ABB RELION 620 Series Technical Manual page 295

1MRS757644 F
620 series
Technical Manual
Each phase has its own phase-specific starting and operating outputs: ST_A, ST_B,
ST_C, OPR_A, OPR_B and OPR_C.
Once activated, each timer activates its 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 operation time characteristics
are defined by 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. The setup can be
done with a global parameter in the HMI menu: Configuration/
System/IDMT Sat point. More information can be found in the
General function block features
If a drop-off situation happens, that is, a fault suddenly disappears before the operation
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 START output is deactivated.
The "Inverse reset" selection is only supported with ANSI or
programmable IDMT operating curves. If another operating curve
type is selected, an immediate reset occurs during the drop-off
situation.
The Time multiplier setting is used for scaling the IDMT operating and reset times.
The setting parameter Minimum operate time defines the minimum desired operating
time for IDMT. The setting is applicable only when the IDMT curves are used.
The Minimum operate timeoperating setting should be used with
great care because the operation time is according to the IDMT
operating curve, but always at least the value of the Minimum operate
time setting. More information can be found in the
block features
section in this manual.
section in this manual.
Section 4
Protection functions
General function
289