71
TN4FCXA2
j
-EDF-
E
Maintenance
Checking the surge protector:
Measure the output current of the transmitter on the 4/20mA loop on the one hand, and between
terminals CK+ and CK- on the other hand.
If the measured values are the same, the surge protector is in good condition.
If the measured values differ by more than 0.1% (0.016mA), the surge protector is defective.
The whole terminal block must then be replaced.
Do not perform a dielectric test on of transmitters equipped with a surge protector. The test
equipment generates high voltages which would damage the surge protector.
If an insulation test is done, use a low voltage ohmmeter (27 Vdc max) with an internal insulation
resistance of 12
Ω
max.
Current output on the 4/20 mA loop:
Disconnect the wire from the loop of the “-” of the terminal, connect one end of the test resistance
to the previous wire and the other end to the “-” terminal
Output current between terminals CK+ and CK-:
Digital voltmeter
To CK -
To CK +
Precision resistance
(1 or 10
Ω
)
Résistance de précision
Vers borne (+)
borne (+)
borne (–)
Vers borne (–)
Tension
d'alimentation
en CC
Voltmètre numérique
