ABB 615 Series ANSI, Technical Manual

Page: 162 / 713

1MAC050144-MB C
Section 4
Protection functions
615 series ANSI 155
Technical Manual
The pickup value multiplication is normally done when the inrush detection function
(INR) is connected to the
ENA_MULT
input.
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 operate 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. If the
drop-off situation continues, the reset timer is reset and the
PICKUP
output is deactivated.
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 timer calculates the pickup duration (PICKUP_DUR) value which indicates the
percentual ratio of the pickup situation and the set trip time. The value is available through
the Monitored data view.
Do not set the multiplier setting Pickup value Mult 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 "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 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 operate time setting. For more information, see the
General function block features section in this manual