NonStop S-Series Planning and Configuration Guide (G06.26+)

Glossary
HP NonStop S-Series Planning and Configuration Guide—523303-017
Glossary-30
electromagnetic interference (EMI)
electromagnetic interference (EMI). Forms of conducted or radiated interference that
might appear in a facility as either normal or common-mode signals. The frequency of
the interference can range from the kilohertz to gigahertz range. However, the most
troublesome interference signals are usually found in the kilohertz to low megahertz
range. At present, the terms electromagnetic interference and radio frequency
interference (RFI) are usually used interchangeably.
electrostatically shielded transformer. A transformer that has a metallic shield placed
between the primary and secondary windings. This shield diverts high-frequency
signals to ground.
electrostatic discharge (ESD) protection kit. A kit containing an antistatic mat and a
wriststrap with a cable and grounding clip. A service provider or customer wears the
wriststrap while performing maintenance procedures inside an enclosure. The
wriststrap and cable contain grounding wires. When the grounding clip is attached to a
metal object, such as the enclosure, the person wearing the wriststrap is grounded.
Any static electricity incurred during the procedure is discharged safely to the ground
instead of to electrical components within the enclosure.
ELF. See Executable and Linkable Format (ELF).
emergency power off (EPO). Describes equipment used to automatically disconnect all
electrical power to connected equipment if an emergency occurs. A computer room’s
main EPO system shuts off all room equipment (except for lighting and fire-sensor
equipment) if a fire occurs. An equipment zone EPO shuts off power to all connected
computer equipment if the EPO switch is activated.
emergency power-off (EPO) connector. A two-pin connector on the service side of an HP
NonStop™ S-series system enclosure that allows an external signal to disable the
batteries in the enclosure during emergency conditions. A cable is attached from the
connector to a relay band or push button typically located near the door of a computer
room. Pushing the EPO button removes power from all computer equipment in the
room and prevents the batteries from powering the server after power is removed.
EPO capabilities are required in the United States when a server is installed in a
computer room designed to comply with the special construction and fire protection
provisions of the United States’ national electrical code (or at other sites as required by
local regulations).
EMI. See electromagnetic interference (EMI).
emitter-coupled logic (ECL). A logic that expresses digital signals in differential negative
voltage levels, from -8 volts to -1.8 volts. HP NonStop™ S-series servers containing
ServerNet expansion boards (SEBs) use ECL ServerNet cables. An ECL plug-in card
(PIC) allows the modular SEB (MSEB) and I/O multifunction (IOMF) 2
customer-replaceable unit (CRU) to use ECL ServerNet cables.
emitter-coupled logic (ECL) plug-in card (PIC). A plug-in card (PIC) for the modular
ServerNet expansion board (MSEB) and I/O multifunction (IOMF) 2 customer-