passed the starting phase, JAMPTOC monitors the magnitude of phase currents.
The function starts when the measured current exceeds the breakdown torque
level, that is, above the set limit. The operation characteristic is definite time.
The function contains a blocking functionality. It is possible to block the function
outputs.
4.1.8.4 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "On" and "Off".
The operation of JAMPTOC can be described with a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 174: Functional module diagram
Level detector
The measured phase currents are compared to the set
Start value
. The TRMS values
of the phase currents are considered for the level detection. The timer module is
enabled if at least two of the measured phase currents exceed the set
Start value
.
Timer
Once activated, the internal START signal is activated. The value is available only
through the Monitored data view. The time characteristic is according to DT. When
the operation timer has reached the
Operate delay time
value, the OPERATE output
is activated.
When the timer has elapsed but the motor stall condition still exists, the OPERATE
output remains active until the phase currents values drop below the
Start value
,
that is, until the stall condition persists. If the drop-off situation occurs while the
operating time is still counting, the reset timer is activated. If the drop-off time
exceeds the set
Reset delay time
, the operating timer is reset.
The timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operating time. The value is
available in the monitored data view.
Blocking logic
There are three operation modes in the blocking function. The operation modes
are controlled by the BLOCK input and the global setting in Configuration >
System > Blocking mode which selects the blocking mode. The BLOCK input can be
controlled by a binary input, a horizontal communication input or an internal signal
of the protection relay's program. The influence of the BLOCK signal activation is
preselected with the global setting
Blocking mode
.
Protection functions
1MRS757644 H
352 620 series
Technical Manual
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