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Test Interfaces for Power Systems



The Long Test Switch (LTS) is designed to safely disconnect IED's from the system and provide test access. Usable as a retrofit to FT switches in the same cutout size, or in any other application calling for test switches, the LTS provides many benefits.

Contact opening and safe make-before-break CT-shorting are achieved via integrated disconnect pins. Banana jacks provide test access. Separate test plugs are not needed, but available as an option. This translates into cost savings, prevention of errors, and very flexible usage.

Key Features

  • Finger safe design increases safety
  • Long back end of LTS test switch makes cabling easier, bringing the terminals closer to those of relays and other IED's
  • Integrated CT circuit shorting bridges in current disconnect pins, between 2 or 4 ganged contact modules
  • Disconnect pins are keyed to the corresponding contact type to eliminate human error
  • Two rows of customizable labels on the test switch front, plus labeling on pins
  • Very low internal resistance helps reduce heat in cabinets and panels
  • 10-pole size fits FT switch cutouts

Principle of Operation

LTS in Normal Operation
The LTS test block contains 8, 10, 12, 14, 16, 18 or 20 modular units (or poles) each allocated to a current, voltage, signal or trip circuit. Each circuit is connected through the block via two silver-plated copper contacts, pressed securely together by two pressure springs to create a highly conductive electrical connection. In this situation, a electrical connection is established between the device side (B) and the system side (A).
LTS in Test Position
When the disconnect pins is in the "test" position, a banana jack is accessible on the device side of the test block, allowing the connection of a test set and the associated signal injection. The banana jack on the system side is optional, but it is always accessible, if present.