ABB ETL600 - Page 214

ABB Switzerland Ltd 1KHW001489-EN ETL600
grounded behind the line traps. The test circuit is shown in Fig. 7-7
and Fig. 7-8.
Unexpectedly high attenuation or fluctuations of attenuation of several
dB's within just a few kHz would indicate a defective line trap or
extremely unusual characteristics of the line itself. It is essential that
the cause is found and corrected before the PLC equipment is finally
commissioned.
CF CF
R0
V0
V1
R1
Line attenuation
Phase-to-ground
a = 20 log
V0
2V1
+ 10 log
R1
R0
()
tot
CF
BT
coupling filter
balancing transformer
Fig. 7-7 Test circuit for measuring line attenuation in the case
of single-phase coupling
CF CF
BT
CFCF
BT
R0
V0
V1
R1
a = 20 log
V0
2V1
CF
BT
coupling filter
balancing transformer
Fig. 7-8 Test circuit for measuring line attenuation in the case
of phase-to-phase coupling
7-8 November 2005 Commissioning