Siemens HydroRanger 200 Manual de instrucciones descargar pdf (Pagina 233)

7ML19981FC01 HydroRanger 200 – INSTRUCTION MANUAL Page 219

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Appendix C: Troubleshooting

Noise Problems

Incorrect readings can be the result of noise problems, either acoustic or electrical, in the

application.

The noise present at the input to the ultrasonic receiver can be determined by viewing

parameter P807. The display reads ##:##, where the first number is the average noise and

the second is the peak noise. In general, the most useful value is the average noise.

With no transducer attached the noise is under 5 dB. This is often called the noise floor. If

the value with a transducer attached is greater than 5 dB, then signal processing

problems can occur. High noise decreases the maximum distance that can be measured.

The exact relationship between noise and maximum distance is dependent on the

transducer type and the material being measured. Any average noise level greater than

20 dB is probably cause for concern unless the distance is much shorter than the

maximum for the transducer.

Reading fluctuates

while material level is

still (or vice versa).

Incorrect measurement stabi-

lization.

Alter Maximum Process Speed

(P003) or damping (P704)

accordingly. See Maximum Pro-

cess Speed.

Reading is fixed,

regardless of the

actual material level.

Transducer acoustic beam

obstructed, standpipe too

narrow, or transducer ringing

(reads over 100%).

Relocate and / or re-aim trans-

ducer at material level or object.

Proceed to Measurement Diffi-

culties below.

See also: Transducer Ringing.

Material level

reported is always

incorrect by the same

amount.

Incorrect Empty (zero) refer-

ence for level operation

(P001 = 1).

See Empty (P006), Reading Off-

set (P063), Offset Calibration

(P650), & Offset Correction

(P652).

Measurement accu-

racy improves as

level nears trans-

ducer.

Incorrect Sound Velocity used

for distance calculation.

Use a transducer with a built-in

temperature sensor or a TS-3

temperature sensor.

See Sound Velocity.

Reading is erratic,

with little or no rela-

tion to material level.

True echo too weak or wrong

echo being processed.

Relocate and / or re-aim trans-

ducer at material.

Check noise parameters. See

Noise Problems.

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