The 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 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.
4.5.2.5
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
4.5.2.6
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.
The power frequency overvoltage may occur in the network due to contingencies
such as:
• The defective operation of the automatic voltage regulator when the generator
is in isolated operation.
• Operation under manual control with the voltage regulator out of service. A
sudden variation of load, in particular the reactive power component, gives
Protection functions
1MRS757644 H
642
620 series
Technical Manual
