M - Mega, used to express 1,000,000 (10 to the +6th power) times the standard unit, i.e. MVA.

µ - micro, used to express 0.000001 (10 to the -6th power) times the standard unit, i.e. µF

m - milli, used to express 0.001 (10 to the -3rd power) times the standard unit, i.e. mA

Magnetic Synthesizer - A three-phase ferroresonant based system with zigzag output windings to allow the Ferro to handle unbalanced loads.

Maintenance free battery - This means that during the normal operation of the battery, there will not be a need to add water or electrolyte.

Make-Before-Break - Operational sequence of a switch or relay where the new connection is made prior to disconnecting the existing connection.

Manual Bypass Switch - (MBS) A manually operated transfer switch used to bypass the major electronics in the UPS, so the UPS can be serviced without power interruption.

MIB - Management Information Base. The database of information (or variables) related to a particular network device or collection of network devices. The MIB is a collection of stored guidelines that allow a NMS to know what information can be provided by the various devices on the network which might be polled for status information. The popularity of SNMP has resulted in the development of standards for storing data critical to network operation, the Management Information Base (MIB). MIB-II, the latest generation of network management MIBs, stores data on TCP/IP traffic, routing, configuration and errors. MIB-II has improved support for multi-protocol devices and allows the NMS to control SNMP operation

MOV - A Metal Oxide Varistor. A MOV is a voltage sensitive breakdown device which is commonly used to limit overvoltage conditions (electrical surges) on power and data lines. When the applied voltage exceeds the breakdown point, the resistance of the MOV decreases from a very high level (thousands of ohms) to a very low level (a few ohms). The actual resistance of the device is a function of the rate of applied voltage and current. A varistor is a very rugged voltage clamping device capable of absorbing very large currents without damage.

MSDS - Material Safety Data Sheet. A data sheet containing the chemical makeup of a product and whether it has any hazardous properties. For example, the batteries used in these products has an MSDS.

MTBF - Mean Time Between Failure. The measurement of the reliability of equipment expressed in the average operational hours before a service interrupting failure. Based upon either actual operating data or calculated data per MIL-HDBK 217.

MTTR - Mean Time To Repair. The time to repair a piece of equipment on the average.

Multinational Input - Refers to ETI products being able to operate from standard voltages of 100 VAC, 120 VAC, 200 VAC, 220 VAC or 240 VAC having either a 50 or 60 Hz frequency. This covers 99+% of the world.

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

NDIA - National Defense Industrial Association.

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.

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 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.