Rockwell Automation 865 Differential Protection Relay - Manual (Page 113)

Measurement Functions 5-3
865-UM001A-EN-P – July 2009
RMS Values RMS Currents
Relay calculates the RMS value of each phase current. The
minimum and the maximum of RMS values are recorded and
stored.
2
15
2
2
2
1
...
f f f rms
I I I I + + + =
Demand Values The relay calculates average i.e. demand values of phase currents I
L1
,
I
L2
, I
L3
. The demand time is configurable from 10 minutes to 30
minutes with parameter "Demand time".
Table 5.5 – Demand Value Parameters
Parameter Value Unit Description Set
Time 10 ... 30 min Demand time (averaging time) Set
Fundamental frequency values
IL1da A Demand of phase current IL1
IL2da A Demand of phase current IL2
IL3da A Demand of phase current IL3
RMS values
IL1da A Demand of phase current IL1
IL2da A Demand of phase current IL2
IL3da A Demand of phase current IL3
Minimum and maximum values are registered with time stamps
since the latest manual clearing or since the device has been
restarted. The available registered min & max values are listed in the
following table.
Table 5.6 – Minimum and Maximum Values
Min & Max measurement Description
IL1, IL2, IL3 Phase current (fundamental frequency value)
IL1RMS, IL2RMS, IL3RMS Phase current, rms value
Io1, Io2 Residual current
f Frequency
IL1da, IL2da, IL3da Demand values of phase currents
IL1da, IL2da, IL3da (rms value) Demand values of phase currents, rms values
The clearing parameter "ClrMax" is common for all these values.
Table 5.7 – Parameters
Parameter Value Description Set
ClrMax –
Clear
Reset all minimum and maximum
values
S
Minimum and Maximum
Values