ABB RELION Series Technical Manual page 408

Section 4
Protection functions
402
The operation of PDNSPTOC can be described by using a module diagram. All the
modules in the diagram are explained in the next sections.
A070687 V2 EN
Figure 208: Functional module diagram
I /I
2 1
The I /I module calculates the ratio of the negative and positive sequence current. It
2 1
reports the calculated value to the level detector.
Level detector
The level detector compares the calculated ratio of the negative and positive-sequence
currents to the set Start value. If the calculated value exceeds the set Start value and
the min current check module has exceeded the value of Min phase current, the level
detector reports the exceeding of the value to the timer.
Min current check
The min current check module checks whether the measured phase currents are above
the set Min phase current. At least one of the phase currents needs to be above the set
limit to enable the level detector module.
Timer
Once activated, the timer activates the START output. The time characteristic is
according to DT. When the operation timer has reached the value set by Operate delay
time, the OPERATE output is activated. If the fault disappears before the module
operates, the reset timer is activated. If the reset timer reaches the value set by Reset
delay time, the operate timer resets and the START output is deactivated.
The timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operation 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
1MRS758755 A
REC615 and RER615
Technical Manual