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225:. With hysteresis, there is no deadband and so the output is always in one direction or another. Devices with hysteresis have memory, in that previous system states dictate future states. Examples of devices with hysteresis are single-mode thermostats and smoke alarms. Deadband is the range in a process where no changes to output are made. Hysteresis is the difference in a variable depending on the direction of travel.
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exhibit hysteresis. For example, the furnace in the basement of a house is adjusted automatically by the thermostat to be switched ON as soon as the temperature at the thermostat falls to 18 °C and the furnace is switched OFF by the thermostat as soon as the temperature at the thermostat reaches
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A thermostat which sets a single temperature and automatically controls both heating and cooling systems without a mode change exhibits a deadband range around the target temperature. The low end of the deadband is just above the temperature where the heating system turns on. The high end of the
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within certain predetermined limits, but there is a range of voltage in-between during which no changes are made, such as between 112 and 118 volts (the deadband is 6 volts), or between 215 to 225 volts (deadband is 10 volts).
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systems. If mechanical backlash eliminators are not available, the control can compensate for backlash by adding the deadband value to the position vector whenever direction is reversed.
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or signal processing system where the output is zero (the output is 'dead' - no action occurs). Deadband regions can be used in control systems such as
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generally also have backlash and hence a deadband, which must be taken into account when making position adjustments, especially with
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205:) exhibit deadband. There is no drive from the input to the output shaft in either direction while the teeth are not meshed.
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22 °C. There is no temperature at which the house is not being heated or allowed to cool (furnace on or off).
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Johnson, Curtis D. "Process
Control Instrumentation Technology", Prentice Hall (2002, 7th ed.)
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deadband is just below the temperature where the air-conditioning system starts.
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308:. Department of Chemical and Process Engineering, University of Strathclyde
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335:(2nd ed.). New Delhi: Prentice-Hall of India. pp. 15–16.
272:"Dead Band Plus Hysteresis Estimation with ValveLink Diagnostics"
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systems). A form of deadband that occurs in mechanical systems,
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or repeated activation-deactivation cycles (called 'hunting' in
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93:Deadband is the period of dead-state of a system.
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46:but its sources remain unclear because it lacks
281:. Fisher Controls International. October 2012
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156:Input and output of the deadband operator.
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77:Learn how and when to remove this message
16:Band of input values yielding zero output
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332:Transducers & Instrumentation
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306:Introduction to Process Control
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217:Hysteresis versus Deadband
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32:This article includes a
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329:Murty, D.V.S. (2009).
300:Postlethwaite, Bruce.
199:Gear teeth with slop (
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184:Backlash (engineering)
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233:Simple (single mode)
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182:Further information:
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135:proportional control
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161:Voltage regulators
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34:list of references
139:compound machines
119:transfer function
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111:neutral zone
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67:January 2013
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53:Please help
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235:thermostats
229:Thermostats
143:gear trains
131:oscillation
129:to prevent
59:introducing
348:18 January
312:18 January
285:18 January
258:References
223:hysteresis
207:Leadscrews
167:regulators
107:dead zone
103:dead-band
361:Category
246:See also
202:backlash
193:Backlash
178:Backlash
147:backlash
141:such as
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171:voltage
55:improve
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275:(PDF)
121:in a
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