Siemens SITRANS FUS1010 NEMA-4X/ IP 65 manual Zero Crossover Adjustment Hot Key

Section 2 1010NFM-3J

To adjust the Tn mark position press the <3> key on the keypad to bring up the [TnSet] command. Pressing the <+> or <-> keys will cause the Tn marker to move later or earlier, respectively. The change from the default value (in samples) will appear in the number to the right of the command. As you adjust the Tn marker, both Tn and Vs (liquid sound velocity) will change accordingly. To exit this mode, press the <0> key on the keypad.

Zero Crossover Adjustment: (Hot Key 4)

Observe the small “X” mark located on the zero crossing line near the middle of the receive signal in the Graph Screen above. This “X” indicates the central crossover which the 1010 is using to measure the transit-time delta. This crossover will generally be close to the peak of the receive signal with at least one well formed (non-aberrated) receive cycle on each side of the crossover. If it appears that the placement of this crossover is unsatisfactory then it can be adjusted by pressing the <4> key on the keypad, which will invoke the [ZCOSet] command. The crossover point can then be moved in either direction on the waveform using the <+> or <-> keys. The change from the default value (in receive cycles) will appear in the number to the right of the command. To exit this mode, press the <0> key.

Envelope Threshold Adjustment: (Hot Key 5 & 6)

Pressing the <=> key causes the graph to toggle between the default signal waveform screen and the signal envelope screen (see example below). This envelope screen can aid in the diagnosis of Tn errors caused by unusual receive waveform distortion. Signal distortion is sometimes caused by poor transducer selection or poor pipe wall conditions, which may result in an incorrectly measured fluid sound velocity. To improve the automatic measurement of Tn, the envelope threshold limit can be adjusted to exclude portions of the envelope, which may be causing the Tn detection problem.

F	0.73
VS	1469.73			Envelope Signal
[ ]	1691:1929		476
D	4:4 4
Tn	55.06 55.06
dT	3.11
S	72	1 91		Envelope Threshold
SN	124:1 3
	TN marker			Crossover Marker
Command Line appears here
	HiSet

If it appears that the default placement of the Tn marker is incorrect or unstable, it can be adjusted by pressing the <5> key on the keypad to invoke the [EnvSet] command (while viewing the envelope screen). A horizontal line representing the envelope threshold level will appear along with a number indicating the percentage level. The High and Low thresholds can then be moved either up or down on the envelope using the <+> or <-> keys. While viewing the Tn marker position, adjust the thresholds so that they are well above the baseline “noise” level but below the first major peak. To exit this mode, press the <0> key.

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