An Overview: Selecting a Power Transformer
Today, power transformers play an important role in many critical industries including telecommunications, railroads, military installations and manufacturing facilities. This article will identify 18 key pieces of information to look at before attempting to select the right power transformer.
1. Address exactly what your transformer will do. In its simplest form, a power transformer uses electromagnetic induction to send an alternative current or voltage from one electrical circuit to another. A very basic, yet keypoint, to address in selecting the correct transformer for your purposes concerns identifying whether this device will convert an AC current to a DC current or simply transmit one DC current to another DC current.
2. Determine the largest transformer required to accommodate actual power loads. Usually, this task involves multiplying the amperes of maximum expected load current by the load voltage for a single phase. Then, most people add in an additional 20% in order to allow for additional future expansion. This extra cushion represents a safety factor as well.
3. Ascertain whether or not the transformer will be pole mounted or pad mounted, and whether it will be located inside a building or in an outdoor location.
4. Determine the maximum primary and secondary voltage and compare these figures with industry-specific standards. For example, many smaller facilities use 480 Volts as a secondary voltage.
5. How will you configure the wires? Typically, a power transformer involves 4 as the most common configuration, but exceptions exist.
6. What is the power factor and the level of efficiency? Answering these questions will require site-specific calculations.
7. What is the percentage of the power load impedance in ohms? It may be useful in answering this question to closely review the site specifications. There should be a correct match between the impedance and the power load.
8. How much will the electrical transmission raise the temperature of the system where it is installed? Do any precautions need to be taken to assist in the maintenance of optimal temperatures?
9. What are the anticipated environmental parameters in terms of the operation of the power transformer? At what height will it operate? Have appropriate access arrangements been provided to permit maintenance crews to service the equipment at regular intervals, or during emergencies?
10. What cooling mechanisms have been established? How long will the transformer operate between inspections?
11. What are the optimal location and space requirements of the power transformers under active consideration for this project? Does the use of one particular model offer any cost savings advantages over the others, all other aspects of the project being equal?
12. Will the transformer operate within an area of known seismic activity? For instance, the location may make a significant difference if the equipment on the site must withstand frequent low level seismic activity.
13. What accessories does this particular project expect to utilize? Must the power transformer accommodate the specifications for particular instruments? For example, this consideration might play an important part in the selection of a power transformer desired for use in a scientific project in which accurate readings remain important. Additionally, a power transformer used in a military capacity might need to be evaluated with these considerations in mind.
14. Does the project call for a “dry type” or a “liquid filled”? Experts caution that a dry type of power transformer should never be overloaded. If this occurs, the development of excessive heat can permanently damage insulation and cause a failure in the coils.
15. In the event of a power overload or power fluctuation, what levels of overload will each of the individual power transformer models under consideration withstand without sustaining irreparable damage? As a general rule, some power transformers will safely operate at lower rates; they don’t operate safely at higher than stated “nameplate” levels of power. Consequently, if the system sustains frequent fluctuations in power levels, it is better to obtain a more powerful than necessary power transformer that functions well at a lower rate.
16. Will the power voltage outputs remain constant over time, or will a particular power transformer likely be relocated to another site with different parameters in the future? For instance, both the United States and Canada typically operate on 110/120 volts, but in other parts of the world industrial facilities may function at levels as high as 440 to 480. Expectations about the future use of the equipment may play a role in acquisition decisions.
17. What is the best insulating system to use with the specific power transformer? As a general rule, the cost of insulating systems rises significantly with higher temperatures, and large power transformers cost considerably more to build, as a result.
18. Finally, how do each of the power transformers under consideration rate in the opinion of each of the team members? Have useful reviews from engineers been received from the use of any of these models elsewhere in a company project?
Contributed by http://abbott-tech.com/