The blocking of the function causes an HMI display event and a time-stamped blocking event with
information of the startup current values and its fault type to be issued.
The blocking signal can also be tested in the commissioning phase by a software switch signal when
the relay's testing mode "Enable stage forcing" is activated (
General
→
Device).
The variables the user can set are binary signals from the system. The blocking signal needs to reach
the device minimum of 5 ms before the set operating delay has passed in order for the blocking to
activate in time.
Events and registers
The undercurrent function (abbreviated "NUC" in event block names) generates events and registers
from the status changes in START, TRIP and BLOCKED. The user can select which event messages
are stored in the main event buffer: ON, OFF, or both.
The events triggered by the function are recorded with a time stamp and with process data values.
Table. 5.4.20 - 175. Event messages.
Event block name
Event names
NUC1
Start ON
NUC1
Start OFF
NUC1
Trip ON
NUC1
Trip OFF
NUC1
Block ON
NUC1
Block OFF
The function registers its operation into the last twelve (12) time-stamped registers. The register of the
function records the ON event process data for START, TRIP or BLOCKED. The table below
presents the structure of the function's register content.
Table. 5.4.20 - 176. Register content.
Date and time Event
Fault type
Pre-trigger
current
Fault
current
Prefault
current
Trip time
remaining
Used SG
dd.mm.yyyy
hh:mm:ss.mss
Event
name
L1-G…L1-L2-L3
Start/
Trip -20ms
current
Start/Trip
current
Start
-200ms
current
0 ms...1800s
Setting group
1...8 active
5.4.21 Mechanical jam protection (Im>; 51M)
The mechanical jam protection function is used for monitoring motor loading after motor starting. When
a motor-run apparatus jams during its work load, this function can be used to disconnect the motor
from the feeding network in order to avoid further damage to the motor drive. The function is active
only after the motor has started, and it is blocked during motor starting. This is done through
an internal connection of
Motor running and through a Motor starting signal taken from the Motor
status monitoring function. This function operates similarly to the motor starting/locked rotor function
(Ist>; 48/14) although it operates on Definite Time delay and does not work during motor starting. Also,
with the help of a dedicated locked rotor function and mechanical jam protection the user can divide all
possible fault situations based on a quick definition of the fault types in relay events. Additionally, the
Ist> function's setup can be problematic with heavy inertia loads that experience a locked rotor
situation during work load. Having separate functions for start-up and for mechanical jams divides the
situations clearly; for example, the mechanical jam protection can be set to instant operation while the
locked rotor function allows motor starting several tens of seconds.
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
210
© Arcteq Relays Ltd
IM00021
Summary of Contents for AQ-M257
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