详细介绍:
台仪温控器FU86-101000西安一级代理商
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Modulating valves normally require a special “Three Point Stepping” control algorithm. This
which provides an output to move the valve further open, or further closed whenever there is
a control deviation error. When this error is zero, no further output is required to maintain
control unless load conditions change. This type of controller is often called a Valve Motor
Drive controller. This instrument does not currently have a three point stepping algorithm.
However, modulating valves that have a valve positioning circuitry to adjust the valve position
from a DC linear mA or voltage output signal can be controlled.
Also refer to: Control Deviation, Linear Output, Modulating Valve, and Valve Motor Control
Time Proportioning Control
Time proportioning control is accomplished by cycling the output on and off during the
prescribed cycle time, whenever the process variable is within the proportional band(s). The
PID control algorithm determines the ratio of time (on vs. off) to achieve the level of the
correcting variable required to remove the control deviation error. E.g. for a 32 second cycle
time, 25% power would result in the output turning on for 8 seconds, then off to 24 seconds.
This type of output might be used with electrical contactors, solid state relays or solenoid
valves. Time proportioning control can be implemented with Relay, Triac or SSR Driver
outputs for either primary or secondary outputs.
Also refer to: Control Deviation, Correcting Variable, Current Proportioning Control, Cycle
Time, PID, Primary Proportional Band, Relay, Secondary Proportional Band, Solenoid Valve,
SSR and Triac.
Trend Display
Trend View is a graphical representation of recent process conditions. This feature is
available on all variants. It does not rely on the Data Recorder option, and does not retain the
stored data if the power is turned off. The trend shows the most recent 120 out of 240 stored
data points. Its scale adjusts automatically for the best resolution for the visible data. This
data can be the process variable; process variable & setpoint (shown as a doted line), or the
minimum and maximum value of the process variable measured since the last sample. Any
active alarm(s) are indicated above the graph. The user can scroll the right hand cursor line
back to examine all 240 data points. The sample interval and data to display is set in Display
Configuration.
Also refer to: Alarm Types, Display Configuration, Operation Mode, and Process Variable,
Setpoint.
Trend Display
Trend View is a graphical representation of recent process conditions. This feature is
available on all variants. It does not rely on the Data Recorder option, and does not retain the
stored data if the power is turned off. The trend shows the most recent 120 out of 240 stored
data points. Its scale adjusts automatically for the best resolution for the visible data. This
data can be the process variable; process variable & setpoint (shown as a doted line), or the
minimum and maximum value of the process variable measured since the last sample. Any
active alarm(s) are indicated above the graph. The user can scroll the right hand cursor line
back to examine all 240 data points. The sample interval and data to display is set in Display
Configuration.
Also refer to: Alarm Types, Display Configuration, Operation Mode, and Process Variable,
Setpoint.
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