Timer Characteristics - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.2.7.6
502
the set Current start value (×In), Voltage start value (×Un) and Power start value
(×Pn) respectively. When all three quantities exceed the limits, Level detector enables
the Timer module.
As nominal power is the result of the multiplication of the nominal current and the
nominal voltage Pn = Un × In, the calculation of the setting value for Power start value
(×Pn) depends on whether Io and Uo are measured or calculated from the phase
quantities.
Timer
Once activated, Timer activates the START output. Depending on the value of the
Operating curve type setting, the time characteristics are according to DT or
wattmetric 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. If a drop-off situation happens, that is, a fault suddenly
disappears before the operating delay is exceeded, the timer reset state is activated.
The reset time is identical for both DT or wattmeter IDMT. The reset time depends on
the Reset delay time setting.
Timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operation time. The value is available
in the monitored data view.
Blocking logic
There are three operation modes in the blocking function. The operation modes are
controlled by the BLOCK input and the global setting in 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, but the OPERATE output is not
deactivated when blocking is activated. 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

In the wattmetric IDMT mode, the OPERATE output is activated based on the timer
characteristics:
1MRS759142 C
REX640
Technical Manual