Phase Separated

(Ex ‘d’)

The phase separated terminal box ensures phase to phase faults are eliminated and historically was the preferred terminal box for the majority of 3.3kV and 6.6kV flameproof machines supplied by our former heritage companies (English Electric, AEI and GEC Large Machines Ltd).  Originally developed in the mid 1960’s today, we can offer this box as an identical spares solution for those previously supplied and previously certified.

Technical Description

The outer casing of the phase separated pressure containing terminal box is fabricated from heavy gauge steel securely welded to the solid back and front plates, which have wide machine flanges. On the front of the box are three steel cover plates with flanges and deep spigots, each secured by socket head screws. Cables from the equipment are connected to cone type terminal

assemblies where the plug and socket connectors to the short cable tails are bolted together and protected by synthetic rubber boots. Complete protection against phase to phase faults between the short cable tails within the terminal box enclosure is ensured by close fitting metallic arc shields round each of the cables. The arc shields are bolted solidly to earth via the terminal box casing. They surround the terminals and extend to the bottom plate of the box where the cables pass into the sealing chamber through brass glands with rubber packed sealing rings.

The terminal arrangement is designed to limit the amount of energy which can be released inside the box by ensuring that the arc is kept short and confined to one phase. This enables the casing to be designed to withstand the internal forces and to prevent the passage of flame to the exterior without exceeding practicable limits of size and weight. This type of terminal box is designed for flameproof equipment, where faults could result in explosions or fires. To contain the fault and its resultant products within the terminal box is of the utmost importance.

Spares Support

A full range of spares to support this terminal box assembly are available.

Key Contacts


  • Bu Hasa Extraction Plant

    Replacement Zone 2 to Zone 1, Abu Dhabi

    Learn more

  • Esso Petroleum Company Ltd

    Generator Overhaul, Southampton

    Learn more

  • Kilroot Power Station

    2 pole generator - Major Inspections

    Learn more

  • Rzeszow CHP Power Station

    Generator Major Overhaul, Poland

    Learn more

  • Tongonan Geothermal Power Plant

    Stator re-conditioning and rotor rewind of Generator, Philippines

    Learn more

Connect with us