Nm/in-lbs
13
0B
B7
41
.1
0
Figure 4.28 Tightening Bolts with Torque Wrench
NOTE!
Always use a torque wrench to tighten the bolts.
4.5.6 Shielded Cables
It is important that shielded cables are connected properly
to ensure high EMC immunity and low emissions.
Connection can be made using either cable connectors or
clamps:
•
EMC cable connectors: generally available cable
connectors can be used to ensure an optimum
EMC connection.
•
EMC cable clamp: Clamps allowing easy
connection are supplied with the unit.
4.5.7 Current Transformer (CT)
The filter operates in closed-loop operation by receiving
current signals for external current transformers. The
received signal is processed and the filter reacts according
to programmed actions.
CAUTION
Incorrect current transformer connection, installation or
configuration will lead to unintended and uncontrollable
behavior of the filter.
NOTE!
The current transformers are not part of the filter package
and must be purchased separately.
Current transformer specification
The active filter supports most current transformers. The
current transformers must have the following specifi-
cations:
Technical specification of active filter passive current
transformers:
RMS
maximum measured RMS current
Accuracy
0.5% or better (Class 0.5)
Rated current
1A or 5A (5A is recommended)
Set-up via hardware
Rated frequency
50/60 Hz
Rated power/burden
See
(AAF’s burden equal 2m
Ω
)
Rated power/
burden [VA]
5
7.5
10
15
30
Impedance of
current CT [
Ω
]
≤ 0.15
≤ 0.25
≤ 0.35
≤ 0.55
≤ 1.15
Table 4.4 Rated Power/Burden
NOTE!
All other technical data like dynamic rated current,
maximal permitted operating voltage, thermal
dimensioning of continuous current, thermal dimensioning
of short-time current, overcurrent limit, isolation class,
working temperature range, etc. are specific values of the
system and must be defined during the project planning
phase of the equipment.
RMS Specification
The minimum RMS has to be determined by the total
current that passes through the current transformer. It is
important that the current sensor is not too small, which
would lead to sensor saturation. Add 10% margin and pick
the next larger standard RMS rate. It is advised to use
current transformers with an RMS rating close to the
maximum current that flows through it to allow the
highest possible accuracy of the measurement and, as a
result, ideal compensation.
CT Burden
In order to ensure that the current transformer performs
according to specifications, the rated burden should not
be above the true current requirement by the active filter.
The burden of the CT depends on the wire type and the
cable length between the CT and the filter CT connection
terminal. The filter itself contributes with 2m
Ω
.
How to Install
VLT Active Filter AAF 00x
4-22
MG.90.V2.22 - VLT
®
is a registered Danfoss trademark
4
4
