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LB-5 Load Box

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Load Box

The LB-5 Load Box helps to prevent the damaging effects of ferroresonance found on lightly or unloaded 3-phase power systems.  This situation typically occurs on medium voltage distribution transformers and power cables during single phase switching.  As the electric power industry moves towards more efficient transformer design, this condition is becoming more common.  If such conditions exist, overvoltage can lead to the breakdown of insulation resulting in damage to the transformer, lightning arresters and other equipment.  When using the LB-5 to connect and apply a resistive load on the transformer secondaries, damage to distribution equipment due to ferroresonance can be prevented.

Load Box model LB-5-1 includes an additional switch to disconnect the center of this Y connected load from the ground lead. This is required for corner grounded delta transformer connections.


Load Box Features

  • Helps prevent ferroresonance during single phase switching
  • Portable, one person design
  • Dual voltage, auto voltage selection
  • Powered by transformer secondaries 120/277VAC
  • 5,000 watt per phase loading
  • Resistive load up to 3 phases
  • 40A fused disconnect switch
  • Blown fuse indicator lamp
  • Auto-ranging voltage input - no switching required

HD Electric Company is committed to ongoing review and improvement of its product lines, and thus reserves the right to modify product design and specifications without notice.