ABB 615 series Technical Manual page 322

Section 4
Protection functions
316
Timer
Once activated, the timer activates the PICKUP 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 Trip delay time in the DT mode or the
maximum value defined by the inverse time curve, the TRIP output is activated.
When the user-programmable IDMT curve is selected, the operation time characteristics
are defined by the parameters Curve parameter A, Curve parameter 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 trip delay is
exceeded, the timer reset state is activated. The functionality of the timer in the reset state
depends on the combination of the Operating curve type, Type of reset curve and Reset
delay time settings. When the DT characteristic is selected, the reset timer runs until the set
Reset delay time value is exceeded. When the IDMT curves are selected, the Type of reset
curve setting can be set to "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 delay time setting. With the reset curve type
"Inverse reset", the reset time depends on the current during the drop-off situation. The
PICKUP output is deactivated when the reset timer has elapsed.
The "Inverse reset" selection is only supported with ANSI or user
programmable types of the IDMT operating curves. If another operating
curve type is selected, an immediate reset occurs during the drop-off
situation.
The setting Time multiplier is used for scaling the IDMT trip and reset times.
The setting parameter Minimum trip time defines the minimum desired trip time for
IDMT. The setting is applicable only when the IDMT curves are used.
The Minimum trip time setting should be used with great care because the
operation time is according to the IDMT curve, but always at least the
value of the Minimum trip time setting. For more information, see the
IDMT curves for overcurrent protection
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.
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
1MAC059074-MB A
section in this manual.
615 series ANSI
Technical Manual