Harmonics are a harmful condition that can occur in electrical environments. Ideally, electricity is delivered at a set and sustained frequency—typically 60Hz in the US. Realistically, disturbances and distortions occur that add frequencies to the electricity. Harmonics are propagated both downstream to equipment and upstream into the power grid. The effect on the grid depends on the severity of the harmonic distortion and the size of the total energy pool.
One way to visualize the relative impact of harmonics is to think of ripples in a body of water. The effect of the ripples depends on both the size of the body of water and the stone that makes the ripples. For example, a pebble in the ocean has little discernable effect. A boulder dropped in a small pond creates a big disturbance.
Non-linear devices are a significant source of harmonics. These devices change the frequency of the power used, changing the waveform. A short list of non-linear devices includes computers, printers, fluorescent lights, power supplies and variable frequency drives. Use of these devices continues to rise, while the available power grid is at best slowing increasing.
Harmonics are a growing issue in the oilfield. Some of the problems they cause include:
- Inefficient energy. Harmonics reduce voltage. Operators get less voltage for the same power cost.
- Hot motors. High current resulting from harmonics can overheat motors. This heat can significantly damage equipment or even cause burnout.
- Breaker trips. Spikes or faults caused by harmonics can trip breakers. This takes pumps and potentially other equipment offline and defers production.
- Interference. Harmonics can cause interference both downstream and upstream into the power grid. Neighbors may complain about interference in their electrical systems including televisions, lamps and computers.
Fortunately there are a number of ways to mitigate harmonics, improving energy efficiency, reducing maintenance costs and improving goodwill with the utility and neighbors.
For a more detailed look at harmonics, read our white paper “Cancel Harmonics Using an Active Front End.”