ABB RELION REX640 Technical Manual page 821

1MRS759142 F
The operation of NSPTOC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
ENA_MULT
Figure 466: Functional module diagram
Level detector
The measured negative-sequence current is compared to the set
the measured value exceeds the set
module. If the ENA_MULT input is active, the set
Start value Mult .
Timer
Once activated, Timer activates the START output. Depending on the value of the
Operating curve type setting, the time characteristics are according to DT or IDMT.
When the operation timer has reached the value of Operate delay time in the DT
mode or the maximum value defined by the inverse time curve, the OPERATE output
is activated.
When the user-programmable IDMT curve is selected, the operation time
characteristics are defined by the parameters
B , Curve parameter C , Curve parameter D and Curve parameter E .
If a drop-off situation happens, that is, a fault suddenly disappears before the
operate delay is exceeded, the timer reset state is activated. The functionality of
the timer in the reset state depends on the combination of the
type , Type of reset curve and Reset delay time settings. When the DT characteristic
is selected, the reset timer runs until the set
When the IDMT curves are selected, the
"Immediate", "Def time reset" or "Inverse reset". The reset curve type "Immediate"
causes an immediate reset. With the reset curve type "Def time reset", the reset
time depends on the
reset", the reset time depends on the current during the drop-off situation. The
START output is deactivated when the reset timer has elapsed.
If a drop-off situation happens, that is, a fault suddenly disappears before the
operate delay is exceeded, the timer reset state is activated. The functionality of
the timer in the reset state depends on the combination of the
type , Type of reset curve and Reset delay time settings. When the DT characteristic
REX640
Technical Manual
I
2
I3P
BLOCK
The protection relay does not accept the
setting if the product of the settings exceeds the
range.
Reset delay time setting. With the reset curve type "Inverse
Timer
Level
detector
t
t
Blocking
logic
Start value , Level detector activates the Timer
Start value is multiplied by the set
Curve parameter A , Curve parameter
Reset delay time value is exceeded.
Type of reset curve setting can be set to
Protection functions
OPERATE
START
Start value . If
Start value or Start value Mult
Start value setting
Operating curve
Operating curve
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