ABB Remote I/O RIO600 Installation And Commissioning Manual page 137

1MRS757488 H
RIO600
Installation and Commissioning Manual
value, which is lower than the total resistive earth-fault current to enable dependable
operation.
For example, if the resistive current of the parallel resistor is 10 A (at primary voltage
level), then a value of 0.5 ⋅ 10 A = 5 A could be used. If Operating Quantity is set to
"Adaptive", the same setting value is also applicable if the coil is disconnected and the
network becomes unearthed. In this case, the current magnitude supervision is
automatically based on the amplitude of
exceed the ampere value of the parallel resistor to allow the operation of the faulted
feeder. In case of a smaller ampere value of a parallel resistor, for example 5 A, the
recommended security factor should be larger, for example 0.7.
If Operating Quantity is set to "Amplitude", the set minimum operate current
threshold (settings Min Forward Operate Current and Min Reverse Operate Current)
should be selected based on the capacitive earth-fault current values produced by the
background network in case of a solid earth fault with a security margin.
The main task of the current magnitude supervision is to secure the
correct directional determination of an earth fault, so that only the
faulty feeder is disconnected or alarmed. Therefore, the threshold
values should be selected carefully and not set too high as this can
inhibit the disconnection of the faulty feeder.
Transient detector
The transient detector module is used for detecting transients in the residual current
and residual voltage signals. When the number of detected transients equals or
exceeds the Peak Counter Limit setting (without the function being reset, depending
on the drop-off time set with the Reset delay time setting), the MFAPSDE_InEF
output is activated over GOOSE. This indicates the detection of intermittent earth
fault in the network. The operation of transient detector is illustrated in
Several factors, such as the fault moment on the voltage wave, fault
location, fault resistance and the parameters of the feeders and the
supplying transformers, affect the magnitude and frequency of fault
transients. If the fault is permanent (non-transient) in nature, only the
initial fault transient in current and voltage can be measured, whereas
the intermittent fault creates repetitive transients. The practical
sensitivity of transient detection is limited to approximately few
hundreds of ohms of fault resistance. Therefore, the application of
transient detection is limited to low ohmic earth faults.
Commissioning
1
I
). The selected setting value must never
0
stab
Section 6
Figure 75.
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