The challenge
The existing infrastructure lacked the redundancy and safety features required for modern industrial operations. Positioned offshore, the SL1A Ship Loader faced unique challenges—chief among them, managing up to 1 MW of regenerative energy while connected to the 415Vac Australian electrical grid.
The system also needed to automatically reconfigure its 1 MW regenerative Active Front End (AFE) MCC power circuits into an Active DC-Bus configuration. This would enable dynamic braking when the ship loader switched to its alternative diesel generator power source. And with the inherent risks of such a high-power application, every safety circuit had to meet the rigorous Safety Integrity Level 3 (SIL 3) standards.
The solution
Over an intense 18-week design and build period, the Nidec team engineered a robust, IP44-rated MCC built to “Form 4a” construction standards. The system features:
- A centrally located incomer busbar section will accommodate the main 3-phase, 415 Vac supply, including a raw 3-phase, 415 Vac supply with neutral connection.
- Dedicated sections will also be provided for 24 Vdc and 48 Vdc small power systems, along with overhead busbar chambers for 600 Vdc at 1800 Amps.
- Six segregated MCC shipping sections, including 2 x AFE units and a suite of motoring VFDs.
The entire assembly measured 8600 mm x 800 mm x 2400 mm and weighed in at approximately 8.2 tonnes—including external dynamic braking resistors.
To ensure ease of maintenance, each VFD power unit was mounted on heavy-duty, withdrawable sliders. Operators can access door-mounted controls and remote keypads for real-time diagnostics and operational data per cubicle. The system was powered by Control Techniques’ M702 VFDs, each equipped with dual Safe Torque Off (STO) functionality, ensuring full SIL 3 compliance. All communications were streamlined via Ethernet /IP.
The benefits
The result was a custom-engineered MCC that delivered on every front:
- Enhanced Safety: Dual STO features and SIL 3 compliance significantly reduced electrical hazards.
- Improved Efficiency: Seamless reconfiguration between power sources optimised energy use and performance.
- Ease of Maintenance: Withdrawable sliders and accessible controls minimised downtime.
- Scalability: The modular design allowed for future upgrades with minimal disruption.
Read the full case study:
