Iron Core Reactors for Harmonic Filter Bank Applications – Part 2

Docta Reacta: Here is more enlightenment and edification on the trade-offs between three phase reactors and single phase reactors, harmonic filter reactors if you will, when used in harmonic filter banks.  Iron core reactors can be designed as either single phase or three phase.  There are trade-offs for each reactor type summarized below.   It may appear that there is a bias towards single phase reactors, and certainly these is more than sufficient cause.  One can appreciate the trade-off in durability by examining the construction of the two different types.


single-phase-trap-reactor             three-phase-grounded-core-trap-reactor


While it is certainly possible to make three phase reactors as durable from a BIL ratings standpoint, doing so in any size even approaching something comparable to three single phase reactors in not practical.  Thus  the reason most harmonic filter bank manufacturers normally use single phase harmonic reactors.  The focus is on long term reliability of the units as they tend to be deployed in industrial applications where down time due to reactor failure is not an option, either from the cost or time perspective.  The capacitors in a capacitor bank have a limited life and are expected to be replaced, but the reactors should not ever need to be replaced over the useful life of the filter bank.

Even the seldom used but recommended practice of maintaining a spare within the filter bank enclosure is more practical with single phase reactors.


When examining the trade-offs carefully between the two approaches if there is any potential for accommodating the slightly larger size of three single phase harmonic reactors, or trap reactors, the choice is nearly always to use single phase trap reactors.

Until next session, this is Docta Reacta signing off!

Now what happened to that errant Dr. Transformer? I think I saw him raiding the candy bars again………  There he is, talking to a furnace transformer…..??   He needs to get out more often…….


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