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  2. London Underground cooling - Wikipedia

    en.wikipedia.org/wiki/London_Underground_cooling

    Conventional air conditioning was initially ruled out on the deep lines because of the lack of space for equipment on trains and the problems of dispersing the waste heat these would generate. Different systems were proposed to cool Underground trains, including the use of large blocks of ice inside the train.

  3. 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 ...

  4. Central line (London Underground) - Wikipedia

    en.wikipedia.org/wiki/Central_line_(London...

    The Central line is a London Underground line that runs from West Ruislip or Ealing Broadway in West London to Epping in Essex or Woodford via Hainault in East London, via the East End, the City, and the West End. Printed in red on the Tube map, the line serves 49 stations over 46 miles (74 km), making it the network's longest line. [3]

  5. DIN 72552 - Wikipedia

    en.wikipedia.org/wiki/DIN_72552

    from 2nd battery and 12/24 V relay: 31 return to battery- or direct to ground 31a return to battery- 12/24 V relay 31b return to battery- or ground through switch 85d 31c return to battery- 12/24 V relay 31, 31a Electric motors; 32 return 31 33 main terminal (swap of 32 and 33 is possible) 30 33a limit 33b field 54e 33f 2. slow rpm: 33g 3. slow ...

  6. Zero-crossing control - Wikipedia

    en.wikipedia.org/wiki/Zero-crossing_control

    The point where the AC line voltage is zero is the zero cross point. When a TRIAC is connected in its simplest form, it can clip the beginning of the voltage curve, due to the minimum gate voltage of the triac. A zero-cross circuit works to correct this problem, so that the TRIAC functions as well as possible.

  7. Contactor - Wikipedia

    en.wikipedia.org/wiki/Contactor

    AC contactor for pump application. A contactor is an electrically controlled switch used for switching an electrical power circuit. [1] A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 230-volt motor switch.

  8. Fan clutch - Wikipedia

    en.wikipedia.org/wiki/Fan_clutch

    A fan clutch is a thermostatic engine cooling fan that can freewheel at low temperatures when cooling is not needed, allowing the engine to warm up faster, relieving unnecessary load on the engine. As temperatures increase, the clutch engages so that the fan is driven by engine power and moves air to cool the engine.

  9. Fan coil unit - Wikipedia

    en.wikipedia.org/wiki/Fan_coil_unit

    A fan coil unit (FCU), also known as a Vertical Fan Coil Unit (VFCU), is a device consisting of a heat exchanger (coil) and a fan. FCUs are commonly used in HVAC systems of residential, commercial, and industrial buildings that use ducted split air conditioning or central plant cooling.