From SI48-10 to modern DC power systems – the development of telecommunications power supply technology
11/08/2026
Author: Justyna Rojek
One exhibit, over 30 years of development
At the exhibition dedicated to the history of technology at the Silesian University of Technology in Gliwice, you can see a device of particular significance to MERAWEX – the SI48-10 rectifier, one of the first models developed by the company for telecommunications power supply systems.
Today, its design differs significantly from that of modern DC power systems. Energy conversion technologies, control methods, diagnostic capabilities, and communication methods have all evolved. The basic function, however, has remained the same: to provide stable power to loads and maintain their operation in the event of a mains power failure.
Comparing the SI48-10 with modern SI48 systems makes it possible to trace how the technology used in telecommunications power supply systems has evolved over more than 30 years.
SI48-10 – a design for 48 V DC systems
The SI48-10 was a rectifier powered from a single-phase 220 V AC mains supply.
The device performed the basic functions required in a standby power supply system:
- conversion of AC voltage to DC voltage,
- output voltage stabilization,
- battery charging,
- operation with the battery during a mains power failure,
- protection of the battery against excessive discharge,
- indication of operating and fault conditions.
The nominal output current was 10 A, and the output voltage was 55.2 V DC. This value was related to the charging requirements of the lead-acid batteries used at the time.
An important design feature was its modular construction. The SI48-10 consisted of a control panel and two replaceable power modules. This design increased system reliability and allowed servicing to be performed without shutting down the entire system.
This was particularly important in telecommunications systems, where an interruption in the power supply to active equipment could result in an interruption of services.
Operation with a battery
In telecommunications systems, the power supply system must operate with the battery and ensure proper charging conditions.
The SI48-10 used circuits responsible, among other things, for voltage stabilization and control of the charging process.
One of the solutions was temperature compensation of the charging voltage. The voltage was adjusted according to the battery temperature, which helped reduce the risk of battery overcharging or undercharging.
The system was also equipped with an RGR circuit, i.e. a deep-discharge disconnect device. If the battery voltage dropped excessively, the battery was disconnected from the load. This protected the batteries against the effects of excessive discharge.
In designs developed in the 1990s, implementing these functions required appropriate measurement, control, and switching circuits.
What has changed in successive generations?
Looking at the SI48-10 and modern MERAWEX DC power systems, several areas can be identified where technological changes are particularly evident:
- energy conversion technology,
- miniaturization,
- digital control,
- battery management,
- diagnostics and communication.
1. From conventional designs to switch-mode power supplies
In older designs, magnetic components and other low-frequency components accounted for a significant share of the device’s weight and dimensions. The development of switch-mode technology made it possible to use significantly higher switching frequencies in energy conversion circuits.
As a result, it became possible to:
- reduce the size and weight of devices,
- increase power density,
- reduce energy losses,
- achieve higher efficiency,
- implement more advanced control methods.
Modern rectifier modules used in SI48 DC power systems achieve efficiency exceeding 90%.
2. From analog control to digital control
In the SI48-10, control and protection functions were implemented using conventional analog circuits.
Modern DC power systems use microprocessor-based controllers that allow multiple parameters to be measured simultaneously and more advanced control algorithms to be implemented.
The controller can monitor, among other things:
- output voltage and current,
- input parameters,
- the status of individual modules,
- temperature,
- battery voltage,
- alarm conditions,
- rectifier operating parameters.
This change affected not only the way voltage is regulated. It also made it possible to integrate control with diagnostics and communication.
3. From local indication to remote monitoring
In older systems, information about the device status was provided primarily locally, using indicators and alarm contacts.
Modern power supply systems can communicate with higher-level devices via digital interfaces such as RS485 or Ethernet. Depending on the configuration, the device parameters can also be accessed over a network and integrated with monitoring systems.
Information about the system status can be transmitted to a monitoring center, while historical data can be used for diagnostics.
4. Advances in battery management
The battery remains one of the most important components of a standby power supply system. However, the capabilities for monitoring it have evolved.
In older solutions, monitoring was primarily based on voltage control and appropriate management of the charging process. Protection against deep discharge was also used.
Modern systems can analyze a much larger number of parameters related to battery condition. Depending on the configuration, it is possible to monitor, among other things, voltage, current, temperature, and parameters that can be used to assess battery condition.
This represents a shift in the approach to diagnostics – from reacting to an alarm after it occurs to detecting irregularities at an earlier stage.
35 years of development of the core power system function
The basic task of the SI48-10 and the modern SI48 DC power system remains the same: to provide stable DC power to the loads and maintain their operation in the event of a failure of the primary power source.
What has changed is the way this task is accomplished.
We have moved from designs using analog control circuits, conventional power components, and local status indication to compact power systems with high-efficiency switch-mode modules, digital control, advanced diagnostics, and network communication.
The SI48-10 unit displayed at the Silesian University of Technology represents one of the milestones from which the development of the MERAWEX family of telecommunications power systems began. Comparing it with modern solutions shows not only how the device design has changed, but above all how the technologies used to perform the same basic function – ensuring continuity of power supply – have evolved over the years.
Would you like to discuss your project requirements?
Do you need support in selecting a solution, preparing technical documentation, contract manufacturing, or other services? Describe your needs in the form. We will contact you to discuss possible areas of cooperation and answer your technical questions.
-
1
After receiving your enquiry, we will contact you by phone or email.
-
2
During the call, we will discuss your requirements and propose suitable solutions.
-
3
If necessary, we will arrange additional technical consultations.
-
4
We approach each case individually, so you can be sure that our response will be tailored to your requirements.