Low-voltage air circuit breakers are one component in the power distribution system that will improve reliability and safety on the P-50 floating production, storage, and offloading (FPSO) vessel off Brazil, according to Siemens AG, the manufacturer of the breakers.
Siemens describes its Sentron 3WL communication-capable low-voltage circuit breaker as reliable and modular with a compact design.
P-50 FPSO
The P-50 FPSO (Fig. 1) will handle production from the Albacora East field that was discovered in 1986. The field is in the Campos basin about 120 km from shore. Petrobras expects production to start in third-quarter 2005.
Plans for the field include 31 wells (16 producing and 15 injecting) linked through flexible lines to P-50 for processing before shuttle tankers transport the oil ashore.
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Petrobras expects a production peak of 180,000 bo/d in 2006. Repsol-YPF is a partner in field.
Circuit breakers
The Sentron 3WL circuit breakers on the FPSO protect the 480-v low-voltage circuits that supply power to equipment that requires less than 750 kw (Fig. 2). A COM15 interface with Profibus and glass-fiber cables connects these breakers to the central control room where the breakers are integrated into the process automation system.
The entire low-voltage power distribution system has 45 fields with a total of 98 Sentron 3WL circuit breakers, each fitted with an ETU76B electronic trip unit with graphical display, a measuring function for the recording of measured values, Profibus communication via the COM15 module, and external CubicleBUS modules.
Siemens says that this configuration allows the technical personnel to obtain all important data concerning the mechanical breaker state for the entire system. This includes such information as on, off, ready to switch on, and various measured values such as currents, voltages, and power values.
In addition to these functions, Siemens adds that these breakers also fulfill protective functions such as the switching off the system as soon as a location reaches a defined critical gas concentration. Siemens says these protective parameters are easily and individually set with a switch ES power software during the commissioning of the circuit breakers.
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The process automation system directly controls a CubicleBUS module that is part of the breaker electronics. As with all other breaker parameters, Siemens says this module also can be easily adjusted with the switch ES power software during commissioning of the circuit breaker.
Siemens adds that the software also guarantees the maximum supply reliability of the low-voltage switchgear's load management to both critical, such as the oil production system, and noncritical, such as heating, processes.
If the system's power consumption exceeds a certain limit, the system shuts down the noncritical processes to assure the continuous and sufficient power supply to the critical processes. If the power consumption falls below the limit value, the system switches back on the noncritical processes. For this, the Sentron 3WL circuit breaker provides the measured values for the power flow.
