Figure 187: Functional module diagram
Level detector
The operating quantity can be selected with the setting
Io signal Sel
. The selectable
options are "Measured Io" and "Calculated Io". The operating quantity 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. The
START output is deactivated when the reset timer has elapsed.
The "Inverse reset" selection is only supported with ANSI or user
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 operate and reset times.
1MRS757644 H
Protection functions
620 series
Technical Manual
377
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