PPPI Engineers design custom base frame for a marine engine, the first time a GE 6L250 would be mated to a base.
Professional Power Products worked with a customer to design a base frame that would support a General Electric 6L250 marine engine. This would be the first time a 6L250, a 900-RPM 1,498 kW (2009 hp) engine, would be coupled to an alternator continuous electricity generation. Taking an engine, alternator, and a flexible coupling (or clutch), PPPI Engineers put together all these elements to a customized package complete with an in-house built electrical control cabinet. The end product is a complete generator set package that will provide continuous power for marine applications.
Before work can begin, many hours of engineering went into designing, analyzing, and simulating various electrical and mechanical systems. Starting with the control systems, Professional Power Products was provided a GE L250 engine controller from which electrical engineers programmed a custom PLC (Programmable Logic Control). PPPI created the PLC architecture to the specifications of the customer in order to interface with various inputs and outputs such as engine components. A customized program was created to control, monitor the engine, and communicate with the existing controllers through the modbus. To give the end user an easy to use interface, engineers programmed the PLC to work with a 15” touch screen monitor. This screen shows items such as engine RPM, engine status, diagnostics screens, and more.
On the Mechanical side, the base frame design was developed through stress and vibration analyses. To satisfy customer design criteria, engineers simulated lifting the structure applying two times gravitational acceleration to double the applied loads. This is done to ensure the safety and integrity of the unit in the most strenuous circumstance. Once stresses were analyzed and found to be satisfactory, a modal analysis was conducted. This was necessary to verify the frame’s frequencies at various vibratory modes exceeded those specified by the engine manufacturer. The results of the modal analysis provided assurance that natural frequencies within the base frame design would not coincide with those of the vibrating equipment, and therefore avoid resonance.
One of the challenges faced by PPPI’s mechanical engineering group was using FEA (Finite Element Analysis) software to simulate a crane lift. The software package, ANSYS, does not have an explicit rigging scenario to simulate the support loads imposed by in lifting; this can only be done through carefully defined boundary conditions. PPPI Engineers devised a technique for applying specific conditions within the software that simulates an actual crane lift. Not only has this helped PPPI satisfy the customer’s design requirements, but also provide PPPI a technique to apply in future projects. This gives PPPI an edge in providing a wider range of engineering services in structural analysis.
In the 2nd quarter of 2010 the completed generator set was shipped to New Orleans, Louisiana, United States and installed as the engine for a dredger. A dredger is a ship that carries out excavation operations in shallow seas or freshwater areas to gather up bottom sediments and disposing of them in a different location. Thanks to the GE 6L250 providing continuous power and PPPI’s expertly designed packaging and control systems, waterways will continue to be navigable and sediments gathered can be used to replenish sand on public beaches to fight coastal erosion.
The completed project was designed and fabricated to meet with many codes and standards, including ISO 3046-1, 8178-1, 8528-1, 8528-2, 8528-3, 8528-5, 8528-9, IEEE 115, NEMA MG1, IEC 60034 1-17, ANSI/ASME section IX, B16.5, B31.3, and D1.1. PPPI’s ISO 9001 certification ensured that proper management techniques were used from start to finish delivering the highest quality possible.