OPERATIONS & MAINTENANCE
meter and alarm lights on the panel,” says Hodgson.
Continuous monitoring also indicates if the heaters used to maintain thermal temperatures and prevent condensation from forming on the stator coils and cables are working properly. If these heaters fail to operate properly or the circuit breaker is tripped, maintenance personnel may not be aware of it until the motor or generator fails on start- up. Although these heaters are checked regularly, this can leave critical motors and generators unprotected for weeks or even months.
PREVENTING ARC FLASHES According to Hodgson, safety is another major driver behind the decision to install the Meg-Alert devices. Arc flashes are an undesired electric discharge that travels through the air between conductors or from a conductor to a ground. Te flash is immediate and can product temperatures four times that of the surface of the sun. Te intense heat also causes a sudden expansion of air, which results in a blast wave that can throw workers across rooms and knock them off ladders. Arc flash injuries include third degree burns, blindness, hearing loss, nerve damage, and cardiac arrest and even death. Among the potential causes of an arc flash listed by NFPA 70E includes “improper use of test equipment.”
Although de-energising equipment before testing and wearing appropriate
Example of a Meg-Alert panel for generators
personal protective equipment (PPE) is recommended, the best solution is to eliminate the need to access the control cabinets at all to perform insulation resistance tests. “Two hazards we would be concerned about on a platform are
EXTENDING EQUIPMENT LIFE A
ccording to Hodgson, the information generated over time by the devices can also
be used to extend the life of critical motors and generators. Because it provides continuous recorded test readings, the Meg-Alert indicates the approximate remaining life by capturing insulation readings over time. “We send the readings to our data historian, so we can review insulation resistance
20
www.engineerlive.com
electrocution and arc flash,” says Hodgson. “Given that generators on platforms are located within feet of the load, this is even more of a concern because of the high short circuit currents.”
trends,” explains Hodgson. “It helps us understand if a generator consistently has low insulation resistance readings or if it fluctuates up and down and we can attribute it to changing weather conditions. It may also help us determine if the issue is dirty windings or deteriorating insulation.” The information can also be
used to pinpoint the time to ideally schedule the motor or
generator for reconditioning. This feature alone can save an offshore operation thousands of dollars in repair fees because reconditioning is 40-50% less expensive than rewinding. “For critical and significant motors and generators, we want use the data to try and predict failures before they happen and to prolong the life of the equipment as much as possible,” says Hodgson l
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
