• threshold comparator
• block signal check
• time delay characteristics
• output processing.
The inputs for the function are the following:
• operating mode selections
• setting parameters
• digital inputs and logic signals
• measured and pre-processed current magnitudes.
The function's outputs are START, TRIP and BLOCKED signals which can be used for direct I/O
controlling and user logic programming. The function generates general time-stamped ON/OFF events
to the common event buffer from each of the three (3) output signals. In instant operating mode the
function outputs START and TRIP events simultaneously with an equivalent time stamp. The time stamp
resolution is 1 ms. The function also provides a resettable cumulative counter for the START, TRIP and
BLOCKED events.
The following figure presents a simplified function block diagram of the current unbalance function.
Figure. 5.4.6 - 42. Simplified function block diagram of the I2> function.
Measured input
The function block uses analog current measurement values and always uses calculated positive and
negative sequence currents. In the broken conductor mode (I2/I1) the function also uses the RMS
values of all phase currents to check the minimum current. Zero sequence and component sequence
angles are used for fault registering and for fault analysis processing. A -20 ms averaged value of the
selected magnitude is used for pre-fault data registering.
Table. 5.4.6 - 78. Measurement inputs of the I2> function.
Signal
Description
Time base
I1
Positive sequence current magnitude
5 ms
I2
Negative sequence current magnitude
5 ms
IZ
Zero sequence current magnitude
5 ms
I1 ANG
Positive sequence current angle
5 ms
I2 ANG
Negative sequence current angle
5 ms
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
© Arcteq Relays Ltd
IM00021
97
Summary of Contents for AQ-M257
Page 1: ...AQ M257 Motor protection IED Instruction manual...
Page 2: ......
