Timer Characteristics - ABB RELION REX640 Technical Manual

1MRS759142 C
4.5.7.6
REX640
Technical Manual
of overexcitation. The Time multiplier setting is used for scaling the IDMT operate
times.
The activation of the OPERATE output activates the BLK_RESTART output.
For the DT characteristics, the deactivation of the OPERATE output activates the
cooling timer. The timer is set to the value entered in the Cooling time setting. The
BLK_RESTART and COOL_ACTIVE outputs are kept active until the cooling timer
is reset. If the excitation increases above the set value during this period, the
OPERATE output is activated immediately. For IDMT, the deactivation of
BLK_RESTART and COOL_ACTIVE depends on the curve type selected.
The T_ENARESTART output indicates in seconds the duration for which the
BLK_RESTART output still remains active. The value is available in the Monitored
data view.
Timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operating time. The value is available
in the Monitored data view.
Blocking logic
There are three operation modes in the blocking functionality. The operation modes
are controlled by the BLOCK input and the global setting Configuration/System/
Blocking mode which selects the blocking mode. The BLOCK input can be controlled
by a binary input, a horizontal communication input or an internal signal of the
protection relay's program. The influence of the BLOCK signal activation is
preselected with the global setting Blocking mode.
The Blocking mode setting has three blocking methods. In the "Freeze timers" mode,
the operation timer is frozen to the prevailing value. In the "Block all" mode, the whole
function is blocked and the timers are reset. In the "Block OPERATE output" mode,
the function operates normally but the OPERATE output is not activated.

Timer characteristics

OEPVPH supports both DT and IDMT characteristics. The DT timer characteristics
can be selected as "ANSI Def. Time" or "IEC Def. Time" in the Operating curve type
setting. The functionality is identical in both cases. When the DT characteristics are
selected, the functionality is only affected by the Operate delay time and Reset delay
time settings.
OEPVPH also supports four overexcitation IDMT characteristic curves: "OvExt
IDMT Crv1", "OvExt IDMT Crv2", "OvExt IDMT Crv3" and "OvExt IDMT Crv4".
Overexcitation inverse definite minimum time curve (IDMT)
In the inverse time modes, the operate time depends on the momentary value of the
excitation: the higher the excitation level, the shorter the operate time. The operate
Section 4
Protection functions
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