MCC switcboard for the Offshore Fixed Platform in the Caspian Sea

The project included manufacturing of an MCC with withdrawable feeder drawers to power equipment on an oil platform.

Okken is the foundation for bold design decisions

We proposed to implement the project using Okken withdrawable drawers.

The use of Okken as a system made it possible to solve several problems at once:

  • Okken low-voltage switchgear has a modular design, which makes it easy to change or upgrade in case of a technological process development.
  • The switchboard was designed with free slots to add new functions or extra motor feeders, even at the last minute
  • The Okken LV switchboards incorporate the best safety and protection systems, preventing on-load operation to guarantee safety operation and maintenance
    Live parts are protected by screens guaranteeing an IP20 degree of protection.

Partitioning form 4b / 4a

Form 4b is provided for all feeder cells:

Partitioning of functional units from each other and from busbars is ensured, the terminals of external conductors are located in different compartments from the functional block, but in individual, separate protected spaces or compartments.


For soft starter drawers, partition form 4a is ensured:

Separation of busbars from the functional units and separation of all functional units from one another, terminals for external conductors are located in the same compartment as the assotiated functional unit

Tin Plated Copper Bus

The oil rig platform is located in the open sea, which dictates the conditions for the application of anti-corrosion treatment of the switchboard busbars. The specification required the use of a tin-plated copper busbars. Tin coating of busbars was carried out by galvanic method with the coating thickness of at least 30 microns

Silver plated contact connections

To reduce the electrical connection resistance, the power busbars connection points were silver-plated.

46 withdrawable distribution and motor feeders

Withdrawable drawers allow to upgrade switchboard with power on, without interruption of service, and completely safely


Drawers have three positions:

  • connected,
  • test,
  • disconnected.


Switchboard configurations and settings are made on the front face

4 soft starters for 75kW motors

For 75 kW motors Altistart 48 soft starters were used with a bypass contactor, which makes it possible to reduce the heat generation in the cabinet from the soft starters constantly operating under load.


Soft starters non-standard installation, made it possible to reduce the overall dimensions of the switchboard, but required additional thermal calculations and selection of a ventilation system.

Tesys T intelligent control and protection relays for motors up to 75kW

Tesys T protection relays made it possible to implement motor protection functions, parameter measurement, remote monitoring with full integration of each drawer into control system.

75kW motors are protected by intelligent protection control device Sepam M40

  • wide possibilities for protection settings
    event recording with timestamps, synchronization via SNTP
  • network diagnostics and oscillogram recording in fault modes
  • access to settings and remote monitoring via Ethernet  communication protocols: Modbus TCP / IP, IEC 61850
  • “ring” topology connection to the network

Using 3D modeling tools

A detailed 3D design of the switchboard allowed us to reveal and avoid mistakes, which could only be identified at the assembly stage.


Thus, only proven solutions are delivered to the assembly.

Network data collection and transmission to the monitoring system

Each panel of the MCC switchboard is equipped with a Modicon M241 industrial controller with Modbus and Ethernet interfaces, integrated inputs, and outputs. The controller collects information about drawers’ status,  data from PM710 measuring devices, and Tesys T protection relays.


The collected data is transmitted via Ethernet to the Modicon M251 controller, which acts as the central hub of the MCC monitoring system.


For connecting to the platform control system an Ethernet switch with ring topology is installed in the MCC switchboard. Modicon M251 controller, PM870 metering devices, and Sepam M40 protection relays are connected to the switch.


It makes possible complete monitoring of  all main switchboard components, and prompt remote configuration of Sepam M40 protection relays (if there is an appropriate access level)