Summation Transformers - Danfoss VLT AAF00x Instruction Manual

How to Install
- Active Filter bigger than 10% of CT RMS rate
- CTs installed on source (PCC) side (auto CT not
possible for load side CT installation)
- Only one CT per phase (not possible for
summation CTs)
- CTs are part of below standard range:
4 4
1000 1250
Table 4.6 Primary Rating [A]
Most restrictions on the current transformers comes from
the installation, such as necessary cable length,
temperature conditions, square section of conducts,
standard or split core layout, etc. A broad range of
different current transformers can be used independently
of brand and type.
For specific CT requirements contact the local supplier or
go to
http://www.deif.com/Download_Centre/Search.aspx?search-
string=dct:
Secondary Primary
5 or 1A 30–
7500A
5 or 1A 100–
5000A
5 or 1A 5 or 1A
Table 4.7 Standard CT Range from Deif - Fits Most Applications

4.5.9 Summation Transformers

Multiple current sources:
If the filter is to compensate current from several sources,
summation CTs need to be installed. This is often the case
if the filter is installed in systems with a generator backup
or where the filter is only to compensate a limited number
of loads.
4-26
VLT Active Filter AAF 00x
1500 2000 2500 3000
Accuracy Burden Type
0.2–0.5-1 1.0–45V ASR
A ASK
EASR
EASK
0.5–1 1.25–30V KBU
A
0.5–1 15–30V KSU/
A SUSK
MG.90.V2.22 - VLT
G
600 750
3500 4000
PCC1
Figure 4.34 Summation CTs on generator backup applications
(PCC-side). Filter compensates full current of transformer and
generator.
Description
Measuring
current
transformer
for cables and
bus bars
Split core
current
transformer
Summation
current
transformer
PCC1
M
Figure 4.35 Summation CTs example for individual harmonic
compensation (load side).
®
is a registered Danfoss trademark
M M M
M
AAF
AAF
M