
PQS1
PQS>/<
32
Power protection
FRQV1
f>
f>>
f>>>
f>>>>
f<
f<<
f<<<
f<<<<
81O/81U
Frequency protection (8 stages)
ROCOF1 df/dt
81R
Rate-of-change of frequency protection (8 stages)
PGS1
PGx >/<
99
Programmable stage
ARC1
IArc>/I0Arc>
50Arc/50NArc
Arc protection (Option)
Table. 5.1. - 2. Control functions of AQ-T257
Name
IEC
ANSI
Description
SG
-
-
Set group settings
OBJ
-
-
Object control
SYN
ΔV/Δa/Δf
25
Synchrocheck
VRG
-
-
Voltage regulator (Function package)
Table. 5.1. - 3. Monitoring functions of AQ-T257
Name
IEC
ANSI
Description
CTS
-
-
Current transformer supervision
VTS
-
60
Fuse failure
DR
-
-
Disturbance recorder
MR
-
-
Measurement recorder
CBW
-
-
Circuit breaker wear monitor
THD
-
-
Total harmonic distortion
VREC
-
-
Measurement value recorder
5.2. Measurements
5.2.1. Current measurement and scaling in differential application
Current measurement module (CT-module) is used for measuring the currents from current
transformers and processing the measured currents to measurement database and for use of
measurement- and protection functions. For the measurements to be correct it is essential to
understand the concept of current measurements.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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