Seacor Glory achieves ABS compliance and more
Operating a fleet of offshore marine support vessels, Seacor Marine’s main operation involves offshore oil and gas exploration and production. One of their ships, Seacor Glory is a dieselelectric offshore cargo ship equipped with DC (direct current) motors and is presently operating in the Gulf of Mexico.
Seacor Glory was refurbished between 2014 and 2015, making the ship susceptible to the latest American Bureau of Shipping (ABS) electrical and mechanical directives. According to these regulations, Seacor Glory’s vessel type and grid type necessitates an 8% voltage THD (total harmonic distortion) limit and 5% individual voltage harmonic limit. Due to the the severe voltage notching associated with the SCR (silicon controlled rectifier) drives and DC motors aboard the vessel, uncompensated distortion was high – in excess of 20% voltage THD!
Furthermore, due to the unusually low ceiling of Seacor Glory’s switchgear room, the switchgear cubicles are short. The cramped space also meant that a compact solution was optimal.
Shipped to Texas and implemented into the switchgear in early 2015, the solution was then shipped to the vessel itself while in port in Namibia for installation in spring 2015. The solution was then finally commissioned during the summer of 2015.
Each side of the ship’s 600 voltage bus bar was fitted with a set of three ADF PPM300 units. The PPM300 is the inverter module in an ADF P300. In this case, Seacor Marine purchased components (not complete systems), which were then custom-installed in the vessel. Thanks to the systems being shipped as components, Electric Power Design was able to fully integrate a tailor-made solution into the existing switchgear lineup.
Additionally, each set of three units (one starboard set and one portside set) is controlled by a SCC2 control computer.
Voltage distortion has been reduced significantly* and continuous monitoring of the vessel’s power quality has been achieved. Seacor Glory is thus compliant with ABS regulations—with the added benefit of enabling the vessel operators to better monitor the ship’s performance. Prior to 2015 regulations, vessels were not required to monitor their power quality, leaving distortions and other problems unchecked. With the new mandate and tools such as the ADF PPM300 and the SCC2 computer, ship operators have enhanced control of their vessel, thereby avoiding power quality problems and the down time associated with them.
A common problem that many vessel operators face is finding a solution that works with their ship’s unique architecture – and Seacor Glory was no different. But with the flexibility that comes with ADF, Electric Power Design was able to deliver a solution in the form of components (rather than complete units), saving Seacor Glory from complicated and expensive redesign.
*With ADF , voltage distortion was reduced from 24% voltage THD to less than 7% voltage THD, with significant improvements noted for all individual voltage harmonic distortions as well. Furthermore, to achieve continuous supervision of the vessel’s voltage distortion, the SCC2 control computer provides a solution where the power quality data can be read out from a PLC (programmable logic controller) over Modbus.