Level
detector
IRES
BLOCK
ENA_MULT
t
Timer
t
OPERATE
START
Io
Blocking
logic
Figure 253: Functional module diagram
Level detector
The measured residual current is compared to the set
Start value. If the measured
value exceeds the set
Start value, the level detector sends an enable-signal to the
timer module. If the
ENA_MULT
input is active, the
Start value setting is multiplied by
the
Start value Mult setting.
The protection relay does not accept the
Start value or Start value Mult
setting if the product of these settings exceeds the
Start value setting
range.
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
Operate delay time in the DT
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
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
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 and the
value of START_DUR. The
START
output is deactivated when the reset timer has
elapsed.
Protection functions
1MRS759142 F
442
REX640
Technical Manual