ABB RELION 620 Series Technical Manual page 341

1MRS757644 F
620 series
Technical Manual
GUID-93025A7F-12BE-4ACD-8BD3-C144CB73F65A V2 EN
Figure 164: 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 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.
The Blocking mode setting has three blocking methods. In the "Freeze timers" mode,
the operation timer is frozen to the prevailing value. In the "Block all" mode, the whole
function is blocked and the timers are reset. In the "Block OPERATE output" mode,
the function operates normally but the OPERATE output is not activated.
Section 4
Protection functions
335