ABB 615 Series - Application

PICKUP
TRIP
Level
detector 1
BLOCK
I_A
Timer
t
Level
detector 2
I_B
I_C
GUID-4A6308B8-47E8-498D-A268-1386EBBBEC8F-ANSI V1 EN
Figure 138: Functional module diagram
Level detector 1
This module compares the phase currents (RMS value) to the set Pickup value high
setting. If all the phase current values are less than the set Pickup value high value, the loss
of load condition is detected and an enable signal is sent to the timer. This signal is
disabled after one or several phase currents have exceeded the set Pickup value high value
of the element.
Level detector 2
This is a low-current detection module, which monitors the de-energized condition of the
motor. It compares the phase currents (RMS value) to the set Pickup value low setting. If
any of the phase current values is less than the set Pickup value low, a signal is sent to block
the operation of the timer.
Timer
Once activated, the timer activates the PICKUP output. The time characteristic is
according to DT. When the operation timer has reached the value set by Trip delay time,
the TRIP output is activated. If the fault disappears before the module trips, the reset timer
is activated. If the reset timer reaches the value set by Reset delay time, the operation timer
resets and the PICKUP output is deactivated.
The timer calculates the pickup duration value PICKUP_DUR, which indicates the
percentage ratio of the pickup situation and the set trip time. The value is available in the
monitored data view.
The BLOCK signal blocks the operation of the function and resets the timer.
4.1.7.5 Application
When a motor runs with a load connected, it draws a current equal to a value between the
no-load value and the rated current of the motor. The minimum load current can be
determined by studying the characteristics of the connected load. When the current drawn
by the motor is less than the minimum load current drawn, it can be inferred that the motor
Section 4 1MAC059074-MB A
Protection functions
290 615 series ANSI
Technical Manual