Dynasonics TFXL Clamp-On Ultrasonic Flow Manuel d'utilisateur télécharger pdf (Page 21)

06-TTM-UM-00158 8/2012 21

will be in the Flow Rate Units. For unidirectional measure-

ments, set Max Flow to the highest (positive)  ow rate

expected in the piping system. For bidirectional measure-

ments, set Max Flow to the highest (positive)  ow rate

expected in the piping system.

Low Flow Cuto is provided to allow very low  ow rates

(that can be present when pumps are o and valves are

closed) to be displayed as zero  ow. Typical values that

should be entered are between 1.0% and 5.0% of the  ow

range between Min Flow and Max Flow.

Low Signal Cuto is used to drive the  ow meter and its

outputs to the value speci ed in the Substitute Flow  eld

when conditions occur that cause low signal strength. A

signal strength indication below 5 is generally inadequate for

measuring  ow reliably, so generally the minimum setting

for Low Signal Cuto is 5. A good practice is to set the Low

Signal Cuto at approximately 60-70% of actual measured

maximum signal strength.

NOTE: The factory default “Low Signal Cuto ” is 5.

If the measured signal strength is lower than the Low Signal

Cuto setting, a “Signal Strength too Low” highlighted in

red will become visible in the text area to the left in the Data

Display screen until the measured signal strength becomes

greater than the cuto value.

Signal strength indication below 2 is considered to be no

signal at all. Verify that the pipe is full of liquid, the pipe size

and liquid parameters are entered correctly, and that the

transducers have been mounted accurately. Highly aerated

liquids will also cause low signal strength conditions.

Substitute Flow is a value that the analog outputs and the

 ow rate display will indicate when an error condition in the

 ow meter occurs. The typical setting for this entry is a value

that will make the instrument display zero  ow during an

error condition.

Substitute Flow is set as a percentage between Min Flow and

Max Flow. In a unidirectional system, this value is typically

set to zero to indicate zero  ow while in an error condition.

In a bidirectional system, the percentage can be set such that

zero is displayed in an error condition. To calculate where

to set the Substitute Flow value in a bidirectional system,

perform the following operation:

100



Maximum Flow

SubstituteFlow

Maximum Flow Minimum Flow

Entry of data in the Basic and Flow tabs is all that is required

to provide  ow measurement functions to the  ow meter.

If the user is not going to utilize input/output functions,

click on the Download button to transfer the con guration

to the TFXL instrument. When the con guration has been

completely downloaded, turn the power to the meter o and

then on again to guarantee the changes take e ect.

FILTERING TAB

The Filtering tab contains several  lter settings for the TFXL

 ow meter. These  lters can be adjusted to match response

times and data “smoothing” performance to a particular

application.

Download Cancel

File Open... File Save...

System Configuration

DisplayBasic Flow

Filtering

Output Security

Flow Filter (Damping): %

Time Domain Filter:

Advanced Filter Settings:

Flow Filter Hystersis:

psecFlow Filter Min Hystersis:

303

Bad Data Rejection:

Flow Filter Sensitivity:

Factory Defaults

FIGURE 4.5  FILTERING TAB

Time Domain Filter (range 1-256) adjusts the number

of raw data sets (the wave forms viewed on the software

Diagnostics Screen) that are averaged together. Increasing

this value will provide greater damping of the data and slow

the response time of the  ow meter. Conversely, lowering

this value will decrease the response time of the meter to

changes in  ow/energy rate. This  lter is not adaptive, it is

operational to the value set at all times.

NOTE: The TFXL completes a measurement in approximately

350-400 mS. The exact time is pipe size dependent.

Flow Filter (Damping) establishes a maximum adaptive

 lter value. Under stable  ow conditions ( ow that varies less

than the Flow Filter Hysteresis entry), this adaptive  lter

will increase the number of successive  ow readings that are

averaged together up to this maximum value. If  ow changes

outside of the Flow Filter Hysteresis window, the  lter

adapts by decreasing the number of averaged readings and

allows the meter to react faster.

The damping value is increased to increase stability of the

 ow rate readings. Damping values are decreased to allow

the  ow meter to react faster to changing  ow rates. The

factory settings are suitable for most installations. Increasing

this value tends to provide smoother steady-state  ow read-

ings and outputs.

Flow Filter Hysteresis creates a window around the average

 ow measurement reading allowing small variations in

 ow without changing the damping value. If the  ow varies

within that hysteresis window, greater display damping

will occur up to the maximum values set by the Flow Filter

(Damping) entry. The  lter also establishes a  ow rate

window where measurements outside of the window

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 43 44

Commentaires sur ces manuels

Pas de commentaire

Dynasonics TFXL Clamp-On Ultrasonic Flow Manuel d'utilisateur Page 21

Commentaires sur ces manuels

Produits connexes et manuels pour Équipement Dynasonics TFXL Clamp-On Ultrasonic Flow