Current Limiting Reactor, 250 Continuous Amps, 480 VAC L-L,

60000 Available Amps, 5000 Fault Limit Amps, P/N KK-36

A current-limiting reactor is used when the prospective short-circuit current in a distribution or transmission system is calculated to exceed the interrupting rating of the associated switchgear. 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 for 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.

The customer application is shown below:

 

Current Limiting Reactor, Three-Phase

The inductance calculations are shown below:

  • L-L = 480 VAC
  • V L-N = 277 VAC
  • Assumed available Fault Current = 60000 Amps
  • Assumed Fault Current = 5000 Amps
  • Z system (based on Available Current) = 277 / 60000 = 0.00462 Ohms
  • Z system (based on Designed Fault Current) = 277 / 5000 = 0. 0554 Ohms
  • Z needed = Square Root of (0.0554² – 0.00462²) = 0.0552 Ohms
  • Inductance = 0.0552 / (2 x 3.142 x 60) = 147 uH
  • Reactance Voltage Drop = 0.0552 Ohms x 250 Amps = 13.8 VAC
  • Percentage Voltage drop = 13.8 / 277 = 5.0 %

Specifications:

A. CLR, 250 Amps continuous, 3 PH, 60 Hz, 480 V, P/N KK-36
B. Assumed available fault current: 60000 Amps
C. Assumed current limit: 5000 Amps
D. Copper windings
E. Approvals: none
F. System shipping weight: 700 lbs.
G. Three inductors in one indoor enclosure (68″H x 65″W x 44″D)
H. Calculated Inductance Value:147 uH, 250 Amps continuous
I. Percentage Voltage Drop: 5.0 %

 

The detail of one Air Core Inductor, KK-29-1 is shown below. Three KK-29-1 are required for one CLR KK-29.

 

 

 KK-36-1. Three are required per system

 

Specifications:

  • Air Core Inductor, P/N KK-36-1
  • L (1, 2) = 147 uH
  • Continuous Current: 250 Amps
  • Frequency: 60 Hz
  • Copper windings
  • Approvals: None
  • Copper bus bars are 1″ x 1/4″ thick
  • One CLR consists of three separate air core inductors in one indoor enclosure

The System consists of three inductors in one indoor enclosure. The layout is shown below:

 

 

The photo of the enclosure (68″H x 65″W x 44″D) is shown below:

Three Inductors in one enclosure

All our CLR’s are custom-built to order. To discuss your specific application, please call our phone number at (714) 624-4740, or send us an email at quote@lcmagnetics.com.