for computer and telecom equipment, to give users time to shut down the equipment without loosing data or damaging the equipment. Now, however, UPS are used to protect any equipment that can suffer data loss or damage due to power outages and voltage fluctuations, such as hospital and medical diagnostic equipment, HVAC systems, elevator systems, industrial robotics and automation systems, and more.
How long can equipment on a UPS keep running after the power goes out?
That depends on how large your UPS system is and the type of equipment it is protecting. Some with extended battery packs and/or hot-swappable batteries can run virtually unlimited times. However, if you want extended run times, you may want to look at a backup generator instead of or in addition to a UPS. Usually, a UPS is designed to run from a few minutes to about fifteen minutes with its internal battery system.
How important is the UPS output waveform?
That's a good question, and worth debate. One school of thought holds that one should always run equipment on the best approximation of sinusoidal input that one can, and that deviations produce harmonics which may either be interpreted as signal if they get through a power supply, or may actually damage the equipment.
Another school holds that since almost all computers use switching-type power supplies, which only draw power at or near the peaks of the waveforms, the shape of the input power waveform is not important.
Who's right? Both probably are. Output sine wave may not matter to some equipment, and can cause untold damage to others. True sine wave output is probably worth the extra money, especially for on-line UPS systems that continually provide their waveform to the protected equipment.