Variable Phase power Plant

Variable phase power plant is a technology developed by BITCOE-IIT Kanpur .This innovation increases the overall long-term running cost efficiency of power plants, in telecom exchanges situated in rural areas , by optimizing the usage of diesel generators and battery. This power plant works with one-two-or-three phase grid inputs depending on availability. The choice of active phase/phases for the operation of the power plant is automatic without any manual intervention. The objective behind this technology was to come up with an AC to DC power plant that works under variable phase conditions. In this way this is better than existing technologies because it produces a regulated DC output without any manual intervention and all the required features of a telecom power plant, eg, isolated output, manual variability ,etc, are intact in the power design .The striking feature of this approach lies in the fact that unregulated and irregular power supply is never a problem for developed countries .

Rural Power Plant

With rapid development, India, has seen a surge in telecommunication and mobile infrastructure all across the landscape. All the telecom exchanges use some form of power supply to provide -48 V DC power to its equipments. Generally, grid is used to provide this power to the exchanges. Battery and Diesel Generators (DGs) are used as back-ups. Due to heavy shortage of grid power, rural India sees long hours of power outages. This necessitates the running the exchanges on DGs or batteries, which increases the operational cost of the exchange.

Telecom exchanges are powered from a three-phase or single-phase AC grid depending on the installed capacity. A telecom power plant takes this grid input and generates DC power for the telecom equipments. Thus, a power plant is essentially an AC to DC rectifier with isolated DC outputs. Currently used power plants work with either single phase or three phase grid inputs depending on the installed capacity of the exchange.

A conventional telecom power plant designed for a three-phase grid input stops working unless all the three phases of the grid are active. This creates operational issues in rural exchanges where grid supply is unreliable and intermittent in nature. In fact, in rural parts of India, a three-phase grid may be partially down with only one or two phases active at a time. Therefore, the use of diesel generators in these exchanges becomes eminent even during partial grid failure, which results in increased carbon footprint and cost of operation.

To solve this problem, a new power plant is designed and commercialized to meet the requirements of rural India. This power plant works with one-two-or-three phase grid inputs depending on availability. The choice of active phase/phases for the operation of the power plant is automatic without any manual intervention. Utmost care is taken to integrate this new design to currently used topologies of power plants so that the integration into existing system can be eased. The development of the power plant was carried out in various stages over the last five years.

In the first stage of the project a proof-of-concept prototype was designed and developed. This prototype exhibited satisfactory operation under universal-phase input conditions. All the operational modes of the power plant were verified in the laboratory.

In the second stage of the project, its commercialization effort was carried out. VMC Systems Ltd., was approached for commercialization of the power plant. With engineering help from IIT Kanpur, VMC systems, developed a commercial prototype by integrating one of their existing designs with IITK design.

In the third stage of the project, the commercial prototype was tested in the field to validate its on-site operation. A field trail of the power plant was conducted at DUDEDA AN-RAX Exchange in SIDDIPET SDCA of MEDAK SSA under Andhra Pradesh Circle. The operation of the power plant was satisfactory under universal-phase input condition up to 50 A loading with good efficiency. Based on this field trail several design up-gradations were recommended by BSNL. In the fourth stage, the design up-gradations were implemented in the prototype.

Power plant Specs:

  • Input Voltage: 90 V-270 VAC (single phase) 320 V-480 V AC (two and three phase)
  • Output Voltage: -44 V to -56 V DC (fully regulated)
  • Output Current: 50 A (two and three phase) 25 A (single phase)
  • Battery Charging: Satisfies all the battery charging specs as per TEC-GR.

Commercialization Specs: As released by VMC Systems Ltd.

Contact details

1. Prof Santanu Mishra-09005211114

2. Prof A. K Chaturvedi-Coordinator,


Dept. of Electrical Engineering ,

IIT Kanpur-0512-2597613,

Developed By: BITCOE (BSNL IIT-Kanpur Centre of Excellence) at IIT-Kanpur