JAOMAD Glossary Z:
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Z—Means "Position," “Dimension” when used in first alpha character position of ISA instrument function tag, means "Z-axis" when used as modifier, means "Driver," "Actuator," or "Unclassified Final Control Element" when used in any succeeding position [see ANSI/ISA S5.1-1984 (R1992)]; also: in electrical devices and systems, means electrical impedance.
Zin—In instrumentation devices, means input impedance, which generally should be very high to prevent signal loss across input transducer; consists of parallel combination of input resistance and input capacitance, which at frequencies over a few hundred Hertz causes capacitance to dominate.
ZD—Means "Gauging Deviation" when used in first two alpha character positions of ISA instrument function tag [see ANSI/ISA S5.1-1984 (R1992)].
Zeal—Human enthusiasm which is always at its height at the commencement of an undertaking [from Thucydides, The Peloponnesian War, Book II, chapter 8]. J
Zero Adjustment—Ability to adjust display of process signal on some meter so display reads zero at some other value, such as 4mA or 1Vdc, so as to have a “live” zero.
Zero Cross Fire—Method of controlling power that provides output switching only at or near the zero-voltage crossing points of the AC sine wave; often called Burst Fire and Zero Voltage Switching; see Burst Fire.
Zero Insertion—In SDLC digital transmission, process of including binary 0 in transmitted data stream to avoid confusing data and SYN characters, removing inserted 0 at receiving end,
Zero Offset—Difference expressed in degrees between true zero and an indication given by the measuring device.
Zero Power Resistance—Resistance of thermistor or RTD element with no power being dissipated.
Zero Shift—Error due to changes in ambient conditions in which zero output shifts; thus entire calibration curve moves in a parallel displacement.
Zero Suppression—Span of indicator or recorder may be offset from zero (zero suppressed) such that neither limit of the span will be zero; for example, temperature indicator which displays 100° span from 200° to 300° is said to have 200° zero suppression.
Zero Voltage Switching, Zero Switching—Making or breaking of circuit which is timed so that the transition occurs when voltage wave form crosses zero voltage; typically found only in solid state switching devices; see Zero Cross Fire, Burst Fire.
ZIF—Zero Insertion Force socket; standard integrated circuit socket design in which user moves lever to add or replace chips, reducing chance of damage to pins.
ZigBee—Pioneered by Philips Semiconductors, wireless network used for monitoring and control systems originally defined by Motorola and conforming to the IEEE 802.15.4 standard for low data rate networks, generally provide transmission speeds of 20, 40 and 250 Kbps over a range of 10 to 100 meters and can be configured in star, mesh or peer-to-peer topologies; networks use considerably less power than Wi-Fi or Bluetooth and are designed for industrial automation, building automation and home control. Such applications require simple control networks that periodically send small packets from sensors and switches to regulate and turn devices on and off.
ZigBee Alliance—Association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control products based on an open global standard.
ZIP—Zig-Zag Inline Package; chip package similar to DIP, but both rows of pins come out of one side in alternating pattern; also: to compress a file with PKZIP®; also: removable disk from Iomega®; also: proprietary messaging protocol from IBM®.
ZOH—Zero Order Hold; in sampled data systems, device which maintains memory of control signal values between samples, as in digital-to-analog output to control valve.
Zooming—In computer graphics, causing object on video screen to appear smaller or larger by moving window and specifying various window sizes; see Digital Zoom, Optical Zoom.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Intro