Auto Ct Detection; Mg90V302; Danfoss A/S © 09/2014 All Rights Reserved - Danfoss VLT AAF006 Operating Instructions Manual

Electrical Installation

4.2.8 Auto CT Detection

The active filter performs an auto detection of the installed CT. The CT auto detection can be conducted both while the
system is running and when there is no load. The filter injects a prefixed current of known amplitude and phase angle and
measures the returned CT input. The performance is conducted on each phase individually for several frequencies to check
that phase sequence and RMS are set correctly.
The Auto CT detection is pending on the following conditions:
•
4 4
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:
1000
Table 4.8 Primary Rating [A]
Most restrictions on the CTs come from the installation, such as required cable length, temperature conditions, square
section of conductors, 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 www.deif.com/
Secondary Primary
5 or 1A 30–7500A
5 or 1A 100–5000A
5 or 1A 5 or 1A
Table 4.9 Standard CT Range from Deif: Fits Most Applications
22
Operating Instructions
1250 1500
Accuracy Burden
0.2–0.5-1 1.0–45 V A
0.5–1 1.25–30 V A
0.5–1 15–30 V A
Danfoss A/S © 09/2014 All rights reserved.
2000 2500
Type Description
ASR Measuring current transformer for cables and bus bars
ASK
EASR
EASK
KBU Split core current transformer
KSU/SUSK Summation current transformer
600
3000 3500
750
4000

MG90V302