Overview
The velocity switch is used to indicate that the velocity has moved past the configured
setpoint, in either direction. If the velocity is below the setpoint, the velocity switch is ON.
If the velocity is above the setpoint, the velocity switch is OFF.
The velocity switch is based on the absolute value of the velocity, so it is not affected by
flow direction.
The velocity switch is implemented with a 5% hysteresis. Hysteresis defines a range around
the setpoint within which the velocity switch will not change.
Prerequisites
Depending on the communications tool you are using, you may need to configure
Channel B to operate as a discrete output, then set Discrete Output Source to Velocity Switch
before you can configure Velocity Switch Setpoint.
Procedure
Set Velocity Switch Setpoint to the value at which the velocity switch will be triggered (after
the 5% hysteresis is applied).
• If the velocity is below the setpoint, the velocity switch is ON.
• If the velocity is above the setpoint, the velocity switch is OFF.
The default value is 0.0. At this value, the velocity switch will never be ON. Velocity Switch
Setpoint can be set to 0.0 or any positive number.
Example: Velocity switch in operation
If Velocity Switch Setpoint = 5 m/sec and the first measured velocity is above 5 m/sec, the
velocity switch is OFF. 1If will remain OFF unless the velocity drops below 4.75 m/sec. If
this happens, the velocity switch will turn ON, and remain ON until the velocity rises above
5.25 m/sec. At this point it turns OFF and will remain OFF until the velocity drops below
4.75 m/sec.
Postrequisites
You can report the status of the velocity switch in the following ways:
• Setting Discrete Output Source to Velocity Switch
• Querying the device using digital communications
Related information
Configure Discrete Output Source
4.6 Set up the API referral application
The API referral application corrects line density to reference temperature and reference
pressure according to American Petroleum Institute (API) standards. The resulting process
variable is referred density.
Configure process measurement
44 Micro Motion
®
Compact Density Meters (CDM)
To Next Page
Loading...
