The Main Distribution Frame is the basic interface which provides an interconnection or a connection field between the subscriber lines and the exchange equipment. The MDF not only provides for connections between the subscriber and the exchange equipment, it also houses the protective equipment to protect the subscriber line and the expensive exchange equipment from over-currents and high voltage surges.

The MDF consists of a specially designed steel frame consisting of a number of individual parts assembled together to make a rigid structure. The individual parts are so designed that there is total interchangeability and ease of erection at site even by semi-skilled staff. The steel items are coated with a special hard-wearing material to protect them from atmospheric action. The wiring is made extremely simple and does not necessitate removal of the insulation, wrapping and soldering. The design of the connection elements and the unique tool provided to make the connections ensures a positive connection of the wire on the contact. The connecting elements and the protective equipment are modular in construction and totally interchangeable enabling easy installation and maintenance. Alteration of wiring to suit the day-to-day requirements is extremely simple. Presently the MDF are available in four varieties:

* 128/256 MDF for small rural automatic exchange
* 512 port MDF for SBM exchange
* 1000 lines per vertical MDF
* 1600 lines per vertical (High density MDF)

Check Feature: Totally Dust-proof. No soldering & no wire wrapping at site. Transparent and toughened fire proof shutters. Modular in construction. Both wall and floor mounting. No pre-wiring is required.