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:
•
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:
600 750
1000 1250 1500 2000 2500 3000 3500 4000
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 Accuracy Burden Type Description
5 or 1A 30–7500A 0.2–0.5-1 1.0–45 V A ASR
ASK
EASR
EASK
Measuring current transformer for cables and bus bars
5 or 1A 100–5000A 0.5–1 1.25–30 V A KBU Split core current transformer
5 or 1A 5 or 1A 0.5–1 15–30 V A KSU/SUSK Summation current transformer
Table 4.9 Standard CT Range from Deif: Fits Most Applications
Electrical Installation Operating Instructions
22 Danfoss A/S © 09/2014 All rights reserved. MG90V302
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