ABB PQFM Instruction Manual page 63

6.10.4 CT locations for the case of global compensation – transformer busbar
not accessible
The active filter is required to filter the loads of side A and side B (Cf.
transformer busbar is not accessible. As a result, the CTs cannot be installed in a central
position.
Figure 41: Case of multiple loads and transformer busbar not accessible
For this configuration, three CTs (one per phase) have to be installed on side A and on
side B (i.e. in total 6 CTs). Those CTs will then feed 3 summation CTs (one per phase) that
are connected to the active filter. This CT topology is represented in
CT 1 (one per phase)
Primary: X
Secondary: 5A
Figure 42: CT connections for the case of multiple loads and transformer busbar not accessible
The CTs installed in each phase of side A and B (CT1 and CT2) must be identical (X/5A)
and feed a summation CT whose secondary is 5A (5+5/5A). The summation CT is then
connected to the active filter in accordance with
CTs (one per phase) must be used.
LOADS
(Side A)
CT 2 (one per phase)
Primary: X
Secondary: 5A
LOADS
LOADS
(Side A) (Side B)
(to be done for each phase)
Manual Power Quality Filter PQFM ç Electrical design and installation 63
LOADS
PQF
(Side B)
PQF
Section 6.10.1.
Figure 41) but the
Figure 41.
Summation CT
(one per phase)
Primary 1: 5 A
Primary 2: 5A
Secondary: 5A
A total of 3 summation