Variable Frequency Drive in Railway Applications

25th June 2024

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Train manufacturers around the world face unique power conversion challenges. A recent application in the UAE required conversion from 400VAC 3-phase 50Hz to 230VAC single-phase at 60Hz at 3000VA for passenger electronics. This article looks at the TDS-3300 and TDX-3300, cutting-edge variable frequency drives that offer precise control over variable frequencies in railway systems.

Background and Client Needs

Variable Frequency Drive project in UAE

Converting 400V AC 50Hz to 230V 60Hz is no small feat, often presenting several engineering challenges. One of the primary issues lies in the voltage transformation itself. Reducing 400V to 230V requires robust electronics capable of handling high input voltages while delivering a stable, lower output. Ensuring that the inverter can efficiently manage the power without significant losses or overheating is crucial.

Another significant challenge is the frequency conversion from 50Hz to 60Hz. This frequency shift affects the performance of electrical devices.

To address both these issues involves rectifying the AC input to DC and then inverting it back to AC at the desired frequency. This process must be precise to avoid introducing harmonics and other distortions that could damage sensitive equipment. Implementing effective filtering and shielding techniques is essential to mitigate these effects and ensure a clean power output.

Lastly, the physical size and cost of the conversion equipment can be a constraint. Engineers must design compact and cost-effective solutions without compromising on performance or reliability. Balancing these factors requires a deep understanding of power electronics, thermal management, and regulatory requirements, making the task of converting 400V AC 50Hz to 230V 60Hz a complex but essential engineering challenge.

Furthermore, ensuring compliance with safety standards and regulations is a critical aspect. Different regions have specific electrical codes and safety standards that must be adhered to, which can complicate the design and implementation of the conversion equipment. 

Outcomes and Benefits

The TDS-3300 Variable Frequency Drive from Premium PSU proved to be the ideal choice for converting 50Hz to 60Hz on, ensuring that passenger electronics operated seamlessly. This robust, compact solution is specifically designed to address the challenges of varying power frequencies encountered in rail transport. The ability to work with outputs from 5 to 75 Hz off the shelf made it an ideal solution, with short lead-times and minimal engineering set up.

The TDS-3300’s compact design and high efficiency make it an ideal fit for the limited space available in train carriages. Its rugged construction ensures durability and reliability under the demanding conditions of the railway environment, including vibrations and temperature variations.

Additionally, the Variable Frequency Drive’s advanced features, such as programmable parameters and fault protection, offer ease of integration and maintenance. This results in reduced downtime and lower operational costs for train operators. 

TDS-3300 Series

variable frequency drive

Expansion into New Projects

Following on from the TDS-3300, Premium PSU recently introduced the TDX-3300, a ground breaking 3-phase to 3-phase Variable Frequency Drive that redefines power conversion efficiency and reliability. Designed to cater to the demanding needs of industrial applications, the TDX-3300 excels in providing precise control over motor speeds and torque, enhancing performance across various sectors.

TDX-3300 Series

3-phase to 3-phase

The TDS and TDX series are devices that convert either AC to AC or DC to AC. They keep the output voltage stable, even if the input voltage varies. These units can handle sudden increases in load according to a specific characteristic curve and protect against short circuits by turning off the output and restarting after a while. If the short circuit persists after several restarts, the output shuts down and needs an input voltage reset.  Outputs can also be turned on or off remotely using an opto-isolated signal. There are also alarms for output and input failures, which activate if there is a problem like a short circuit, overload, internal issues, or if the input voltage is outside the specified range. 

Variable Frequency Drive

The TDX-3300 boasts advanced features such as programmable parameters, robust fault protection, and a user-friendly interface, making it easy to integrate into existing systems. Its compact design ensures it fits seamlessly into limited spaces, while its rugged construction guarantees durability under harsh industrial conditions.

Technical Superiority

The TDS-3300 and TDX-3300 showcase superior technical capabilities, providing precise control of variable frequencies ( 5 to 75Hz) and output voltage adjustment from 20 to 100%. This technical edge not only met the clients’ immediate needs but also position them for future technological requirements.


Relec Electronics has represented Premium PSU in the UK for the last decade and the TDS-3300 and TDX-3300 are the latest additions to a powerful portfolio of railway compliant power products.  Both Premium PSU and Relec Electronics are renowned for providing reliable, efficient solutions that result in high client satisfaction, increased production, and expansion into new projects.

Why settle for standard when you can unlock so much more?

Enhance your railway equipment with our expert solutions. Let’s start a conversation today! 

GET IN TOUCH TODAY – 01929 555700

At Relec Electronics, we are committed to empowering your applications with the right power conversion solutions. Leveraging our extensive knowledge and experience, we guide you through the selection process, ensuring that you have all the information you need to make the best choice for your specific needs.

In the ever-evolving world of power electronics, having a trusted partner like Relec Electronics by your side ensures that you are equipped with the right tools and knowledge to navigate the complexities of power conversion, driving your applications to new heights of performance and reliability. 

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