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SA (Substation Automation): in which hard-wired substation components are replaced by digital equipment such as RTUs, IEDs, networks, and software applications.
SCADA (Supervisory Control and Data Acquisition): SCADA systems are used by utility operators or dispatchers to monitor and control many different devices, via communications to remote sites which have RTUs or IEDs capable of reporting data from physical devices, and issuing control commands to them.
Scalability: The ability to expand a computing solution to support large numbers of users without impacting performance.
Scale: Multiplier used to convert a value from the measured value to the appropriate engineering units.
Schedule: The specification of intended energy flow over transmission facilities. Schedules are stated in MW for a given time.
Scheduling Coordinators:
Entities certified by the Federal Energy Regulatory Commission that
act as a go-between with the Independent System Operator on behalf of
generators, supply aggregators (wholesale marketers), retailers, and
customers to schedule the distribution of electricity. [DOE
Glossary of Electricity Terms]
Scheduled Outage: The shutdown
of a generating unit, transmission line, or other facility, for
inspection or maintenance, in accordance with an advance schedule.
[DOE
Glossary of Electricity Terms]
SDSL: Symmetric (or single-line) Digital Subscriber Line is the same as HDSL, but uses only one single twisted pair cable. See also xDSL.
Search Engine: A program, which indexes and retrieves web sites based on keywords input by a user. Search engines rely on automated programs, variously known as spiders or robots, to index sites on the Internet according to keywords. No human evaluation is conducted to determine the relevancy of sites. Rather, the software relies on Boolean logic to deliver search results based on the occurrence of words or search terms entered by the user.
Secret Key Cryptography: Data encrypted and decrypted with same (symmetrical) key. It is the traditional way of encrypting messages; e.g., Caesar cypher, one-time pad, Enigma. It is a fast method with tested algorithms available; e.g., DES, RC4, IDEA. Strength of scheme largely depends on size of key. Weakness of the method is the distribution of the keys. Public Key Cryptography can be used for key distribution; e.g., PGP.
Secured Electronic Transaction (SET): Standard for electronic shopping with payment cards over the Internet.
Security Policy: A set of rules that apply to all security-related areas and activities in a particular security domain. A policy should include the purpose for security, organizational security issues, and cyber technologies.
Select Before Operate (SBO): A two step device control mechanism consisting of the Select service followed by a Control/Operate service. The Select service is used to arm the device. The device enters the SELECTED state for some period of time. The Control service is used to carry out a control command if and only if the device is SELECTED for the issuing client. This sequence has the effect that a client can lock-out other clients from operating a point during a pre-determined period of time so that it is the only client that can operate that point during that time.
Self-extracting Archive: A file that contains other files compressed into a single archive. When opened, the self-extracting archive will decompress those files automatically and place them where specified, either by the user or the archive itself. The two most common file extensions used for self-extracting archives are .exe on PC's and .sea on Macintosh.
Semantics: Meaning of the information or data.
Sequence Of Events (SOE): Sequence Of Events is an ordered, timestamped log of the state changes of binary inputs (also known as status inputs). Used to recreate or analyze the behavior of utility power, gas, or water systems over a period of time.
Server: A computer that shares its resources, such as printers and files, with other computers on the network but is used only to store and retrieve information.
Server Farm: A group of servers that are linked together as a ‘single system image’ to provide centralized administration and horizontal scalability.
Server Security: The hardening of a server’s operating system. This includes turning off unnecessary services, keeping the system up-to-date with the latest security and OS patches, etc. See Host-Based Security.
Server-based Computing: An innovative, server-based approach to delivering business-critical applications to end-user devices, whereby an application’s logic executes on the server and only the user interface is transmitted across a network to the client. Its benefits include single-point management, universal application access, bandwidth-independent performance, and improved security for business applications.
Service Level Agreement: A Service Level Agreement (SLA) is a contract between a network service provider and a customer that specifies, usually in measurable terms, what services the network service provider will furnish. A network service provider may be an external company or another department within the customer's company. Some metrics that SLAs may specify include:
- What percentage of the time services will be available
- The number of users that can be served simultaneously
- Specific performance benchmarks to which actual performance will be compared, such as available bandwidth, average and peak response times, number and duration of permanent and temporary failures, mean time to repair/correct a failure, percent of messages lost or requiring retransmission, etc.
- The schedule for notification in advance of network changes that may affect users
- Help desk response time for various classes of problems
- Dial-in access availability
- Usage statistics that will be provided
Servlet: JavaTM Servlet technology provides web developers with a simple, consistent mechanism for extending the functionality of a web server and for accessing existing business systems. A servlet can almost be thought of as an applet that runs on the server side -- without a face. Servlets are the Java platform technology of choice for extending and enhancing web servers. Servlets provide a component-based, platform-independent method for building web-based applications, without the performance limitations of CGI programs. And unlike proprietary server extension mechanisms (such as the Netscape Server API, ISAPI, or Apache API), servlets are server- and platform-independent. See also J2EE. More...
Session Layer: Layer five of the OSI reference model; responsible for the establishment, management, and termination of logical connections between two end users.
SGML (Standard Generalized Markup Language): SGML is a system for organizing and tagging elements of a document. SGML was developed and standardized by the ISO in 1986 (ISO 8879:1986). SGML itself does not specify any particular formatting; rather, it specifies the rules for tagging elements. These tags can then be interpreted to format elements in different ways. More... See also HTML and XML.
Shareware: Software which has been released by its author to the general public to try out before buying. It is expected that if a user likes the shareware software, that user will send the author the requested fee. Shareware is not free and is almost always protected by copyrights.
S-HTTP: Secure HTTP is a secure message-oriented communications protocol designed for use in conjunction with HTTP in order to enable spontaneous commercial transactions for a wide range of applications. It is implemented as a Layer 7 security protocol.
Shunt Capacitance (pFft): The amount of equivalent capacitive load of the cable, typically listed in a per foot basis. One of the factors limiting total cable length is the capacitive load. Systems with long lengths benefit from using low capacitance cable.
SI: Scheduling Infrastructure
SIDF: System Independent Data Format
Signal: Electromagnetic waves propagated along a transmission medium. Signals can be either analog or digital. Analog signals can have any value in a range, while digital signals can only have a limited number of values. The enemies of both analog and digital signals include attenuation, noise, and crosstalk. Attenuation is the tendency of a signal to get weaker with distance. Analog signals must be amplified before they become too diminished to be detectable. Unfortunately, analog signals accumulate noise with repeated amplification. Digital signals, while they are degraded by attenuation, can be detected and repeated indefinitely with no loss of data.
Signal-To-Noise Ratio: When used in reference to Usenet activity, it describes the relation between amounts of actual information in a discussion, compared to its quantity.
Signature: Text which is automatically attached to the end of each e-mail sent out. This text may be contained within the e-mail client itself or in a text file residing elsewhere on the computer.
sit: The most common archive format used on the Macintosh.
SI Units (International System of Units): The modern form of the metric system, which has been adopted by the United States and most other nations. Note: The SI is constructed from seven base units for independent physical quantities. Tables showing these values are included below and are current as of Fall 1995.
| Multiplication Factor | Prefix Name | Prefix | Symbol |
|---|---|---|---|
| 1 000 000 000 000 000 000 000 000 = | 1024 | yotta | Y |
| 1 000 000 000 000 000 000 000 = | 1021 | zetta | Z |
| 1 000 000 000 000 000 000 = | 1018 | exa | E |
| 1 000 000 000 000 000 = | 1015 | peta | P |
| 1 000 000 000 000 = | 1012 | tera | T |
| 1 000 000 000 = | 109 | giga | G |
| 1 000 000 = | 106 | mega | M |
| 1 000 = | 103 | kilo | k |
| 100 = | 102 | hecto | h |
| 10 = | 101 | deka | da |
| 0.1 = | 10-1 | deci | d |
| 0.01 = | 10-2 | centi | c |
| 0.001 = | 10-3 | milli | m |
| 0.000 001 = | 10-6 | micro |  |
| 0.000 000 001 = | 10-9 | nano | n |
| 0.000 000 000 001 = | 10-12 | pico | p |
| 0.000 000 000 000 001 = | 10-15 | femto | f |
| 0.000 000 000 000 000 001 = | 10-18 | atto | a |
| 0.000 000 000 000 000 000 001 = | 10-21 | zepto | z |
| 0.000 000 000 000 000 000 000 001 = | 10-24 | yocto | y |
| Quantity | Unit Name | Unit Symbol |
|---|---|---|
| length | meter | m |
| mass | kilogram | kg |
| time | second | s |
| electric current | ampere | A |
| thermodynamic temperature | kelvin | K |
| amount of substance | mole | mol |
| luminous intensity | candela | cd |
| Quantity | Unit Name | Unit Symbol | Expression in Terms of Other SI Units |
|---|---|---|---|
| Absorbed dose, specific energy imparted, kerma, absorbed dose index | gray | Gy | J/kg |
| Activity (of a radionuclide) | becquerel | Bq | 1/s |
| Celsius temperature | degree Celsius |  C |
K |
| Dose equivalent | sievert | Sv | J/kg |
| Electric capacitance | farad | F | C/V |
| Electric charge, quantity of electricity | coulomb | C | A•s |
| Electric conductance | siemens | S | A/V |
| Electric inductance | henry | H | Wb/A |
| Electric potential, potential difference, electromotive force | volt | V | W/A |
| Electric resistance | ohm |  |
V/A |
| Energy, work, quantity of heat | joule | J | N•m |
| Force | newton | N | kg•m/s2 |
| Frequency (of a periodic phenomenon) | hertz | Hz | 1/s |
| Illuminance | lux | lx | lm/m2 |
| Luminous flux | lumen | lm | cd•sr |
| Magnetic flux | weber | Wb | V•s |
| Magnetic flux density | tesla | T | Wb/m2 |
| Plane angle | radian | rad | m/m |
| Power, radiant flux | watt | W | J/s |
| Pressure, stress | pascal | Pa | N/m2 |
| Solid angle | steradian | sr | m2/m2 |
SLIP (Serial Line Internet Protocol): An older protocol for IP connections over telephone lines, RS-232 cables, or other serial lines. The Point-to-Point Protocol (PPP) is replacing it.
Small Power Producer (SPP): Under the Public Utility Regulatory Policies Act (PURPA), a small power production facility (or small power producer) generates electricity using waste, renewable (water, wind and solar), or geothermal energy as a primary energy source. Fossil fuels can be used, but renewable resource must provide at least 75 percent of the total energy input. (See Code of Federal Regulations, Title 18, Part 292.) [DOE Glossary of Electricity Terms]
Smart Card: A digitally encoded card, similar to a credit card, usually containing a variety of information about the individual(s) authorized to use it. Note: The information can be accessed by a card reader into which the card is inserted. The information may include access codes (for opening doors), account numbers (merchant account numbers as well as banking account numbers), and electronic cash (which is withdrawn from the card as a purchase is made). From T1 Glossary 2000: Glossary of Telecommunications Terms.
SMB (Server Message Block): An application layer protocol for sharing files, printers, serial ports, and communications abstractions. It was developed by IBM and later enhanced by Microsoft and Intel. Microsoft has offered a public or open source version of SMB for the Internet to the IETF, called the Common Internet File System (CIFS).
SMI (Structure of Management Information): Defines the adapted subset of the OSI's Abstract Syntax Notation One, ASN.1 (ISO/IEC 8824), used to write MIB modules. SMI also assign a set of associated administrative values. SMI is part of the SNMP framework. SMIv2 is defined in RFC2578, RFC2579, and RFC2580.
SMTP (Simple Mail Transfer Protocol): An application layer message transfer TCP/IP protocol. The Internet standard protocol for transferring electronic mail messages from one computer to another. SMTP specifies how two mail systems interact and the format of control messages they exchange to transfer mail. Defined in RFC2821 with message format description in RFC2822. See RFC1123 and MIME. See also RFC1652, RFC1870, RFC1891, RFC1893, RFC1894, RFC1985, RFC2034, RFC2476, RFC2487, RFC2505, RFC2554, RFC2645, RFC2846, RFC2852, RFC2920, and RFC3030. Yahoo! Directory. Format.
Smurf DoS Attack: The two main components to the smurf denial-of-service attack are the use of forged ICMP echo request packets and the direction of packets to IP broadcast addresses. In the "smurf" attack, attackers are using ICMP echo request packets directed to IP broadcast addresses from remote locations to generate denial-of-service attacks. There are three parties in these attacks: the attacker, the intermediary, and the victim (note that the intermediary can also be a victim). The intermediary receives an ICMP echo request packet directed to the IP broadcast address of their network. If the intermediary does not filter ICMP traffic directed to IP broadcast addresses, many of the machines on the network will receive this ICMP echo request packet and send an ICMP echo reply packet back. When (potentially) all the machines on a network respond to this ICMP echo request, the result can be severe network congestion or outages. When the attackers create these packets, they do not use the IP address of their own machine as the source address. Instead, they create forged packets that contain the spoofed source address of the attacker's intended victim.
SNA (Systems Network Architecture): IBM network protocols originally developed for mainframes. More... and More...
Snail Mail: Mail sent through the US Post Office.
SNAP (SubNetwork Addressing Protocol): The SNAP protocol was introduced to allow an easy transition to the new Logical Link Control (LLC) frame format for vendors. SNAP allows older frames and protocols to be encapsulated in a Type 1 LLC header so making any protocol 'pseudo-IEEE compliant'. SNAP is described in RFC1042.
Sniffing: The process of monitoring data traveling over a network. Sniffing can be used both for legitimate network management functions and for stealing information off a network.
SNMP (Simple Network Management Protocol): An application layer network management TCP/IP protocol. Originally designed to be used in managing TCP/IP internets. SNMP is presently implemented on a wide variety of computers and networking equipment and may be used to manage many aspects of network and end-station operation.
SOAP (Simple Object Access Protocol): is a lightweight protocol for exchange of information in a decentralized, distributed environment. It is an XML-based protocol that consists of three parts: an envelope that defines a framework for describing what is in a message and how to process it, a set of encoding rules for expressing instances of application-defined datatypes, and a convention for representing remote procedure calls and responses. Submitted to the W3C by Microsoft and IBM; Simple Object Access Protocol (SOAP) 1.1. See also UDDI and WSDL.
Socket Address: IP address together with a port number, separated by a semicolon.
SONET (Synchronous Optical NETwork): A set of standards developed by ANSI for high-speed data communication over fiber optic cable at speeds between 51.84 Mbps and 13 Gbps. .
Source-Route Translational Bridging: Sometimes referred to as SR/TLB, a method of bridging where source-route stations can communicate with transparent bridge stations with the help of an intermediate bridge that translates between the two bridge protocols.
Source-Route Transparent Bridging: A bridging scheme proposed by IBM that attempts to merge the two most prevalent bridging strategies (transparent and source-route bridging). SRT, as it is sometimes referred to, employs both technologies in one device to satisfy the needs of all end nodes. No translation between the bridging protocols is done, as compared to source-route translational bridging (SR/TLB).
Spam: A slang term, not to be confused with the meat product, which refers to the sending of hundreds if not thousands of unsolicited messages. Spam can be sent to newsgroups, mailing lists, and to individuals. Spam is highly frowned upon. Spam got its name from the Monty Python Flying Circus skit.
Special Protection System (SPS): an automatic protection system (also known as a remedial action scheme) designed to detect abnormal or predetermined system conditions, and take corrective actions other than and/or in addition to the isolation of faulted components to maintain system reliability. Such action may include changes in demand, generation (MW and Mvar), or system configuration to maintain system stability, acceptable voltage, or power flows. An SPS does not include (a) underfrequency or undervoltage load shedding or (b) fault conditions that must be isolated or (c) out-of-step relaying (not designed as an integral part of an SPS). (NERC "Terms and Their Definitions As Used in the NERC Planning Standards")
Spider: A program which scurries around the Internet collecting information about web sites and reporting that information back to a database. Spiders (or bots) are often used by search engines to index the web sites for later searching.
Spinning Reserve: That
reserve generating capacity running at a zero load and synchronized to
the electric system. [DOE
Glossary of Electricity Terms]
Spot Purchases: A single shipment
of fuel or volumes of fuel, purchased for delivery within 1 year. Spot
purchases are often made by a user to fulfill a certain portion of
energy requirements, to meet unanticipated energy needs, or to take
advantage of low-fuel prices. [DOE
Glossary of Electricity Terms]
Spoofing: see IP Spoofing.
Spread Spectrum Modulation: Spread Spectrum Modulation, which is a Physical Layer function, is a process in which the radio transceiver prepares the digital signal within the NIC for transmission over the airwaves. Spread spectrum "spreads" a signal's power over a wider band of frequencies, sacrificing bandwidth in order to gain signal-to-noise performance (referred to as process gain). This contradicts the desire to conserve frequency bandwidth, but the spreading process makes the data signal much less susceptible to electrical noise than conventional radio modulation techniques. Other transmission and electrical noise, typically narrow in bandwidth, will only interfere with a small portion of the spread spectrum signal, resulting in much less interference and less errors when the receiver demodulates the signal.
Spread Spectrum using Frequency Hopping: Frequency hopping works very much like its name implies. It takes the data signal and modulates it with a carrier signal that hops from frequency to frequency as a function of time over a wide band of frequencies. With frequency hopping spread spectrum, the carrier frequency changes periodically. The frequency hopping technique reduces interference because an interfering signal from a narrowband system will only affect the spread spectrum signal if both are transmitting at the same frequency at the same time. Thus, the aggregate interference will be very low, resulting in little or no bit errors. A frequency hopping radio, for example, will hop the carrier frequency over the 2.4 GHz frequency band between 2.4 GHz and 2.483 GHz.
Spread Spectrum - Direct Sequence: Direct sequence spread spectrum combines a data signal at the sending station with a higher data rate bit sequence, which many refer to as a chipping code (also known as processing gain). A high processing gain increases the signals resistance to interference. The minimum linear processing gain that the FCC allows is 10, and most commercial products operate under 20. The IEEE 802.11 Working Group has set their minimum processing gain requirements at 11. In comparison to frequency hopping, direct sequence can achieve much higher than 2 Mbps data rates.
SQL (Structured Query Language): SQL is used to query databases for specific information.
SSI (Server Side Includes): A popular extension to HTML. SSI allows the embedment of a number of special 'commands' into the HTML itself. All directives to the server are formatted as SGML comments within the document. The web server will then interpret the commands and execute them dynamically. Google Directory. Yahoo! Directory.
SSL (Secure Socket Layer): A Public Key Infrastructure (PKI) based protocol used for authenticated and encrypted communication between clients and servers developed by Netscape Communications. See also TLS.
SSTP (Double Shielded Twisted Pair): Cable with each pair enclosed in a foil wrap and the the entire four pairs enclosed in a braided sheath. Sometimes referred to as PiMF (“pairs in metal foil”). See Category 7.
Standalone Program: A program that does not interact with any other program.
Start Page: Also called the Home Page, it is the page that pops up when you first start up your web browser.
Stateless: Having no information about what occurred previously.
Stateful Inspection: Also referred to as dynamic packet filtering. Stateful inspection is a firewall architecture that operates at the network layer. Unlike static packet filtering, which examines a packet based on the information in its header, stateful inspection examines not just the header information but also the contents of the packet up through the application layers in order to determine more about the packet than just information about its source and destination. A stateful inspection firewall also monitors the state of the connection and compiles the information in a state table. Because of this, filtering decisions are based not only on administrator-defined rules (as in static packet filtering) but also on context that has been established by prior packets that have passed through the firewall.
Static Stability (Local Stability) - Ability of the system to maintain synchronous operation of the generating units with minor disturbance of the operating conditions (of a low amplitude and a low rate of increase).
Store and Forward: Describes network operations where messages, packets, or frames are temporarily stored in one or more intermediate nodes before reaching their final destination.
STP (Shielded Twisted Pair): Twisted-pair cable enclosed in a foil or braid shield that protects against electromagnetic interference.
Stranded Costs: Prudent costs incurred by a utility which may not be recoverable under market-based retail competition. Examples are undepreciated generating facilities, deferred costs, and long-term contract costs. [DOE Glossary of Electricity Terms]
Stream: Contiguous sequence of bits, representing a stream of data, transmitted continuously over a communications path, serially (one at a time). Opposite to file.
Subnetwork: Collection of equipment and physical media, which can be used to interconnect other systems for the purpose of communications between them. Subnetworks may be interconnected with each other via network systems operating at the network layer or above.
Subnetwork Address: The information needed to identify a particular real system attached to a subnetwork (e.g., token ring adapter address).
Substation: Facility equipment that switches, changes, or regulates electric voltage. [DOE Glossary of Electricity Terms]
Summarize: To encapsulate a number of responses into one coherent usable message. Often done on controlled mailing lists or active newsgroups, to help reduce bandwidth.
Supervisory Control and Data Acquisition System (SCADA) - refers to a system that acquires data from field devices and is used to issue control commands to devices. It is the primary system used by power system operators to monitor and control the power system.
Surfing the Internet: Slang for getting on the Internet and more specifically, browsing web pages.
Switch: Networking device that provide bridging functionality. See also Bridge.
Switching Station: Facility
equipment used to tie together two or more electric circuits through
switches. The switches are selectively arranged to permit a circuit to
be disconnected, or to change the electric connection between the
circuits. [DOE
Glossary of Electricity Terms]
System (Electric): Physically
connected generation, transmission, and distribution facilities
operated as an integrated unit under one central management, or
operating supervision. [DOE
Glossary of Electricity Terms]
Symmetric Key Cryptography: See Secret Key Cryptography
SYN Flood DoS Attack: When a system (called the client) attempts to establish a TCP connection to a system providing a service (the server), the client and server exchange a set sequence of messages. This connection technique applies to all TCP connections--telnet, Web, email, etc. The client system begins by sending a SYN message to the server. The server then acknowledges the SYN message by sending SYN-ACK message to the client. The client then finishes establishing the connection by responding with an ACK message. The connection between the client and the server is then open, and the service-specific data can be exchanged between the client and the server. Here is a view of this message flow:The potential for abuse arises at the point where the server system has sent an acknowledgment (SYN-ACK) back to client but has not yet received the ACK message. This is what we mean by half-open connection. The server has built in its system memory a data structure describing all pending connections. This data structure is of finite size, and it can be made to overflow by intentionally creating too many partially-open connections. Creating half-open connections is easily accomplished with IP spoofing. The attacking system sends SYN messages to the victim server system; these appear to be legitimate but in fact reference a client system that is unable to respond to the SYN-ACK messages. This means that the final ACK message will never be sent to the victim server system. The half-open connections data structure on the victim server system will eventually fill; then the system will be unable to accept any new incoming connections until the table is emptied out. Normally there is a timeout associated with a pending connection, so the half-open connections will eventually expire and the victim server system will recover. However, the attacking system can simply continue sending IP-spoofed packets requesting new connections faster than the victim system can expire the pending connections. In most cases, the victim of such an attack will have difficulty in accepting any new incoming network connection. In these cases, the attack does not affect existing incoming connections nor the ability to originate outgoing network connections. However, in some cases, the system may exhaust memory, crash, or be rendered otherwise inoperative. The location of the attacking system is obscured because the source addresses in the SYN packets are often implausible. When the packet arrives at the victim server system, there is no way to determine its true source. Since the network forwards packets based on destination address, the only way to validate the source of a packet is to use input source filtering.
Synchronization - Operation that consists in connection of the generating unit to the power system or connection of different power systems after their frequencies, phases and voltages are equalized to reduce the disparity of the vectors of connected voltages to a value close to zero.
Synchronous Transmission: Data communications in which transmissions are sent at a fixed timing rate, with the sending and receiving devices synchronized.
Syntax: Grammar or structure rules, which must be adhered to by a language (e.g., a transfer syntax defines the formatting rules for transferring data from one system to another).
Sysop: The system operator of a BBS. It can also refer to anyone in charge of a system on the Internet.
System: 1. Any organized assembly of resources and procedures united and regulated by interaction or interdependence to accomplish a set of specific functions. 2. A collection of personnel, equipment, and methods organized to accomplish a set of specific functions.
System Integration: The progressive linking and testing of system components to merge their functional and technical characteristics into a comprehensive, interoperable system. Note: Integration of data systems allows data existing on disparate systems to be shared or accessed across functional or system boundaries.