I
2
/I
1
The I
2
/I
1
module calculates the ratio of the negative and positive sequence current. It
reports the calculated value to the level detector.
Level detector
The level detector compares the calculated ratio of the negative and positive-sequence
currents to the set
Pickup value
. If the calculated value exceeds the set
Pickup value
and
the min current check module has exceeded the value of
Min phase current
, the level
detector reports the exceeding of the value to the timer.
Min current check
The min current check module checks whether the measured phase currents are above the
set
Min phase current
. At least one of the phase currents needs to be above the set limit to
enable the level detector module.
Timer
Once activated, the timer activates the
PICKUP
output. The time characteristic is
according to DT. When the operation timer has reached the value set by
Trip delay time
,
the
TRIP
output is activated. If the fault disappears before the module trips, the reset timer
is activated. If the reset timer reaches the value set by
Reset delay time
, the operation timer
resets and the
PICKUP
output is deactivated.
The timer calculates the pickup duration value PICKUP_DUR, which indicates the 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 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
TRIP
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 TRIP output" mode, the function operates normally but the
TRIP
output is not activated.
1MAC059074-MB A
Section 4
Protection functions
615 series ANSI
595
Technical Manual
Summary of Contents for Relion 615 series
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