ABB ETL600 Instruction Manual page 214

ABB Switzerland Ltd
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 coupling filter
BT balancing transformer
Fig. 7-7
CF coupling filter
BT balancing transformer
Fig. 7-8
7-8
1KHW001489-EN
Line attenuation
Phase-to-ground
CF
R0
V0
a = 20 log
tot
Test circuit for measuring line attenuation in the case
of single-phase coupling
CF CF
BT
R0
V0
a = 20 log
Test circuit for measuring line attenuation in the case
of phase-to-phase coupling
November 2005
CF
V1
R1
V0 R1
( )
+ 10 log
2V1 R0
CF CF
BT
V1
R1
V0
2V1
ETL600
Commissioning