Electrical Noise

Electrical noise is any unwanted electrical signal traveling on electrical wires.

Common causes: switching loads on and off, motors, transmitters and arc welders.

Common symptoms: severe cases of electrical noise can cause lock-up of sensitive electronic equipment, computer malfunctions, misoperation of communication equipment, radio and phone line interference.

Common solutions: specialized filters.

Harmonics

Harmonics are defined as distortions of the normal voltage or current waveforms.

Common causes: 'non-linear loads' such as adjustable speed drives, rectifiers, computers/office equipment and fluorescent lighting. These devices use electricity (current) differently from motors or incandescent lights, distorting the normal voltage and current patterns.

Common symptoms: include transformers and motors overheating, electrical wiring overloading/overheating (especially neutrals in three phase systems).

Common solutions: specialized filters applied at the source equipment.

Outages

Outages An outage is a complete loss of voltage for more than a few (five) minutes. If the interruption is less than a few minutes it is called a momentary.

Common causes: lightning strikes, damage to utility lines during inclement weather, downed power lines due to vehicle accidents or distribution equipment failures.

Common solutions: back-up generators.

Power Quality

Power Quality is the concept of powering and grounding sensitive (electronic) equipment in a manner that is suitable for the reliable operation of that equipment. Power Quality relates to the equipment's immunity levels when faced with power disturbances such as: sags, outages, surges, swells, electrical noise and harmonics.

Reliability

Reliability is a measure of the power availability, calculated as a system average. The national average is around 99.98%, which, while impressive, may not be satisfactory for sensitive equipment or critical operations. Users need to install specific equipment to obtain the desired up time. Utilities track their reliability performance with a variety of indices focused on system wide outage duration and frequency. The reliability statistics (as defined by IEEE standards) refer to outages beyond five minutes.

Sags

Sags are voltage level drops, below the nominal range, for a short time (lasting from a fraction of a second to a few seconds).

Common causes: start-ups of large motor loads (such as chillers and air conditioning units) and normal utility operations in face of abnormal system conditions (such as storms, wildlife intrusions onto utility equipment, tree limbs touching wires and vehicular accidents with utility poles).

Common symptoms: flickering lights and equipment shutdown or reset.

Common solutions: UPS - Uninterruptible Power Supplies also know as battery back-ups. In some special cases, certain types of voltage regulators may be used.

Surges

Surges, also known as spikes or impulses, are extremely fast voltage changes above the normal range, lasting no longer than a few milliseconds (a millisecond is a one thousandth of a second).

Common causes: lightning strikes, equipment start-ups/ shutdowns and capacitor switching operations. Lightning strikes are the most damaging voltage transient in the BGE service territory.

Common symptoms: range from electronics lock-ups and resets to hardware damage, usually visible as charred or burned components and a 'burned' smell.

Common solutions: quality surge suppressors. However, there is no effective surge protection against a direct lightning strike

Swells

A voltage swell is an increase in voltage above the normal level for a short duration of time.

Common causes: large loads being shut down inside the facility or temporary lack of adequate voltage regulation on utility feeder.

Common symptoms: in severe cases, equipment may drop-off or be damaged.

Common solutions: voltage regulators and UPS - Uninterruptible Power Supplies.