Power Distribution Center Design, 2.4kV Switchgear and MCC Replacement


A Mont Belvieu, Texas, Fractionation Facility was operating a 2.4kV electrical distribution system using 40-year-old outdoor switch gear and motor control centers. The company desired to replace and upgrade this lineup with new-generation switchgear and motor controller technology that meets current design standards and preferred engineering practices.  Replacement 2.4kV equipment design was based on vacuum contactor technology, completely isolated lo- voltage control cabinet, and microprocessor-based protective relays.

ONEOK Hydrocarbons Southwest, LLC selected M S Benbow & Associates (MSB) to provide professional engineering services.  MSB was contracted to write specifications and provide engineering and design expertise to provide a complete IFC Demolition and Installation Drawing Package to replace the outdoor 2.4kV equipment lineup. MSB also served as project engineer and project manager.

The electrical system would be designed for continuous and reliable operation, with an emphasis on operator safety and ease of maintenance.


ONEOK elected to replace the existing 2.4kV switchgear and motor control center and house the equipment in an elevated environmental-controlled Power Distribution Center (PDC) to provide climate control and remove flood hazards.

MSB wrote the specifications for both the new 2.4kV lineup and the PDC.  MSB wrote the Issued For Bid packages, sent it to selected vendors, evaluated their responses, and provided that information to ONEOK for vendor selection.  MSB assisted ONEOK in Purchase Order construction and provided oversight and review services of vendor drawings packages and technical issues.  As the process developed, design changes were made and implemented under the direction of MSB.

As the design team for ONEOK, MSB was also responsible for developing Factory Acceptance Test (FAT) procedures for the 2.4kV equipment and the new PDC.  They participated in the FATs as well as the commissioning and startup of the new system.

MSB developed a complete Demolition & Installation Drawing Package for the project, including:

  • Civil & Structural aspects of the job:
    • Number and types of building support piers
    • Number and types of cable tray bridge support piers
    • Concrete spread-footings for stairs, landings and tray supports
  • Electrical infrastructure:
    • PDC and cable tray grounding plan
    • Cable tray system
    • Power and control cable design and routing plan

Due to an unforeseen land use variance issue late in the design process, the client had to relocate the PDC building site from its planned location, requiring a redesign of the entire civil, structural, and power distribution scheme from the PDC to the loads.  MSB assigned additional resources to the job to meet the compressed project timeline.  This scope change involved extensive coordination between MSB and site contractors to meet deadlines.


The new 2.4kV power distribution system is designed to meet the most current design standards and preferred engineering practices, including vacuum contactors and micro-processor protective relays.  The new elevated PDC building is air-conditioned and well-lit.  It includes a state-of-the-art fire alarm system including an HVAC Shutdown Panel.  The building was designed for future equipment expansion.

ONEOK has replaced old technology (40-year-old outdoor electrical gear) with new state-of-the-art gear.  Reliability, operator safety, and maintenance issues are markedly improved.


SCADA System for Wastewater Treatment Facility


Dock sumps at a petrochemical company process large volumes of liquid oil waste from the dock platform and sanitary waste from operator shelters through skid-mounted pumps and hose manifold stations. Sump pumps then transfer the sump contents to the plant’s waste treatment pumping system, where recovered oil is delivered to tanks while untreated water that meets environmental permit requirements is discharged into the Mississippi River. This transfer operation is controlled by existing float switch pump controls with a manual run option.

The client needed a Wastewater Treatment Supervisory Control and Data Acquisition (SCADA) system upgrade with a more reliable radar signal to meet environmental, safety, manpower and maintenance concerns and comply with Marine Terminal Design Standards.


M S Benbow & Associates (MSB) was contracted to upgrade current controls to a SCADA and telemetry for the pump stations, which involved monitoring the sump alarms, levels and pump status at seven remote sewage pump stations, integrating all of the stations on the same SCADA, communications and telemetry platform.

MSB was the engineering firm responsible for drafting & design, engineering, specification and testing of the SCADA upgrade.

The project to install equipment and instrumentation necessary to meet the standards required elevated dock sump vents and visual and audible high-level alarms. Per the standards, the sumps must be a closed system with a vent to the atmosphere. The vents should be pressure/vacuum regulated and discharge a minimum of 9.8 feet (3 m) above platforms and 50 feet (15 m) from any equipment; and sump tanks should be designed with high-level alarms displayed in a central manned location.

Work required was to:

  • Install mechanical piping as necessary to move vent point to 9.8 feet above sump top and 50 feet from any nearby equipment.
  • Piping modifications at the sumps would require flushing and inerting the vessels so structural supports could be installed to support additional vertical and horizontal sections of vent piping to meet elevation and distance requirements.
  • Install pressure-vacuum vent relief valve on vent piping.
  • Install SCADA system components (wireless radios, programmable logic controller and enclosures with battery backup) and local alarm beacon and siren at each dock location.  Continuous level and high level alarms will be displayed at each sump location as well as a centralized manned operator location.
  • Install process connection on sump for new radar-level instruments.
  • The SCADA/alarm panel enclosure components were DC powered sourced from a battery bank located within the enclosure. The battery bank consisted of two redundant 24 VDC power supplies as a charging source fed from the docks’ 120VAC power panels. Each new alarm panel would receive power supply from two sources, the docks’ local power panel and an emergency battery bank reserve.


MSB developed a test procedure for the client to field function test the wireless SCADA system as well as participate in a factory acceptance test prior to converting to the new system.

The system continuously monitors inputs, transmits the sensor readings at regular intervals, and alerts operators when an alarm is detected. The system can also be monitored remotely 24/7.

The project established more reliable and accurate level-measuring instruments. Furthermore, because of the new wireless SCADA infrastructure at these dock locations, installation costs were minimal.

The system will reduce the operation’s probability of overflowing the sumps into the Mississippi River, thereby reducing the client’s environmental impact. Increased reliability also can potentially prevent downtime, expensive fines or lost revenues.


Industrial Electrical System Optimization through Analysis


A large Oil & Gas storage and transportation company with a major storage location in Texas and various stations along its pipeline needed assistance analyzing its electric utility system. The company’s liquefied petroleum gas (LPG) storage complex in Mont Belvieu, Texas, one of the nation’s largest, delivers LPG to customers as far away as New York. The facility was experiencing excessive voltage drops under normal conditions and various rural locations along the distribution pipeline also were experiencing electrical transmission issues.

The company needed a qualified engineering company to perform analyses and make recommendations for improving the electrical distribution system at the Mont Belvieu storage property as well as several rural locations along the pipeline system.


Understanding how electric generation, transmission, and delivery systems interact and operate is paramount to guaranteeing reliable sources of electricity. Bringing a combination of detailed theoretical modeling and real-word experience, M S Benbow & Associates (MSB) was enlisted to conduct power system engineering studies and provide system capacity and optimization analyses for the oil and gas pipeline electrical system.

MSB evaluated existing studies performed by local power utility companies and developed a model of the storage facility’s electrical distribution system using SKM Power*Tools DAPPER and TMS software modules. Engineers also performed a modified load flow and motor starting analysis and a system fault current analysis.

MSB provided detailed flow analysis reports for several operating scenarios, a transient motor starting analysis for different starting methods and operating loads, recommendations to improve and upgrade the performance of the electrical system, and cost estimates for different solutions for achieving varying degrees of reliability.


The client applied the studies to its upgrade projects and was able to determine the most cost-effective solutions for optimizing the electrical distribution system that met its financial and reliability goals.

The client realized savings at the storage facility by improving voltage levels without having to increase distribution voltage or purchase and install electrical equipment such as auto-transformers and larger conductors. In one location along the pipeline route, the local utility recommended a seven-figure investment to install new lines while the client was able to present a six-figure alternative recommended in the MSB-provided analysis. The line work was later scheduled as part of the utility’s routine maintenance at no cost to the client, resulting in substantial financial savings.


Startup, Commissioning and Operation of a Grass Roots 230 kV-13.8 kV Substation


In order to meet consumer power demand and improve reliability of their facility, management at a major refinery enlisted site engineers to design, start up and commission a new 230 kV-13.8 kV 40 MVA spot network substation. The genesis of the new substation was rooted in the realization that both the existing substations reflected the design philosophy of the period and had shown signs of overloading during their service life. The project sought to provide capacity to meet a 10- to 20-year load forecast. The new substation was to utilize the following key features:

  • Utilize multi-tiered relay protection with overlapping zones of backup protection.
  • Incorporate microprocessor-based relays because of greater accuracy and repeatability, multiple protective functions located in one box, and the availability of communications, self-monitoring and event reporting.
  • Utilize remote manual breaker controls located beyond the arc flash exposure zone within the substation building. These controls were to be used to open, close, rack in, and rack out the 13.8kV circuit breakers in the substation building.
  • Install a main-tie-tie-main configuration that allowed complete power supply isolation for maintenance access. The tie was designed to operate in the closed position to improve the substation reliability and limit single points of failure.
  • Implement a redundant relay design providing equipment isolation that is limited to a single zone of protection during a potential relay failure.
  • Utilize a 230kV half ring bus configuration to improve the reliability of the electrical transmission system.

The design, construction and testing of the substation had to be rigorous and methodical. The client required seamless implementation of the startup, as a functional failure in a main electrical substation could result in equipment damages far exceeding the initial cost outlay of the substation. Delays would result in a significant financial and environmental impact.


M S Benbow  & Associates (MSB) was engaged to ensure that the startup, commissioning and operation of the substation was executed with as little interruption as possible. The management directive was to complete a “flawless” startup to avoid a costly functional failure of the substation, which could easily result in damage that would exceed the initial costs of the substation.

Planning, implementation and adaptability are critical to a successful project. For this reason, a procedural-based, layered approach to substation startup and commissioning was developed. MSB was part of a team consisting of specialists, site engineers, utility engineers, consultants and a project manager. The start-up team was comprised largely of members not involved in the original planning and design, thus providing an opportunity for a fresh set of eyes to verify that the system would perform as desired prior to proceeding with factory testing and startup.

MSB developed detailed test procedures and checklists that were compiled from manufacturer drawings, refinery test procedures, industry test procedures and team members’ individual experience. These procedures and checklists detailed the processes for factory acceptance tests and site checkout and commissioning, which included tests for:

  • Circulating current – to verify directional relay settings and CT polarities
  • Secondary current injection – to test relay operation
  • Primary current injection – to simulate faults and verify CT connections
  • Primary voltage injection – to simulate faults and verity PT connections
  • Bolted ground fault – connecting a conductor between phase and ground on a resistance grounded system to test the ground system protective relaying
  • Load simulations – using test sets to simulate actual load conditions
  • Functional simulations – to verify the multi-tiered relay protection logic would operate as intended


MSB helped the client startup, commission, and operate a grass roots substation that met the core goals of safety, reliability, and increased load capacity and equipment protection.

The startup was implemented in phases and load was successfully added to the substation without power outage to the unit, minimizing facility exposure.

As planned, the startup was flawlessly implemented, due in large part to M S Benbow’s commitment to methodical and thorough review, testing and documentation processes. After the substation was checked out and commissioned, MSB developed detailed operating procedures for each piece of equipment in the substation.

With the enhanced capacity and a thoroughly tested new substation with accurate drawings and procedures, the company subsequently transferred additional units to the new substation, reducing load on existing antiquated substations and improving reliability.