G [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]
Galvanic Isolation - A characteristic of an isolation transformer whereby the output is electrically disconnected from the input. Power is coupled from input to output by magnetic fields in a transformer. A galvanically isolated output is considered to be a separately derived source according to the NEC and is required to be grounded. See Isolation Transformer.
Gauss - The CGS unit of measurement for flux density. One Gauss is equal to 1 Maxwell per cm2.
Global UPS (GUPS) - Refers to an UPS being able to operate from either standard US power (120 VAC. 60 Hz) or standard European power (220 VAC, 50 Hz). This covers 95+% of the world.
GND, GRD or G - Ground termination point on equipment. See Ground.
Ground- An electrical ground in a power system is a conductor that is effectively connected to the earth, hence the term "ground". The primary purpose is connect equipment chassis to ground so that it is at the same voltage potential as the ground reduce potential shock hazards to users.
Ground Fault Circuit Interrupter (GFCI) - An electrical device that senses any differential current in connected conductors to determine if there is ground current. If the level exceeds its threshold, the GFCI disconnects the circuit.
Ground Loop - Condition caused when two or more system components share a common electrical ground line. A feedback loop is unintentionally induced, causing unwanted voltage levels.
Guarded switch/CB/etc. - Providing barriers on all sides of the device to help prevent damage or accidental operation of the device. Also allows for locking the device in a particular position for operational or safety reasons.
H [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]
Half Bridge Converter - Converter topology that typically operates as a forward converter but uses a bridge circuit, consisting of two switching transistors, to drive the transformer. Also see Bridge Converter.
Hardwired - Describes any equipment connected to its power source by hardware attached directly to terminal blocks or distribution panels.
Harmonic Distortion - The presence of harmonics that change the AC voltage waveform from a simple sinusoidal to complex waveform. Harmonic distortion can be generated by a load and fed back to the AC utility line, causing power problems to other equipment on the same circuit.
Henry (H)- The unit for inductance.
Hertz (Hz) - Hertz; frequency measurement, 1 cycle per second is equal to 1 Hz.
HiPot - High Potential. Usually refers to a test conducted utilizing a high potential voltage to determine a piece of equipments dielectric withstand capability per safety agency requirements.
Hot-Swappable Batteries - A feature which enables the user to change batteries without powering down the connected load.
Hot-Swappable Power Modules - A feature which enables the user to change power modules without powering down the connected load.
Hz - Hertz; frequency measurement, 1 cycle per second is equal to 1 Hz.
I [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]
IATA- International Air Transportation Association serves the airline industry setting regulations for dangerous goods transported by air.
IEC - International Electro-Technical Commission, a global organization that sets standards for safety of equipment, primarily electrical.
IEEE - Institute of Electrical and Electronic Engineers, a worldwide organization that helps set electrical performance standards.
Immobilized electrolyte - The battery electrolyte is suspended in absorbent materials between the lead plates resulting in no free liquid. This prevents the electrolyte from leaking if the battery case were somehow damaged.
Impedance - Forces which resist (impede) current flow in AC circuits, i.e. resistance, inductive reactance, capacitive reactance.
Inductance - That property of a circuit element which tends to oppose any change in the current flowing through it. The inductance for a given inductor is influenced by the core material, core shape and size, the turns count of the coil, and the shape of the coil. Inductors most often have their inductance values expressed in microHenries (µH) or milliHenries (mH).
Inductor (Choke) - A passive component designed to resist changes in current. Inductors are often referred to as AC Resistors. The ability to resist changes in current and the ability to store energy in its magnetic field account for the bulk of the useful properties of inductors. Current passing through an inductor will produce a magnetic field. A changing magnetic field induces a voltage which opposes the field-producing current. This property of impeding changes in current is known as inductance.
Input Branch Circuit - The Input Circuit from the facility Power Panel circuit breaker to the electronic equipment module.
Input Line Filter - A power filter placed on the input to a circuit or assembly that attenuates noise introduced from the power bus. The filter is designed to reject noise within a frequency band. Typically these filters arc low-pass filters meaning they pass low frequency signals such as the DC power and attenuate higher frequency signal which consist of mainly noise. Band pass or low pass filters are commonly made up of inductor and capacitor combinations.
Input- The switch on the front panel that turns the equipment ON or OFF. When the Input Main switch is set to ON, power is available at the output receptacles of the unit. When set to OFF, no power is available at the output receptacles of the unit.
Input Surge Current - See Inrush Current.
Inrush Current - The momentary peak input current required by electrical equipment when energized. For example, the magnetizing current when energizing a transformer is typically several times the steady state current.
Inrush Current Limiting - Protection circuit that limits the current a converter draws at turn on.
Inverter - An electronic device that converts DC power to AC power (DC/AC). Depending on the inverter design, the output waveform can range from a square wave to a modified sine wave to a pure sine wave.
Internal Bypass - UPS circuitry which provides a redundant power path. If there is an internal UPS fault, the connected load will still be supplied with unconditioned utility power.
Isolation - The separation (often through the use of an isolation transformer) of one section of a system from undesired electrical influences of other sections.
Isolation transformer - A transformer with separate primary and secondary windings and generally a shield between. The main purpose is to allow re-referencing of output connections and to reduce conducted electrical noise. A multiple-winding transformer with physically separate primary and secondary windings. Although the two windings are physically disconnected, the magnetic field in the windings of the primary creates (induces) electrical power in the secondary winding. In this way the electrical power available at the input can be transferred to the output. An isolation transformer does not transfer unwanted noise and transients from the input circuit to the output windings. This attenuation, or reduction in amplitude, could be as high as one million to one.
ITI - Information Technology Industries Council. See CBEMA.
