The Bailey INFI 90 is one of the most durable distributed control systems ever built. Plants that commissioned it in 1990 still run it, and many run it well. But ABB no longer makes the modules. The IMASI analog inputs, the IMMFP multifunction processors, the IEPAS power supplies and the IMDSO digital outputs are all out of production. ABB’s answer is a migration path to Symphony Plus. If your plant has a funded migration, that is fine. Everyone else now runs a system that lives almost entirely in the secondary market. You have to manage it that way.
We have repaired more than 350 INFI 90 modules since 2009. That includes the IMASI13 and IMASI23 more than 80 times between them, and the IPSYS01 power system more than 60 times. Our customers are co-generation plants, utilities and industrial sites. Here is what we have learned about keeping the system healthy.
The modules that fail, and why
INFI 90 failures are not evenly spread. Power supplies and power-system modules fail most. They run hot, and their electrolytic capacitors have been in service for three decades. Analog input and output modules fail next. The fault is usually in the front-end signal conditioning or on a single channel. Plants report “channel 6 bad” or “reads offset” rather than a dead card. Processor modules fail least. They are also the hardest to replace, because a replacement must carry the right firmware revision and the right loop configuration.
That pattern tells you where to put your spares budget. A plant with two tested spare IEPAS02 power supplies and two spare IMASI cards on the shelf, under warranty, has covered most of its exposure. A plant with one untested spare of everything has covered less than it thinks.
Repair versus replace
For most INFI 90 modules, component-level repair is the right answer. The boards are large and through-hole. They are well documented. The failed components are almost always passive or power devices still in production. A repaired module keeps the exact revision your system expects. A repair typically costs 40 to 60 percent of the secondary-market price for the same module. It carries a warranty. A used module carries whatever history it came with. Repair is also the only option that preserves your module count. Every working unit in the world was built before 1998.
Replacement makes sense in two cases. The first is a module that failed in a way that damaged the board itself. The second is a module you do not hold a spare for and cannot wait three weeks to repair. In both cases, buy from a source that tests and warranties what it sells. Then send the failed unit for repair anyway, so it becomes your spare.
The two things a spares shelf should never lack
The first is a test record. A spare that has sat in a cabinet for eight years is not a known-good spare. It is a hypothesis. Electrolytic capacitors age on the shelf as well as in service. The single most effective thing an INFI 90 plant can do is test its spares on a schedule. Do it during a planned outage, once or twice a year, and put each spare under a fresh warranty. A spare that fails in the cabinet costs you a repair. A spare that fails in the rack during an outage costs you the outage.
The second is a register. Record which modules sit in which cabinets, their revisions, how many spares you hold of each, when you last tested each one, and which have failed before. Most plants keep a version of this in a spreadsheet that one person maintains. When that person retires, the plant discovers how much of its sustainment lived in their head. Move the register out of the spreadsheet and into a document the plant owns.
What “another ten years” actually costs
You can sustain an INFI 90 deliberately. That means tested spares, a repair relationship with a defined turnaround, an annual inspection cycle, and a register. For a mid-sized plant, it costs a small fraction of a Symphony Plus migration each year. You can stop at any time once the migration is funded. Or you can sustain it accidentally, one emergency at a time. That costs more. It is also the reason migrations get approved in a hurry after a bad outage. Plants that make the migration decision on their own schedule got the sustainment right first.
Would you like a no-cost review of your INFI 90 spares? Send us the list. We will tell you what you hold, what is repairable, and what still carries a warranty. You will have a one-page report within a week.
Powergenics repairs ABB Bailey INFI 90 and Procontrol modules, GE Speedtronic Mark IV/V/VI/VIe cards, Westinghouse WDPF cards and Siemens Teleperm modules for power plants across North America. Three-year warranty on every repair. No fix, no fee. Richmond, Virginia. 800-861-9773.