Let’s explore MV-LV power distribution in Oil and Gas production facilities as well as power distribution and lighting system equipment used in environments with combustible and flammable gases. This paper addresses electrical engineers and introduces the engineering principles of air-insulated MCC and power distribution boards in environments with combustible and flammable gases.

INTRODUCTION

In Oil & Gas industry, power is distributed at MV and LV levels. As an alternative to pump jacks, crude oil is drilled using electric-driven pumps. Electric pumps may consume MV or LV power based on their ratings. Furthermore, certain amounts of chemicals are added to crude oil in order to separate water and other substances after drilling. This system consumes LV power from MCC switchboards. Since air conductivity is a problem in terms of insulation in MV and LV distribution environments, “exproof system” distribution kiosks should be designed to prevent electrical explosions. All rooms that form the distribution kiosk should be heated and cooled with an HVAC system, and insulated from outdoor air that contains combustible and flammable gases. All rooms that form the power distribution kiosk are protected against fire by means of automatic fire detection and suppression systems. Room lighting and external lighting fixtures and switches have “exproof” insulation characteristics against combustible and flammable gases. Power outlets to be used on site for maintenance should also have the same characteristics. System includes a UPS to supply power continuity-sensitive loads of the plant for 8 hours.

Figure 1 shows the power distribution kiosk manufactured as per the standards applicable to Oil & Gas industry. MV cubicle room consists of 4 sections namely MVLV transformer room, LV distribution and MCC switchboards, UPS switchboard room and battery room. In addition, an A/C system and an automatic fire detection and suppression system are available.

GENERAL

For power distribution centers in environments with combustible and flammable substances in oil and gas industry, electrical power is received at MV level and distributed at MV and LV levels. High-power electric motor pumps are supplied by MV power, and dosing and circulation pumps are supplied by LV power. A UPS is available for 8-hour supply to systems that should be powered continuously. Exproof equipment that withstand combustible and flammable gas environments are used for internal and external lighting equipment and power outlets,.

Standards applicable to construction of electricity distribution kiosks in environments with combustible and flammable gases in oil and gas industry

2.2 Construction of kiosks must comply with the following international standards.

The following standards are applicable to selection and installation of electrical equipment

Standards applicable to UPS to be used in the system are as follows;

Standards applicable to transformer to be used in the system;

Standards applicable to manufacturing and assembly of LV distribution and MCC switchboards;

Standards applicable to MV Cubicles;

SECTIONS OF MV & LV DISTRIBUTION KIOSKS

MV Section

In MV/LV distribution kiosks produced for Oil & Gas facilities, gas insulated MV cells are used in order to minimize the MV room dimensions and with the thought that the conductivity of the insulating air will cause problems. Under the MV room, there is a cable compartment at a height to provide the bending radius of the MV cable. The cells in the MV room and the MV busbar are supplied with energy from the energy transmission line located nearby, and the MV/LV transformer in the kiosk – the pump and other systems fed from the MV in the field.

3.2 Transformer Section

It is the section where the MV/LV transformer is located. Depending on the specification, hermetic or dry type transformers are used in the system. Technically speaking, hermetic transformer is preferred because it provides better insulation against harmful gases contained in the environment. The cooling of the transformer is done automatically with the HVAC system by constantly controlling the ambient temperature. MV and LV connections of the transformer are made with special cable heads in accordance with the standards. Cable passages from the cable compartment at the bottom of the room to the transformer are also specially designed.

3.3 LV Section;

LV room houses the LV main distribution and MCC switchboard, HVAC control panel and UPS control and distribution switchboard. Cooling of this section is also provided automatically via HVAC system that continuously monitors the room temperature. LV switchboard is manufactured as type-tested withdrawable in 3D form. Cable entries to all switchboards are provided from the bottom.

3.4 Battery Section;

This is the section that houses batteries that supply UPS system and DC control voltage. Cable connections are also provided from the bottom in this room. Outgoing battery cables are routed to the adjacent UPS switchboard and LV distribution switchboard. Some of the batteries supply the emergency lighting system.

Plant lighting and power outlet systems are designed as “exproof” and must be manufactured so as to prevent electrical sparkling in all the equipment.

4. CONCLUSION:

MV/LV distribution kiosks to be used in Oil & Gas plants must be designed as exproof. Since conductivity of insulation air is higher than the other environments, air-insulated system is not used for the selected MV cubicles. Transformers are hermetic or dry type with insulation systems and the transformer room is completely insulated from the external environment. LV main distribution and MCC switchboards are requested as type-tested withdrawable in 3D form. UPS system should be capable of supplying the plant for 1 hour at the desired rating. HVAC system allows cooling and heating independent from the external environment. Automatic fire detection and suppression systems with CO2 ensure protection against fire.

Compact MV/LV kiosks are manufactured to provide power distribution in Oil & Gas industry under electrically adverse environmental conditions.

5. REFERNCES

İsmail Atilla, Technic Sales Support Manager  Aktif Elektroteknik