ABB RELION 620 Series Technical Manual page 644

Section 4
Protection functions
4.5.2.5
4.5.2.6
638
the value of the Minimum operate time setting. For more information,
see the IDMT curves for overcurrent protection section in this manual.
The Timer calculates the start duration value START_DUR which indicates the
percentage ratio of the start situation and the set operate 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 relay
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.
The "Freeze timers" mode of blocking has no effect during the inverse
reset mode.
Timer characteristics
PHAPTOV supports several operating curve types.
Table 583: Timer characteristics supported by IDMT operate curve types
Operating curve type
(5) ANSI Def. Time
(15) IEC Def. Time
(17) Inv. Curve A
(18) Inv. Curve B
(19) Inv. Curve C
(20) Programmable
Application
Overvoltage in a network occurs either due to the transient surges on the network or
due to prolonged power frequency overvoltages. Surge arresters are used to protect the
network against the transient overvoltages, but the relay protection function is used to
protect against power frequency overvoltages.
1MRS757644 F
620 series
Technical Manual