OPERATIONS & MAINTENANCE
HANDS-OFF
Constant monitoring of critical motors and generators on offshore oil platforms while offline prevents failures on start-up, reduces production interruptions, saves on rewinding repairs and increases personnel safety
APPROACH F
or decades, offshore oil and gas personnel have performed insulation resistance tests with handheld megohmmeters to
prevent motor and generator failures that lead to costly unplanned shutdowns, production interruptions and rewinding repairs. However, these tests only provide a snapshot of motor or generator health. In a matter of only a few days, windings and cables that are exposed to salt air, moisture, chemicals, contaminants or vibration can become compromised and fail at start-up. Portable megohmmeters also require electrical technicians to manually disconnect the equipment cables and connect the test leads on potentially energised or damaged equipment to perform the manual testing. Tese tests
expose technicians to potential arc flashes when they access the cabinet. In the USA, non-fatal arc flash incidents occur approximately five to 10 times per day, with fatalities at the rate of approximately one per day. With so much at risk, offshore platform operators are recognising the value of continuous megohm testing and monitoring of insulation resistance that initiates the moment the motor or generator is off and continues until it is re-started again.
Armed with this information, maintenance personnel can take corrective actions ahead of time to avoid a failure that would interrupt production. By doing so, they can save oil and gas producers hundreds of thousands of dollars in lost production and repair
fees for expensive rewinding as well. Furthermore, permanently installed automatic testing devices allow for ‘hands-off’ monitoring without having to access cabinets – keeping technicians out of harm’s way.
MOTOR PROTECTION ON OFFSHORE PLATFORMS Offshore platforms rely heavily on their main generators and a variety of motors, though the number and type vary depending on the size of the platform and rate of production. On a deepwater or ultra-deepwater platform, several hundred motors may be installed, with five-10 categorised as critical or significant (high- cost motors that are not easily replaced). On exceptionally large platforms, up to 30 critical motors might be involved.
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