ABB ETL600 Instruction Manual page 211

ETL600
Appreciable discrepancies between the measured results and the
nominal characteristic point to defective components and the filters
must be checked individually.
SELECTIVE LEVEL
METER SPM 32/33
impedance
appr. 5 kOhm
Output
impedance
approx. 10 Ohm
GENERATOR PS 33
Instruments:
1. Signal generator
2. Selective level meter
Fig. 7-1
Phase-to-ground
CF
BT
Z0
Z
Fig. 7-2
Commissioning
1KHW001489-EN
Input
Rec.
Gen.
measuring bridge
Instruments and test circuit for measuring return loss
CF
R e t u r n
lo s s
a
r
coupling filter
balancing transformer
nominal impedance
actual input impedance
Test circuit for measuring return loss under practical
conditions with the transmission line as load
R
N
R
X
Return loss
e.g.:
Acterna PS 33
Acterna SPM 32/33
Phase-to-phase or between line circuits
Z0 + Z
a = 20 log
r
Z0 - Z
November 2005
ABB Switzerland Ltd
Dummy load
Nominal output
impedance:
e.g. 75 Ohm
Coaxial cable
to coupling unit
CF CF
BT
R e tu rn
lo s s
a
r
7-5