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N - Q

N     [A B C D E F G H I J K L M N O P Q R S T U V W X Y Z]

n  - nano used to express 0.000000001 (10 to the -9th power) times the standard unit, i.e. nA

NEC - National Electrical Code (ANSI/NFPA 70, latest issue), guidelines used by local electrical manufacturers and contractors to insure safer and consistent installations. Developed by the National Fire Protection Association of Quincy, Mass. First published in 1896.

NEMA - National Electrical Manufactures’ Association. Helps set electrical product standards, i.e. electrical plug and outlet configurations.

Network Transient Protector - An in and out RJ11 jack for telephone/modem protection or RJ45 for 10Base-T network cable. It isolates connected equipment such as modem and fax machines from “back door ”power surges.

Neutral - Generally refers to the AC power conductor that is common in polyphase systems (i.e. neutral in a 3-phase WYE) or the conductor that is referenced to ground at some point.

NFPA - National Fire Protection Association. Parent organization for NEC.

NMS - Network Management Device. A system responsible for managing at least part of a network. NMS communicate with agents to help keep track of network statistics and resources. See SNMP Agent.

Noise (audible) - Random, sporadic, or multi-frequency acoustical signals that is generated by the operation of equipment. Since audible noise can be distracting or annoying to the user, designs try to minimize their levels.

Noise (electrical) - Random, sporadic, or multi-frequency electrical signals that become part of a transmission making the signal or information more difficult to identify. Radio Frequency Interference (RFI) and Electromagnetic Interference (EMI) that causes undesirable effects in the circuits of computer systems. Sources of the problem include electric motors, relays, motor control devices, broadcast transmissions, microwave radiation, and distant electrical storms. RFI, EMI and other frequency problems can cause data error, data loss, storage loss, keyboard lockup and system lockup.

Nominal Value - A designated value which has been accepted for the sake of convenience. For instance, nominal voltages are values assigned to circuits so that the voltages of the circuits can be conveniently discussed as 120 Vac nominal units, or 230 Vac nominal units.

Nonlinear Load - A load in which the current does not have a linear relationship to the voltage. In a light bulb, the current is directly proportional to voltage at all times. In a nonlinear load such as switched mode power supplies, the current is not directly proportional to voltage. The peak current of a nonlinear load is greater than a linear (sinusoidal) load.

O      [A B C D E F G H I J K L M N O P Q R S T U V W X Y Z]

OCONUS - Off Continental United States. Refers to an electronic device being able to operate from other than US power, i.e. standard European power (220 vac, 50 Hz).

OEM - Original Equipment Manufacturer.

Oersted - The unit of magnetic field strength (H) in the CGS system. One Oersted equals the magnetomotive force of one Gilbert per centimeter of flux path.

Offline UPS - The unit passes the commercial power to the load normally. When it detects a voltage too low, it turns on its inverter. The delay between utility power loss and inverter startup can be long enough to disrupt the operation of some sensitive loads. Also called a standby UPS. This technology does not provide full time power conditioning. This technology is less reliable overall than on-line at protecting the load from all forms of power disturbances.

Ohm (W) - The electrical unit of measure for resistance.

Ohm Law - The relationship between voltage (pressure), current (electron flow), and resistance. The current in an electrical circuit is directly proportional to the voltage and inversely proportional to the resistance. E=IR, or I=E/R, or R=E/I. Where E=voltage, I=current, and R=resistance.

Oneline Diagram - A schematic of a single phase or polyphase system represented by a single line for all phases..

Online UPS - The technology that fully converts AC power to DC power then back to AC power. This technology provides full power conditioning and protects the load from all forms of power disturbances, including brownouts, blackout, transient surges or sags. In the event of a utility power failure, there is no delay or transfer time to backup power.

Orderly Shutdown - The process of sequentially closing down hardware and/or software processes so that no corruption of data occurs and/or no safety hazards are created.

OSHA - Occupational Safety and Health Act. Federal Safety Regulations applied to the workplace.

Outlet - Any point on a wiring system where current is taken to supply electrical power for a load.

Overcurrent Protection - The circuit or device that protects the equipment from exceeding a specific current level, including short circuit. See Fuse and Circuit Breaker.

Overtemperature Protection - Design feature that protects the silicon die from exceeding its designed operating temperature range. The device will thermally cycle until the abnormal condition is corrected.

Overload - A condition in which the load wants more from the power source (such as a UPS) than the power source has been designed to supply.

Overvoltage Protection - The circuit or device that prevents the output from exceeding a specific voltage level by either clamping output or shutting down the power supply.

P      [A B C D E F G H I J K L M N O P Q R S T U V W X Y Z]

p  - pico used to express 0.000000000001 (10 to the -12th power) times the standard unit, i.e. pF

Parallel Online UPS - Online UPS technology that provides redundant sources of conditioned backup power so that the critical load is protected even in the event of UPS component failure.

Peak Voltage - Also called peak-to-peak voltage, it is a measure of an AC waveform of the highest peak-to-peak voltage present on the waveform.  A proper 120V AC waveform will have a peak voltage of about 170 volts. See RMS.

PDU - Power Distribution Unit. This electrical device is used to control the distribution of power to the individual loads. Control may be as simple as a series of switch or circuit breakers to interlocked logic operating solidstate relays. Available as a stand-alone unit or integrated into the UPS.

Power Factor (PF) - Power Factor, the cosine of the phase angle between the Watts (real power) used relative to the VA (apparent power), (Watts = VA x PF). Can be expressed as a percent or decimal number, i.e. a PF of 0.65 is the same as a PF of 65%.

Power Factor Correction (PFC) - An active or passive input circuit to change the power factor of the input current to a device so that it is closer to a PF of 1.0. Numerous benefits include reduced input line current and lower input harmonics.

Power Conditioner (Line Conditioner) - A unit that provides clean, well regulated power. Input and output voltages may also be converted as well.

Power Management Software - Provides monitoring and shutdown for UPS and connected load.

Push-Pull - Converter topology usually configured as a forward converter, but uses two transistor switches and a center tapped transformer. The transistor switches turn on and off alternately. Also see Boost Regulator, Buck Regulator, Bridge Converter, Flyback Converter and Resonant Converter.

PWA (PCA) - Printed Wiring Assembly (Printed Circuit Assembly), refers to the individual assembled electronic cards used in an electronic product.

PWB (PCB) - Printed Wiring Board (Printed Circuit Board), refers to the bare circuit cards used in PWAs.

Q      [A B C D E F G H I J K L M N O P Q R S T U V W X Y Z]

Q (Q Factor) - A measure of the relative losses in an inductor. It is also known as the quality factor, defined as the ratio of inductive reactance to effective resistance. Q is zero at the SRF of an inductor.