Medium Voltage Trap Reactor – Inner Secrets Revealed!

Docta Reacta:  Welcome to the inner sanctum of PMI Institute!  Today, we reveal one of the major secrets that have made the Power Magnetics, Inc. floating core medium voltage trap reactors (MVTR) an industry standard.  Read on, dear PMI Institute student!

Using (3) 1Ø ‘Floating Core’ Reactors vs (1) 3Ø ‘Grounded Core’ Reactor

On the 1Ø :

Single Phase Medium Voltage Trap Reactor

Single Phase Medium Voltage Trap Reactor


In a “Floating Core’ Medium Voltage Trap Reactor, the center point of the reactor winding (usually (2) coil) is tied to the core, which itself is mounted on insulators (or ‘floated’ off ground).

This has the advantage that the vast majority of the line-to-line (L-L) voltage appears across the insulators, so that the steady static operating voltage stress within the reactor is minimal. Because of this, the PMI ‘Floating Core’ medium voltage trap reactor construction is pretty much ‘bullet proof’.  Of course, it goes well beyond this in the design and manufacturing, but that is as far as we can go publicly!

On the 3Ø :

Three (3) Phase Medium Voltage Trap Reactor

Three (3) Phase Medium Voltage Trap Reactor




The alternative is to make the reactor as one 3Ø unit, not a grounded core. With this construction, the full L-L voltage appears across the coil insulation to ground, as well as phase to phase.

The two most popular voltage ratings are 5kv class, 60kv BIL and 15kv Class, 95kv BIL. Our Grounded Core Medium Voltage Trap Reactors have been impulse tested up to 95kv BIL. We also have a very reliable field service record of over 10 yrs. with our current construction.

Summary: (3) 1Ø Floating Core Reactors vs (1) 3Ø Grounded Core Reactor

  • Reactor costs are approximately the same for either solution
  • The (3) 1Ø reactors take up a lot more room and are more time-consuming to install
  • PMI’s 3Ø Grounded Core Reactors are very reliable. Nonetheless, PMI ‘Floating Core’ reactor is still the gold standard in the industry.
  • If the 3Ø Grounded Core Reactor would be too large, it still may have to be made of (3) 1Ø Reactors.
  • 1Ø Reactor cost of a spare is much less.

So there you have it, dear students, for your edification, illumination and reflection on my elucidation of the inner secrets of Power Magnetics, Inc.’ gold-standard-of-the-industry medium voltage trap reactors!  (Our marketing nerd made me write that last line 🙂 ).  I am just the tech guru.

Until next week!



Related Posts