Instrument Selector Switches

Rotary Knife Switches


Rotary knife switches are modular & compact in design and are very versatile for switching a.c. as well as d.c. resistive & inductive loads. These Switches are used as Mode selector switch and as instrument selector i.e. Ammeter selector & voltmeter selector switches. They offer a benefit to select and measure currents & voltages between phase and between phase and neutral.

Features & Specification

  • Selection of current & voltages between phases or between phase and neutral.
  • Superior insulating material ensures electrical stability.
  • Self cleaning of contacts is done during the operation.
  • Modular design to achieve any number of poles with minimum components.


Rotary knife switches are generally suitable for 45°, 60°, 90° angle of rotational operation. The operating knob is followed by a steel shaft which passes through indexing mechanism and series of moving contact blades made of phosphor bronze material. The two blades of phosphor bronze shove over fixed terminal, having inbuilt properties of good wear resistance ensures positive contacting and durability of contact. The terminals are housed in disc shaped housing and the terminations are open to free air.

Cam type rotary switches can be used as instrument selector switches to achieve high electrical duarbility and endurance.