HT instruments HT5000 - Manual (Page 9)

HT-5000
EN - 8
4.2.2 Options for direct and inductive signal coupling
CAUTION
If the transmitter is connected to electrical service cables, it has to be
considered that the device is designed to achieve CAT II / CAT III 440 V and
CAT IV 300 V with Class 2 protection (double insulation) according to IEC / EN
61010-1. This means that the maximum voltage between the two terminals
must not exceed 440 V in measurement categories CAT II / CAT III and 300 V
in measurement category CAT IV
4.2.2.1 Direct coupling on cables and pipes
Direct galvanic coupling is practical for cables which are easily accessible and free of
current. The method of connection is dependent upon the position and nature of the lines
(e.g. insulation, cable conduit, accessibility of the cable ends).
Direct coupling presents a reliable option for selective cable location, as the signal can be
coupled onto a specific cable with virtually no loss.
The following illustration shows an example of direct coupling:
Fig. 4: Direct coupling on cables and pipes
CAUTION
If the lines being located are energised, the following five safety precautions
should be taken before connecting the transmitter:
1. Disconnect power supply
2. Secure against reconnection
3. Check for presence of current
4. Make earth connection and short circuit of parts
5. Cover or block access to adjacent components which are energized
If the system cannot be de-energized the use of the inductive coupling
clamp is possible to perform the location of objects
The following table explains various basic principles of direct galvanic coupling.