ABB 615 series Technical Manual page 269

1MAC059074-MB A
615 series ANSI
Technical Manual
Do not set the multiplier Pickup value Mult setting higher than necessary.
If the value is too high, the function may not trip at all during an inrush
followed by a fault, no matter how severe the fault is.
The pickup value multiplication is normally done when the inrush detection function INR
is connected to the ENA_MULT input.
Phase selection logic
If the fault criteria are fulfilled in the level detector, the phase selection logic detects the
phase or phases in which the measured current exceeds the setting. If the phase
information matches the Num of pickup phases setting, the phase selection logic activates
the Timer module.
Timer
Once activated, the Timer module 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 settings Curve parameter A, Curve parameter B, Curve parameter C,
Curve parameter D and Curve parameter E.
In a drop-off situation, that is, when 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 Time multiplier is used for scaling the IDMT trip and reset times.
Section 4
Protection functions
263