ABB RELION REX640 Technical Manual page 328

Protection functions
The start value multiplication is normally done when the inrush detection function
(INRPHAR) is connected to the ENA_MULT input.
Figure 199: Start value behavior with ENA_MULT input activated
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
activates the timer module.
Timer
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
mode or the maximum value defined by the inverse time curve, the OPERATE output
is activated.
When the user-programmable IDMT curve is selected, the operation time
characteristics are defined by the parameters
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
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
type , Type of reset curve and Reset delay time settings. When the DT characteristic
is selected, the reset timer runs until the set
When the IDMT curves are selected, the
"Immediate", "Def time reset" or "Inverse reset". The reset curve type "Immediate"
328
Num of start phases setting, the phase selection logic
Curve parameter A , Curve parameter
Reset delay time value is exceeded.
Type of reset curve setting can be set to
1MRS759142 F
Operate delay time in the DT
Operating curve
Technical Manual
REX640