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Harmonic Suppression Reactor

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  • P15851 - Permanent HSR-42
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Harmonic Suppression Reactor - HSR

Neutral grounded power line capacitor banks provide a convenient path for power line harmonics, commonly the 9th harmonic (540 Hz in a 60 Hz power system), to couple into communication lines. The result is noise.

The Harmonic Suppression Reactor (HSR) effectively shifts the capacitor bank's resonant frequency and reduces its noise interfering effects. Telephone companies have reported power influence (noise-to-ground) reductions greater than 20 dBrnc after installing HSR's at capacitor bank trouble spots.

In fact, it is possible for HSR's to provide greater noise reduction than disconnecting the bank entirely, or "floating" the ground/neutral connection (which can result in a power company safety hazard).


  • Entire telecommunication route is noisy
  • Noise starts and stops on cable route at specific times
  • One 50/60 Hz harmonic is substantially higher than either adjacent harmonic
  • Power line capacitor banks failing prematurely, or adversely affecting power line operation
  • Excessive or unexplained fused cutouts or blown circuit breaker operation on a distribution power line

HSR-FT3 Field Test Reactor

The FT-3 test reactor is used for temporary, monitored installation in capacitor bank neutrals to "detune" or determine the optimum location and inductance for permanent HSR installations. The FT-3 contains four six-position make-before-break tap switches, which provide a total of 36 values of inductance.

Because of the wide inductance range, the number of winding taps, and the necessity of keeping the FT-3 as small and light as possible, it is designed with smaller gauge winding conductors than a permanent HSR. The FT-3 should never be used in unattended field installations.

Each FT-3 test reactor is furnished with a calibration chart that lists the inductance of each tap setting for that particular test reactor. The HSR-FT3 is available for rent by the week.

Part No. Model No. Additional Description Size (H"x W"x D")
P15851 HSR-42 Permanent 3 - 42 mHy

18.12 x 21.75 x 17.50
(46 x 55 x 44 cm)

P15293 HSR FT-3 Test Set 3-85 mHy

20 x 20 x 9
(51 x 51 x 23 cm)


Mounting Bracket (for dual

P31031 HSR-100 Permanent 100 mHy

Tank - 14 dia. x 25
Overall - 20.5 dia.x 31


HSR Features

  • HSR-42 and HSR-100 are enclosed in a metal, epoxy filled case with 5 kV class distribution bushings for field connection. There is a grounding lug on the case.
  • The HSR is furnished with an industry standard distribution transformer bracket for double bolt mounting to a utility pole. A special pole-mounting bracket is available for twin HSR installations, which are quite common. (Part No. 22744T7)
  • A 3 kV class MOV distribution surge arrester is included with each HSR and mounted on top of HSR case.
  • A recessed, removable cover on the front provides access to the terminals on permanent HSR-42.

"Swamp Out Major Harmonics"

100 mHy HSR

The 100 mHy HSR (P31031) has sufficient inductance to swamp out major offending harmonics, while at the same time insuring that if properly used it will not put the circuit into resonance at 180 Hz.

Electrical Specifications

Inductor Inductance Range DC Resistance at 20 degrees Celsius

Continuous Current Thermal Rating

FT-1 Inductor 3 to 20 mHy (each tap approx. 0.3 mHy) 0.144

21 amps

60 Hz RMS

FT-2 Inductor 13 to 85 mHy (each tap approx. 1.5 mHy) 0.512

11 amps

60 Hz RMS

HSR- FT3 Overall

3 to 85 mHy Contains FT1 and FT2 inductors within one fiberglass case.  
HSR-42 3.0 mHy to 42.0 mHy 0.014 to 0.04

50 amps

60 Hz RMS

HSR-100 100 mHy +/- 5% .025

50 amps

60 Hz RMS