VEGA Capacitive electrodes EL … - Manual (Page 40)

40 Capacitive electrodes EL …
28
30
32
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–
+
–
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mA V
4 … 20 mA 12 … 20 V
Sensor
Diagnosis
5.4 Failure removal
Failure Measure, failure removal
The red failure Check the sensor inputs on the following failures:
LED of the signal - Sensor not connected correctly
conditioning instru- - Sensor line interrupted
ment lights - Supply voltage too low
Check if the sensor is connected correctly.
- Failures on the sensor, effecting a current change below 2 mA or above
23 mA lead to a fault signal on the signal conditioning instrument.
Measure the current on the connection line to the sensor.
The terminal voltage on the sensor in standard condition is at least 12 V.
Note with Ex-systems, that the Ex-protection is not influenced by
the meas. instruments.
a. Current value < 2 mA
- Check the supply voltage on the connection line to the sensor. The
voltage should be approx. 18 … 24 V.
Should you measure a value below 18 V, this means a defect in the
signal conditioning instrument. In this case return the instrument for
repair to VEGA.
- Should the red failure lamp still light, separate the connection line from
the signal conditioning instrument and connect a resistor of 1 k Ω to the
sensor inputs of the signal conditioning instrument.
When the failure lamp continues to light, the signal conditioning
instrument is defect. In this case return the instrument for repair to
VEGA.
- When the failure lamp extinguishes, connect the signal conditioning
instrument again. Separate the sensor from the connection line and
connect a resistor of 1 k
Ω .
- When the failure lamp still lights, probably the connection line is
interrupted. Check the connection line to the sensor.
- When the failure lamp extinguishes, the sensor is defect. Check the
connected sensor.
e.g. VEGATOR