The
Characteristic angle
setting is used in the "Phase angle" mode to adjust the
operation according to the method of neutral point earthing so that in an isolated
network the
Characteristic angle
(φ
RCA
) = -90° and in a compensated network φ
RCA
= 0°. In addition, the characteristic angle can be changed via the control signal
RCA_CTL. RCA_CTL affects the
Characteristic angle
setting.
The
Correction angle
setting can be used to improve selectivity due the inaccuracies
in the measurement transformers. The setting decreases the operation sector. The
correction can only be used with the "IoCos" or "IoSin" modes.
The polarity of the polarizing quantity can be reversed by setting the
Pol reversal
to
"True", which turns the polarizing quantity by 180 degrees.
For definitions of different directional earth-fault characteristics, see
Chapter 4.2.2.9 Directional earth-fault characteristics
in this manual.
The DIRECTION output indicates on which operating sector the operating quantity
is measured. The FAULT_DIR output indicates in which operation sector the fault
current is measured. The output is operational once the function is started.
The directional calculation module calculates several values which are presented in
the monitored data.
Table 531: Monitored data values
Monitored data values Description
ANGLE Also called operating angle, shows the angle difference be-
tween the polarizing quantity (Uo, U
2
) and operating quanti-
ty (Io, I
2
).
ANGLE_RCA The angle difference between the operating angle and Char-
acteristic angle, that is, ANGLE_RCA = ANGLE – Characteris-
tic angle.
I_OPER The current that is used for fault detection. If the Operation
mode setting is "Phase angle", "Phase angle 80" or "Phase
angle 88", I_OPER is the measured or calculated residual
current. If the Operation mode setting is "IoSin", I_OPER is
calculated as follows I_OPER = Io x sin(ANGLE). If the Opera-
tion mode setting is "IoCos", I_OPER is calculated as follows
I_OPER = Io x cos(ANGLE).
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, 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
Protection functions
1MRS759142 F
456 REX640
Technical Manual
To Next Page
Loading...
