VFD transformer rental
This post provides a brief description of our service “VFD transformer rental”. You will learn what the service is about, how it works, what is the target application etc. The contact form is located in our section Services (click here).
Introduction
Transformers are mainly used in power transmission and distribution. Medium voltage VFD usually requires an input isolation transformer as well. The reasons for such transformer are explained here [1]. Direct to line (transformer-less) grid connection is principally possible, but only for a specific grid voltage. Such option comes with many restrictions. More information about the VFD grid connection can be found here [2]. The design of a VFD transformer differs from a power or distribution transformer. The specific requirements on VFD transformers are explained here.
To summarize: Majority of medium voltage electric drives require a dedicated input isolation transformer. Distribution transformer usually cannot be used as it is not designed for additional harmonic currents, does not have multiple secondary windings to supply the rectifier bridges and most likely does not have the required secondary (LV) voltage level that is strongly linked with the specific VFD topology.
Why VFD transformer rental?
Transformers belong among the most reliable electric equipment. The principle of an electric transformer is known for more than a century. Most of us fully rely on this equipment and don’t even think that it could fail one day…
However, when such failure happens, there is typically a major impact on the business. The reasons of transformer damage might be various:
– design error
– quality issue
– system issue
– insufficient protection
– improper maintenance
– improper storage
– transport damages
In all above cases transformer rental is a way to minimize the consequences.
You might also require a transformer e.g. for testing. Is the voltage level on site different than the voltage level of the test field? Solve it with a rental unit.
Reliability and availability in variable speed drive systems
When talking about reliability many people operate with figures such as mean time between failure (MTBF). This is just one side of the story. Yes, VFD transformers have higher MTBF than the VFD. However, VFD can almost always be repaired on site and in most cases the repair can be done in minutes or hours. In contrast, transformer damage often requires transport to service shop or back to factory. The downtime can take days, weeks or even months.
The probability of a transformer failure is low. However, if it happens, it can have devastating consequences for customer’s business.
What do we offer
Our rental transformers are designed for converter duty applications. The thermal design accounts for harmonics. The insulation is upgraded in order to withstand common mode voltage and increased voltage rise time (dv/dt). Overvoltage protection is provided by in-built surge arresters. The enclosure is suitable for installations both indoors and outdoors (except tropical, highly corrosive or very dusty environment). The transformers utilize dry type technology. The storage locations are mainly in European Union and/or Switzerland. They are in proximity of highways or other main roads for easy logistics and quick transport within Europe. Use in other regions is generally possible if commercially viable and logistically feasible.
References
[1] VFD transformers – Introduction, https://mb-drive-services.com/vfd-transformers-introduction/
[2] VFD transformers – Multi-winding design, https://mb-drive-services.com/vfd_transformer_design/
[3] How to choose a medium voltage VFD: Line side connection, https://mb-drive-services.com/how-to-choose-mv-vfd-line-conn/
[4] Trasfor SA – Dry-type VFD transformers, http://www.trasfor.ch/
Need to rent a VFD transformer? Make an inquiry through the form below.
Please mention basic technical information such as supply voltage and frequency, required transformer pulse number or rectifier input voltage. It will accelerate the evaluation process.
