GE MiCOM P40

The protection function will be trusted and NOT inhibited for questionable data for the items above which have
been set.
The protection function returns to the Normal state when the quality flags for all the necessary Sampled Value
inputs are Good. The quality flags can change with each sample, therefore there is a one-cycle transition delay
between the Normal and Inhibit states for each protection function.
4.2.1 IMPACT OF DATA QUALITY ON PROTECTION FUNCTIONS
The following table shows how Sampled Value errors affect protection functions in the IED.
For example, overcurrent protection can be configured as directional, in which case the voltage inputs have an
impact on the function. The quality of the voltage input is not important if the overcurrent is non-directional.
X means the SV input affects the Normal and Inhibit states of the protection function.
# means the protection function is affected where configured to work with this input.
$ means that frequency protection operates if any one current or voltage phase is good quality.
[I
A1
I
B1
I
C1
]
[I
A2
I
B2
I
C2
] [V
A
V
B
V
C
] V
SC1
V
SC2
I
N SEN
I
M
Differential
Protection
X # #
Distance
Protection
X # X
Directional
Earth Fault
X # X
Overcurrent
Protection
X # #
Negative
Sequence
X # #
Broken
Conductor
X #
Earth Fault
Protection
X # #
REF
Protection
X
SEF
Protection
X
Residual
Overvoltage
X
Voltage
Protection
X
Frequency
Protection
$ $ $
4.3 PROCESS BUS PERFORMANCE
Ethernet networks sometimes lose frames, so the IED tolerates some loss of samples to ensure availability of its
protection functions. The IED calculates a Frame Loss Rate every cycle for each Merging Unit (Logical Node) with
which it communicates. If the Frame Loss Rate is less than the Loss Rate Level setting (set in %), the IED tolerates
network losses of up to three consecutive samples. If the Frame Loss Rate is greater than the Loss Rate Level
setting (set in %), the protection functions are temporarily inhibited.
The IED display shows information about Sampled Value losses on the Process Bus for each Logical Node
associated with the IED in the following cells in the IEC61850-9.2LE column. This is useful during testing or
commissioning to identify and resolve any network problems which could degrade the protection scheme.
P446SV Chapter 6 - Sampled Value Operation
P446SV-TM-EN-1 99