VEGA Capacitive electrodes EK … with signal conditioning instrument - Manual (Page 32)

32 Capacitive electrodes EK with signal conditioning instrument
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mA 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 - short-circuit on the input
conditioning instru- - sensor not correctly connected
ment lights - sensor line interrupted
- 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, trigger a fault signal on the signal conditioning instru-
ments.
Measure the current on the connection line to the sensor.
The terminal voltage of the sensor in standard condition is at least 12 V.
Note with Ex-systems that the Ex-protection is not influenced
by the measuring instruments.
a. Current value < 2 mA
- Check the supply voltage on the connection line to the sensor. The
voltage should be approx. 17 … 24 V.
Should you measure a value below 17 V, the signal conditioning in-
strument is defect. In this case send the instrument to VEGA for
repair.
- Should the red failure lamp continue to light, separate the connection
line from the signal conditioning instrument and connect a resistor of
2,2 kOhm to the sensor inputs of the signal conditioning instrument.
Should the failure lamp continue to light, the signal conditioning instru-
ment is defect. In this case return the instrument to VEGA for repair.
- Should the failure lamp extinguish, connect the signal conditioning
instrument again. Separate the sensor from the connection line and
connect instead a resistor of 2,2 kOhm.
- Should the failure lamp continue to light, perhaps 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.
Signal conditioning
instrument e.g.
VEGATOR
4 … 20 mA 12 … 24 V