23 May Retrofit – the cost-effective solution for system modernization
The Retrofit consists of the replacement of technologically obsolete equipment in a system, taking advantage of reusable components and materials, such as wiring and electrical circuitry and cabinets. This action is cheaper than the complete replacement of the system.
The equipment to be replaced can be fully functional, but with old electronics and integrated outside the market, with discontinuity of manufacturer support and more expensive repairs.
In Retrofits, obsolete equipment such as RTUs, serial connection buses, proprietary converters or relays are replaced in less than minutes thanks to the use of adapted connection cards prepared to link existing circuits with the new devices to be integrated into the system.
Retrofit projects also seek to migrate from the communication technologies of the 1980s and 1990s based on proprietary serial protocols to modern standards based on TCP/IP and open communication protocols. Network protocols not based on TCP/IP are often called legacy protocols.
Serial protocols are characterized by the sequential sending of bits one by one through the communication channel, and the most used in substations are RS-232, RS-422 and RS-485. They have the added limitation that can’t time-stamp messages.
The TCP/IP model of Internet protocols, on the other hand, allow both the use of open (non-proprietary) communication protocols and the implementation of precision time 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 remote control with serial and TCP-IP capabilities, widely used in the automation of substations and communication with control centers.
· IEC 61850: Standard for the automation of substations using digital communication protocols MMS, GOOSE and SV (Sampled Values) on Ethernet networks with PRP/HSR redundancy topologies. It is the standard that is gaining ground with a lot of traction.
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