SAN JOSE, Calif.† December 10, 2002† The compelling need to protect modern communication networks in data centers, base stations, and colocation sites from power disturbances is driving the demand for power quality (PQ) equipment and services in North America.
CODE CITATIONS Article 225 Feeders Article 230 Services Article 250 Grounding Article 408 Switchboards and Panelboards Article 445 Generators Article 680 Swimming Pools, Fountains and Similar Installation Systems NFPA 20 1999 Standard for the Installation of Stationary Pumps for Fire Protection Grou
* For referenced figures, please refer to ELECTRICAL CONTRACTOR magazine. If the data recorded appears to violate the laws of physics, apply the test of reasonableness to the data before attempting to fix something that isn't real.
CODE CITATIONS Article 100 Definitions Article 210 Branch Circuits Article 230 Services Article 250 Grounding Article 312 Cabinets, Cutout Boxes and Meter Socket Enclosures Article 445 Generators Article 518 Places of Assembly Disconnect for multiwire branch circuit Q: There was a requirement in the
A load or circuit with significant loads that have rectified inputs will most likely have a true power factor (W/VA) that is less than displacement power factor (cosine of angle between voltage and current).
210.52(C)(5) Receptacle Outlet Location Provisions stipulating the placement of receptacle outlets are covered in 210.52 through 210.63. Requirements for placing receptacles in dwelling units are located in 210.52(A) through (H).
A single-phase, rectified input, switching power supply will have a sharp reduction in current at the beginning of a sag, followed by an increase in current to a value greater than the original current levels, until the sag has ended or the equipment trips off line.
210.52(C)(3) Peninsular Counter Spaces Article 210 covers branch circuits except those that supply only motor loads. Motor load requirements are covered in Article 430. Receptacle placement provisions for dwelling units are stipulated in 210.52(A) through (H).
CODE CITATIONS Article 90 Introduction Article 110 Requirements for Electrical Installations Article 250 Grounding Article 404 Switches Article 430 Motors, Motor Circuits and Controllers Article 440 Air Conditioning and Refrigerating Equipment Routing grounding electrode conductor Q: We have to inst
CODE CITATIONS Article 110 Requirements for Electrical Installations Article 230 Services Article 240 Overcurrent Protection Article 310 Conductors for General Wiring Article 430 Motors, Motor Circuits, and Controllers Article 450 Transformers and Transformer Vaults Article 695 Fire Pumps Warning si
A voltage sag originates at the startup of a motor. if the voltage drops quickly and steadily increases, you have sag. Some signatures of power quality (PQ) phenomena are difficult to discern from the megabytes of data that PQ monitors can produce in a relatively short time.
(Please refer to ELECTRICAL CONTRACTOR magazine for referenced figures). On a single-phase circuit, the origin of a voltage sag is usually downstream if the neutral-to-ground voltage significantly increased during the sag.
For the past three years, this column has covered a different power quality-related topic each month. Now that most of the major areas have been covered, it seems as though it is time to use a different approach.