ABB RELION REX640 Technical Manual page 442

Protection functions
ENA_MULT
Figure 253: Functional module diagram
Level detector
The measured residual current is compared to the set
value exceeds the set
timer module. If the ENA_MULT input is active, the
the
The start value multiplication is normally done when the inrush detection function
(INRPHAR) is connected to the ENA_MULT input.
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"
causes an immediate reset. With the reset curve type "Def time reset", the reset
time depends on the
reset", the reset time depends on the current during the drop-off situation and the
value of START_DUR. The START output is deactivated when the reset timer has
elapsed.
442
Io
IRES
BLOCK
Start value , the level detector sends an enable-signal to the
Start value Mult setting.
The protection relay does not accept the
setting if the product of these settings exceeds the
range.
Reset delay time setting. With the reset curve type "Inverse
Timer
Level
detector
t
t
Blocking
logic
Start value setting is multiplied by
Curve parameter A , Curve parameter
Reset delay time value is exceeded.
Type of reset curve setting can be set to
1MRS759142 F
OPERATE
START
Start value . If the measured
Start value or Start value Mult
Start value setting
Operate delay time in the DT
Operating curve
Technical Manual
REX640