Timer Characteristics - ABB RELION 620 Series Technical Manual

Section 4
Protection functions
4.2.6.5
300
Timer calculates the pickup duration value PICKUP_DUR, which indicates the
percentage ratio of the pickup situation and the set trip 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
trip 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 TRIP output" mode, the function operates
normally but the TRIP output is not activated.

Timer characteristics

24 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 Trip delay time and Reset delay time settings.
24 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 trip time depends on the momentary value of the excitation:
the higher the excitation level, the shorter the trip time. The trip time calculation or
integration starts immediately when the excitation level exceeds the set Pickup value and
the PICKUP output is activated.
The TRIP output is activated when the cumulative sum of the integrator calculating the
overexcitation situation exceeds the value set by the inverse time mode. The set value
depends on the selected curve type and the setting values used.
The Minimum trip time and Maximum trip time settings define the minimum trip time and
maximum trip time possible for the IDMT mode. For setting these parameters, a careful
study of the particular IDMT curves is recommended.
1MAC504801-IB E
620 series ANSI
Technical Manual