ABB 615 series Technical Manual page 558

Section 4
Protection functions
552
Level
I_A
detector
Blocking
BLOCK
logic
Level
I_B
detector
Blocking
BLOCK
logic
Level
I_C
detector
Blocking
BLOCK
logic
GUID-B91E3EF5-7AB5-4F2D-AC6E-5A39FF7BC7B6 V1 EN
Figure 277: Functional module diagram
The module diagram illustrates all the phases of the function. Functionality for phases A,
B and C is identical.
All three phases have independent settings.
Level detector
The module compares differential currents I_A calculated by the peak-to-peak
measurement mode to the set Operate value. The Timer module is activated if the
differential current exceeds the value of the Operate value setting.
Timer
Once activated, Timer activates the PICKUP output. The time characteristic is according
to DT. When the operation timer reaches the value set by Trip delay time, the TRIP output
is activated. If the fault disappears before the module operates, the reset timer is activated.
Timer
PICKUP
t
TRIP
Timer
PICKUP
t
TRIP
Timer
PICKUP
t
TRIP
1MAC059074-MB A
615 series ANSI
Technical Manual