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Custom Reactors and Inductors

Our custom inductors, reactors and chokes are designed for numerous applications.

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A Reactor is a coil constructed and used predominantly for its inductance or reactance property. For a given current flow, a definite voltage drop exists across the winding. The current flowing through them is all exciting current, so the magnetic circuit is designed to give the required exciting current at the desired voltage drop.

Iron-Core Reactors

The following examples show how Iron Core Reactors are most commonly used:

  • “To increase the reactance of one branch of parallel circuits so the load will divide properly among the branches,
  • “To limit the current of an circuit (ex. arc furnace transformer),
  • "Filter reactors, as a tuned reactor in Harmonic Filter Banks or as a input filter in DC Power Supplies"

“The major effect of adding an iron core to a coil is a great increase in the inductance...” which “often permits the reduction of the coil dimensions, the winding resistance, the reactor weight, or all three.

Air-Core Reactors

“The principle application of air-core reactors is for current-limiting reactors, where the short-circuit current of the system may be many times normal current, with values from ten to twenty times the normal current being typical.”

One type of air-core reactor is a current limiting reactor. Air-insulated (air-core) reactors “consist of a cable wound in a helical form…and supported on a concrete structure with columns of insulating material to support the turns at frequent intervals.” Often, air-core reactors are supported above ground using porcelain insulators.

However, another application may be in "shunt reactors operating at nearly constant voltage to compensate for the leading charging current of a long transmission line."

Technical Capabilities

Standard
Power Ratings 500 VAr up to 250 kVAr
Frequencies
  • 50 Hz
  • 60 Hz
  • 400 Hz up to 20 kHz
No. of Phases
  • 1
  • 3
Voltages
  • Up to 600 Vrms
  • Up to 34..5 kVrms
Oil Types
  • Shell Oil
  • Etc.

Line Reactor

"A line reactor is an inductor wired between a power source and a load. In addition to the current limiting function, the device serves to filter out spikes of current and may also reduce injection of harmonic currents into the power supply. The most common type is designed for three-phase electric power, in which three isolated inductors are each wired in series with one of the three line phases.[8] Line reactors are generally installed in motor driven equipment to limit starting current, and may be used to protect Variable-frequency drives and motors."

The primary application of air-core reactors is for current-limiting reactors, where the short-circuit current of the system may be many times normal current, values of from ten to twenty times normal current being typical.

"Reactors used to limit the current required for the starting of motors may be of either type, depending on the time required by the motor to come up to speed."

From http://en.wikipedia.org/wiki/Current_limiting_reactor#Line_reactor

Current Limiting Reactors

"In electrical engineering, current limiting reactors can reduce short-circuit currents, which result from plant expansions and power source additions, to levels that can be adequately handled by existing distribution equipment. They can also be used in high voltage electric power transmission grids for a similar purpose. In the control of electric motors, current limiting reactors can be used to restrict starting current or as part of a speed control system.

"Where the prospective short circuit current in a distribution or transmission system is calculated to exceed the interrupting rating of the associated switchgear, a current limiting reactor may be selected. The inductive reactance is chosen to be low enough for an acceptable voltage drop during normal operation, but high enough to restrict a short circuit to the rating of the switchgear. The amount of protection that a current limiting reactor offers depends upon the percentage increase in impedance that it provides for the system.

"The main motive of using current limiting reactors is to reduce short-circuit currents so that circuit breakers with lower short circuit breaking capacity can be used. They can also be used to protect other system components from high current levels and to limit the inrush current when starting a large motor."

From http://en.wikipedia.org/wiki/Current_limiting_reactor

Examples

Toroidal Inductor

This 2 mHy custom inductor is toroidally wound. It is used for x, y, and z.

Technical Specifications

Type

Inductor

Inductance

2 mHy ±10%

Frequency

60 Hz

Current

5 Arms

Dimensions

Height = 1.375" Max.

OD = 5.188" Max.

Weight = 3.000" lbs.

Leads

Stranded Leads

Filter Choke for Metallurgy

This 35 mH choke is used to filter out ripples on the line. It is rated at 480 Vrms nominal with a maximum current of 87 ADC.

Technical Specifications

Unit Type

Choke

Inductance

35 mH

Nominal Voltage

480 Vrms

Current

87 ADC Max.

Peak DC Voltage

1,400 V

Frequency

360 Hz

Test Air Core Inductor

This 140 uHy Air Core Inductor was used in a test application at a national laboratory.

Technical Specifications

Inductance

140 uHy

AC Current

300 Arms Continuous

Pancake Reactor

This 140 uHy Air Core Inductor was used in a test application at a national laboratory.

Technical Specifications

Inductance

160 uH

Max. Cont. Current

160 A

Half Cycle 60Hz RMS ASYM

9000

Max Inrush Current

12 kA

Max Surge Voltage

15 kV

Insulation System

180oC