Extending Equipment Life

Nov. 2, 2005
Four ways a power monitoring system can help

It’s no mystery that maintaining your equipment will maximize its useful life - change the oil in your car regularly and you might be able to hand it down to your teenager; ignore it and it might not outlive the bank note. Here are three more rules for extending the life of your equipment:

  • Apply equipment as it is meant to be applied (e.g. don’t use a DC motor when an induction motor is the better choice).
  • Operate equipment as it is meant to be operated (in a suitable environment, per the nameplate).
  • Minimize external effects (e.g. variations of electrical parameters) that violate the first two rules.

To achieve the third rule, proper information is required - the kind of information that is provided by a capable power monitoring system. The following are four ways a power monitoring system can help extend the life of your equipment.

  • Monitor and detect sags, swells, and transients. Power quality disturbances, such as voltage sags/swells and transients, can disrupt sensitive processes and damage equipment. A power monitoring system can identify and log power quality disturbances. Voltage sags and swells can be plotted on the ITIC or SEMI curves, helping to identify when corrective action is necessary, and providing a means to determine if equipment is being operated within specified tolerances. Advanced power monitoring systems can even provide “disturbance direction detection,” helping you pinpoint the source of disturbances.
  • Monitor and detect under-voltage and over-voltage conditions. Under-voltage and over-voltage conditions can cause excessive heating in motors and transformers. This can drastically shorten their useful life. A power management system can monitor for under- and over-voltages and generate alarms, allowing you to take corrective actions to maximize the life of your equipment (for example, derating motors to compensate or notifying the utility of the condition when its source is outside the building).
  • Monitor and detect voltage unbalance. Three-phase motors operated on unbalanced voltages will overheat; many overload relays can’t sense the overheating. A power management system can detect and warn of unbalanced conditions so that corrective action can be taken. (See The ABCs of Voltage Unbalance.)
  • Monitor and detect harmonic distortion. Excessive harmonics can cause problems in building power systems, including current overload on neutral conductors, blown capacitor fuses, and increased heating and stresses in capacitor banks and transformers, thereby shortening equipment life. A power monitoring system can measure the harmonics in a power system and provide information on total harmonic distortion (THD). A power monitoring system can also provide information on individual harmonics in the system and on harmonic power flows, both of which are useful for determining the locations and types of harmonic-producing loads. By understanding the type and magnitude of harmonics in the system, steps can be taken to minimize them (for example, by purchasing low-distortion electronic ballasts).

Jim Giordano is a certified energy manager and a staff product specialist in Schneider Electric’s power management division (www.us.schneider-electric.com or www.powerlogic.com), and is located in La Vergne, TN.

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