Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 196)

Glossary-9
NEC The National Electrical Code are recommendations of the National Fire Protection
Association and is revised every three years. City or state regulations may diffe
from code regulations and take precedence over NEC rules.
NEMA The National Electrical Manufacturers Association is a non-profit organization
organized and supported by manufacturers of electrical equipment and supplies.
Some of the standards NEMA specifies are: HP ratings, speeds, frame sizes and
dimensions, torques and enclosures.
NEMA Standards Consensus standards in the United States for electrical equipment approved by the
members of the National Electrical Manufacturers Association.
Network A series of stations (nodes) connected by some type of communication medium. A
network may be made up of a single link or multiple links.
Noise Unwanted disturbances imposed upon a signal that tend to obscure its data content.
Normally Closed Contacts A set of contacts on a relay or switch that are closed when the relay is de-energized
or the switch is de-activated. They are open when the relay is energized or the
switch is activated.
Normally Open Contacts A set of contacts on a relay or switch that are open when the relay is de-energized
or the switch is de-activated. They are closed when the relay is energized or the
switch is activated.
Off 1. A term used to designate the 0 state of a bit; the inoperative state of a device;
the state of a switch or circuit that is open. Designated by the symbol 0.
2. The opposite of On.
Offline Describes equipment or devices not under direct control and not directly
controlling. When equipment is either idle, undergoing repair, or performing a task
under its own direction, it is said to be “off line.”
On 1. A term used to designate the 1 state of a bit; the operative state of a device;
the state of a switch or circuit that is closed. Designated by the symbol 1.
2. The opposite of Off.
Online Refers to equipment or devices that are in direct interactive communication.
Open-loop System A control system that has no means of comparing the output with the input for
control purposes.
Open Machine (Motors) A machine having ventilating openings which permit passage of external cooling
air over and around the winds of the machine.
• Drip-proof Machine – is an open type machine in which the ventilating
openings are so constructed that successful operation is not interfered with
when drops of liquid or solid particles strike or enter the enclosure at any angl
from one to fifteen degrees downward from vertical.