TransGrid owns 137 backup alarm systems that provide a combined alarm service as a secondary service to SCADA SMART alarm [ed: something missing here, TransGrid??]. It is a microprocessor-based system capable of transmitting and receiving 10 simultaneous alarms. SMART alarms currently account for the entire population of backup alarm systems in the network. This system has an expected life of 20 years.and
SMART Alarm transceivers have been installed as the backup alarm system. They provide a 10-function alarm service in both transmit and receive directions and have been designed to interface with all of TransGrid’s communications channels. SMART alarms currently account for the entire population of backup alarm systems in the network.
This system has an expected life of 20 years and at present there are no performance issues.
source: TransGrid Network Management Plan 2011_web.pdf pages 55 and 68
The "SMART Alarm" was a project I completed back in 1997 while working at TransGrid. I don't recall how it came to be called the SMART Alarm...I think it may have been because it was microprocessor controlled, which was a huge leap forward from the op-amp filtered, 5-pulse-rate alarm system designed in 1982 that it was replacing.
The "designed to interface with all of TransGrid’s communications channels" means that originally, it was designed to work with 50 baud E&M signalling channels, over either a power-line carrier or microwave radio link. Yes. Fifty baud. You can almost watch the bits go by.
I still have a copy of the manual I wrote for it, which covered the basic theory of operation, installation and configuration.
From the Hardware Overview section of said manual:
The SMART alarm system is a 10 input, 10 output microprocessor controlled status transmitter and receiver built on a singe 220 millimetre length Eurocard board, designed to operate from a positive earth, 50 volt DC supply. As the system is fully microprocessor controlled, the flexibility of the system is limited only by the hardware constraints of the board, and what can be programmed in software.
I have fond memories of that project; developing the design, the PCB layout with Protel on Windows for Workgroups 3.11, writing the software for the 8051 in assembly language. Good times. PCB auto-routers have improved a lot since then, though. If I recall correctly, it was painfully slow.
So, a device installed in over 130 sites, with an expected lifespan of 20 years. And (to quote from the report) "no performance issues" as of 2011?
I must have done something right!