Industry urged to house PFC technology separately to manage risk and boost safety
An authority on causes of industrial switchboard failures says energy saving power factor correction (PFC) technology should be housed separately from switchboards and motor control centres to minimise damage and downtime resulting from any failures.
Consulting forensic electrical and mechanical engineer, Russell F. Lee told delegates at the 2012 New South Wales seminar of the National Electrical Switchboard Manufacturers’ Association (NESMA) that while PFC technology is good technology, “you have to control how it is used and put it in a separate room for prudent risk management”.
“Never put PFC equipment in the same room as the main switchboard or motor control centre, or other apparatus for that matter. Put PFC gear in a separate and fire-isolated room,” Lee warns.
“It is all about prudent whole-of-life management of switchboard systems and application of PFC technologies, because PFC capacitors can and will fail. After five years, you have got to have capacitors checked. The alarm system should shut down the PFC system in the event of high temperatures,” Lee, who has more than 50 years of industry experience and is one of the foremost investigators of the cause of equipment failure, notes.
“With the introduction and now widespread use of metalised polypropylene capacitors, in particular, the incidence of fires because of capacitor failure and ignition must be taken into account during the design, operation and maintenance of switchboards,” he states. According to him, the factors underlying capacitor risk include:
- high operating temperature
- sensitivity to moisture
- failure to self-heal
- sensitivity to harmonics, and
- poor quality film.
“Capacitors don’t often burn, but when they do it can be catastrophic for places such as industries, hospitals and shopping centres if the fire can spread readily because the capacitors are attached to the same chassis as the switchboard.
“It is much better for safety and damage limitation if the capacitor is separate and, therefore, burns in its own room with its own sprinkler, rather than it be allowed to destroy three or four modules of the adjacent board and contaminate maybe three or four others, greatly magnifying the damage and downtime. You have got to be able to cut off the switchboard and limit the damage,” Lee emphasises.
“Designers need to remember that the lowest first cost is not always the right approach when safety and reliability are concerned. The idea that it will become someone else’s problem should give engineers and tradesmen pause for concern. Bear in mind that WH&S laws in all states and territories have implications for designers, manufacturers, installers and end users,” he concludes.