ABB RED615 Technical Manual page 168

Section 4
Protection functions
162
Once activated, the timer activates the START 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 Operate delay time in
the DT mode or the maximum value defined by the inverse time curve, the
OPERATE output is activated.
When the programmable IDMT curve is selected, the operating time characteristics
are defined with the parameters Curve parameter A, Curve parameter B, Curve
parameter C, Curve parameter D and Curve parameter E.
The shortest IDMT operation time is adjustable. It can be set up
with the global parameter in the HMI menu: Configuration/System/
IDMT Sat point. More information can be found in the
function block features
If a drop-off situation happens, that is, a fault suddenly disappears before the
operate 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
START output is deactivated when the reset timer has elapsed.
The "Inverse reset" selection is only supported with ANSI or
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 operation and reset times.
The setting parameter Minimum operate time defines the minimum desired
operation time for IDMT. The setting is applicable only when the IDMT curves are
used.
The Minimum operate 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. More
information can be found in the
section in this manual.
section.
General function block features
1YHT530004D05 D
General
615 series
Technical Manual