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  2. Solid-state relay - Wikipedia

    en.wikipedia.org/wiki/Solid-state_relay

    A solid state relay (SSR) is an electronic switching device that switches on or off when an external voltage (AC or DC) is applied across its control terminals. They serve the same function as an electromechanical relay , but solid-state electronics contain no moving parts and have a longer operational lifetime.

  3. Stepping switch - Wikipedia

    en.wikipedia.org/wiki/Stepping_switch

    In electrical engineering, a stepping switch or stepping relay, also known as a uniselector, is an electromechanical device that switches an input signal path to one of several possible output paths, directed by a train of electrical pulses. The major use of stepping switches was in early automatic telephone exchanges to route telephone calls ...

  4. Relay - Wikipedia

    en.wikipedia.org/wiki/Relay

    A relay Electromechanical relay principle Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off. A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple ...

  5. Protective relay - Wikipedia

    en.wikipedia.org/wiki/Protective_relay

    The relays can also be classified on the type of power source that they use to work. A dual powered protection relay powered by the current obtained from the line by a CT. The striker is also shown. Self-powered relays operate on energy derived from the protected circuit, through the current transformers used to measure line current, for example.

  6. Solid State Interlocking - Wikipedia

    en.wikipedia.org/wiki/Solid_State_Interlocking

    A 'data link module' (DLM) is the interface between the data link and the TFMs. A DLM has a blue label. For transmission over longer distances, fibre-optic cable and pulse-code modulation may be used. Another type of module, the 'long distance terminal' (LDT) is available for this purpose. An LDT has a gold coloured label.

  7. Reed relay - Wikipedia

    en.wikipedia.org/wiki/Reed_relay

    (from top) Single-pole reed switch, four-pole reed switch and single-pole reed relay. Scale in centimeters. A reed relay [i] is a type of relay that uses an electromagnet to control one or more reed switches. The contacts are of magnetic material and the electromagnet acts directly on them without requiring an armature to move them.

  8. Choking emergency? How to do the Heimlich maneuver - AOL

    www.aol.com/choking-emergency-heimlich-maneuver...

    Teacher, Driving Home From Work, Pulls Over To Save Choking 100-Year-old Woman With Heimlich Maneuver. Wrap your arms around their torso from the back. Make a fist with one hand and grab it with ...

  9. List of spreadsheet software - Wikipedia

    en.wikipedia.org/wiki/List_of_spreadsheet_software

    1983, Lotus 1-2-3 for MS-DOS, the first killer application for the IBM PC, it took the market from Visicalc in the early 1980s. 1983, Dynacalc for OS-9 a Unix-like operating system, similar to VisiCalc. [11] 1984, Lotus Symphony for MS-DOS, the follow-on to Lotus 1-2-3; 1985, Boeing Calc for MVS and MS-DOS, written by subsidiary of aviation ...