The "Inverse reset" selection is only supported with ANSI or user
programmable types of the IDMT operating curves. If another
operating curve type is selected, an immediate reset occurs during the
drop-off situation.
The setting
Time multiplier
is used for scaling the IDMT operate and reset times.
The setting parameter
Minimum operate time
defines the minimum desired operate
time for IDMT. The setting is applicable only when the IDMT curves are used.
The
Minimum operate time
setting should be used with great care
because the operation time is according to the IDMT curve, but always
at least the value of the
Minimum operate time
setting. For more
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 operating 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.
4.4.1.5
Application
Since the negative sequence current quantities are not present during normal, balanced
load conditions, the negative sequence overcurrent protection elements can be set for
faster and more sensitive operation than the normal phase-overcurrent protection for
fault conditions occurring between two phases. The negative sequence overcurrent
protection also provides a back-up protection functionality for the feeder earth-fault
protection in solid and low resistance earthed networks.
The negative sequence overcurrent protection provides the back-up earth-fault
protection on the high voltage side of a delta-wye connected power transformer for
earth faults taking place on the wye-connected low voltage side. If an earth fault
Section 4
1MRS757454 D
Protection functions
230
611 series
Technical Manual
Summary of Contents for Relion 611 Series
Page 1: ... RELION PROTECTION AND CONTROL 611 series Technical Manual ...
Page 2: ......
Page 22: ...16 ...
Page 30: ...24 ...
Page 308: ...302 ...
Page 400: ...394 ...
Page 506: ...500 ...
Page 516: ...510 ...
Page 522: ...516 ...
Page 528: ...522 ...
Page 533: ...527 ...
Page 534: ......
Page 535: ......