CYG PRS-7367 - Protection Principle

Protection Functions
PRS-7367 93
Signal
Description
U3P
The voltage in all the three phases
Blk
This signal blocks all the binary output signals of the function
Blk_Str
This signal blocks all the start outputs of the function
Blk_Op
This signal blocks all the trip signals of the function.
Table 3.14-2 Output Signals
Signal
Description
Str
This is the integrated start signal
Op
This is the integrated operation signal.
3.14.2 59N Protection Principle
The negative-sequence overvoltage protection function can be enabled or disabled by setting the
corresponding 59N_Ena parameter values as "1" or "0".
The operation of the negative-sequence overvoltage protection can be described using a module
diagram. All the modules in the diagram are explained in the next sections.
The functional module diagram is shown as below:
&
U2>59N_Vol_Str
ANA
SIG
59N_Op
SIG
59N_Str
SIG
59N_Blk=1
&
&
SIG
59N_Blk_Str=1
59N_Ena=1
SET
SIG
59N_Blk_Op=1
30ms
59N_Op_T
Figure 3.14-2 Functional module diagram
The calculated negative-sequence voltage is compared to the set 59N_Vol_Str setting. If the value
exceeds the set 59N_Vol_Str and no block signal is activated, the timer and 59N_Str signal are
activated.
Where:
59N_Vol_Str is the start value for the voltage.
59N_Op_T is operating delay time for 59N.
The time characteristic is according to DT. When the operation timer has reached the value set by
59N_Op_T, the OPERATE output is activated if the overvoltage condition persists. If the
negative-sequence voltage normalizes before the module operates, the operation will reset with a
time delay of 30ms.
The binary input 59N_Blk can be used to block the function. The activation of the BLOCK input
deactivates all outputs and resets internal timers. The binary input 59N_Blk_Str can be used to
block the start signals. The binary input 59N_Blk_Op can be used to block the operation signals.