AUX E&H Series Instruções de Operação descarregar pdf (Página 78)

8.6.5 Connecting lines and junction boxes

Check cables and connections for moisture.

Moisture reduces the sensor slope. If the

display can not be called up or is fixed on

pH 7, please check the following components:

• Sensor head

• Sensor plug

• pH measuring cable

• Junction box if present

• Extension cable

Note:

The sensor head and junction box

can be cleaned and dried with a

hair-drier.

Caution:

If moisture is found on the

measuring cable, the cable

absolutely must be replaced.

A shunt in the cable of > 20 MΩ cannot be

measured with normal multimeters, but is very

detrimental to pH measurement. Reliable

testing is possible with a commercially

available insulation resistance meter:

• Disconnect the pH measuring cable from

the sensor and instrument.

• If a junction box is used, the incoming and

outgoing pH cables should be checked

separately.

• Preferably test the cable with a test voltage

of 1000 V DC (but least with 500 V DC) test.

• Insulation resistance of an intact cable is

> 100 GΩ.

• Defective (moist) cables will cause

flashover.

Cable replacement is mandatory!

Diagnosis and corrective maintenance Liquisys M CPM 223 / 253

76 Endress+Hauser

1 2 ... 73 74 75 76 77 78 79 80 81 82 83 ... 91 92

Sem comentários

AUX E&H Series Instruções de Operação Página 78