Introduction To interlocking

With the rapid and unprecedented growth taking place in various fields of engineering, the associated hazards due to human error has also increased many fold, often resulting in loss of life and property.

PSPC are in the fore front of such risk assessment, and providing necessary Safe & Simple, but Robust Trapped Key Interlocking Solution to a host of such problems.

PSPC Trapped Key Interlocks are in service for more than 40 years and are trusted by customers in UK, Germany, UAE, Far East, India and other countries worldwide.


  • PS Interlocks -Simple, Robust and extremely versatile.
  • Any sequence of control / protection is achievable
  • Building Block Approach provides instant solutions.
  • Maximum Protection at Affordable Cost.

How it works?

  • Control Key is released, only when pre-determined condition is established.
  • Key removal prevents reversal of condition.
  • Removed Key used to gain access to the selected hazardous area when hazard no longer exists.
  • Removed Key can activate next step in sequence.
  • No limitation in number of steps and sequences, when used with Modular Key Exchange Units.

How to Plan Requirement

  • Step – 1 : Decide kind of protection needed : Electrical Switch Interlock or Combination to isolate hazard.
  • Step – 2 : Select the Interlock type and accessories that will fit equipment at site.
  • Step – 3 : Determine if intermediate stages of protection are required such as Time Delay etc.
  • Step – 4 : Study carefully examples in the following pages.


The Website does not cover the entire range of products and for special requirements and system Design Help, please get in touch with our Technical Department.