Electrode Cable; Protective Wiring Of Switching Contacts - Hach LANGE si628 P Manuel D'utilisateur

3. Installation

3.3. Electrode cable

Coaxial cable
Installation of BNC connector to the cable
The instrument is supplied with a BNC connector, to be screwed directly (without weldings) to the coaxial
cable. To assemble it, the cable must be prepared and the connector screwed (see diagram below).
5 mm
Ø
0.2 in
Coaxial cable
Using a triaxial cable the connector is assemblied in the same way as with the coaxial cable, leaving the
"additional" shielding and the outer protector out of the connector. The additional shielding must be con-
nected to ground.

3.4. Protective wiring of switching contacts

Relay contacts are subjected to electrical erosion.
Especially with inductive and capacitive loads, the service life of the contacts will be reduced.
For suppression of sparks and arcing, components such as RC combinations, nonlinear resistors, series
resistors and diodes should be used.
Typical protective wirings
AC applications with inductive load
Load
Contact
relay
Typical RC at 230 VAC: Capacitor 0.1 µF/630 V
Maximum relays load: AC < 24 V / < 3 A / < 72 VA.
si628 P_HACH_LANGE_Ed.0510.indd ANG:13 si628 P_HACH_LANGE_Ed.0510.indd ANG:13
PVC protector Ø 5 mm.
Shielding
Plastic conductor (black).
PE insulation.
Inner conductor.
7 mm
0.3 in
Cable preparation
RC
RC
Resistor 100 Ω/1 W
Triaxial cable
7 mm
0.3 in
Cable with connector already screwed
DC applications with
inductive load
Diode
1N4007
PVC protector Ø 7 mm.
Additional shielding.
(See Important notes
pages 9 and 12).
AC/DC with
capacitive load
Load
R
R, for example:
5 Ω / 1 W at
24 V / 0.4 A
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