Retrofit – the cost-efficient solution for system modernisation





DNP3 and IEC 61850


Replacement of obsolete equipment and protocol migration


Retrofit consists of the replacement of technologically obsolete equipment in a system, taking advantage of reusable components and materials, such as electrical wiring and circuitry and cabinets. This is more economical than a complete replacement of the system.

The equipment to be replaced may be fully functional, but with old electronics and off-market components, with discontinued support from the manufacturer and more costly repairs.

In Retrofits, obsolete equipment such as RTUs, serial busses, proprietary converters or relays are replaced in less than a few minutes thanks to the use of adapted and prepared connection cards to link the existing circuits with the new devices to be integrated into the system.

Retrofit projects additionally aim to migrate from the communication technologies of the 80s and 90s based on serial and proprietary protocols to modern standards based on TCP/IP and open communication protocols. Network protocols not based on TCP/IP are often referred to as legacy protocols.

Serial protocols are characterised by the sequential sending of bits one at a time through the communication channel, and the most commonly used in substations are RS-232, RS-422 and RS-485. They have the added limitation of lacking the ability to time stamp the messages sent.

On the other hand, the TCP/IP model of Internet protocols, allows both the use of open (non-proprietary) communication protocols and the implementation of precision timing protocols, such as PTP. The main open communication protocols in substation automation are:

  • DNP3: Distributed Network Protocol version 3. It is a set of Communications Protocols (layers 2, 4 and 7) for automation and telecontrol with serial and TCP-IP capabilities widely used in substation automation and communication with control centres.
  • IEC 61850: Standard for substation automation using MMS, GOOSE and SV (Sampled Values) digital communication protocols over Ethernet networks with PRP/HSR redundancy topologies. It is the standard that is gaining a lot of traction.

For more information, please contact 61850@im3.cl


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