ABB Remote I/O RIO600 Installation And Commissioning Manual page 162

Section 6
Commissioning
154
GUID-201C1336-9482-4D26-B04B-6A04CBF73AF3 V1 EN
Figure 84: Principle of CPS
Cumulative phasor sum is the result of adding the values of the measured current
phasors together in phasor format in chronological order during the fault. Using the
discrete current phasors in different time instants (t1...t5), the corresponding
accumulated current phasor is calculated:
ΔI (t1) = ΔI (t1)
A_CPS A
ΔI (t2) = ΔI (t1)+ΔI
A_CPS A
ΔI (t3) = ΔI (t1)+ΔI
A_CPS A
ΔI (t4) = ΔI (t1)+ΔI
A_CPS A
ΔI (t5) = ΔI (t1)+ΔI
A_CPS A
By dividing two CPS-based current quantities, CPS1/CPS2, a stable magnitude or
phase angle estimate regardless of the fault type is obtained. This is demonstrated in
Figure 85 and Figure 86.
The main advantage of the CPS method is that it can estimate stable magnitude and
phase angle also during intermittent or re-striking earth faults. Accumulation of
phasors is started when the presence of an earth fault in the network is confirmed and
accumulation of phasors is reset when the fault condition is over, and after Reset Delay
Time has elapsed.
Fault passage indicator
After the presence of the earth fault in the network and the faulted phase is confirmed,
then it is the task to validate whether the fault current has flown though the
measurement point of FPIPTOC. There are two criteria for detection of fault passage
based on the theory of admittances valid for high impedance earthed network during
a single-phase earth fault.
(t2)
A
(t2) +ΔI (t3)
A A
(t2) +ΔI (t3) +ΔI (t4)
A A A
(t2) +ΔI (t3) +ΔI (t4) +ΔI
A A A
1MRS757488 H
(t5)
A
Installation and Commissioning Manual
RIO600