Table 411: Restraint current selection for CVGAPC function
Set value for the
parameter
RestrCurr
Comment
1 PosSeq CVGAPC function will measure internally calculated positive sequence current phasor
2 NegSeq CVGAPC function will measure internally calculated negative sequence current phasor
3 3ZeroSeq CVGAPC function will measure internally calculated zero sequence current phasor
multiplied by factor 3
4 MaxPh CVGAPC function will measure current phasor of the phase with maximum magnitude
11.1.7.2 Base quantities for CVGAPC function
M13751-133 v3
The parameter settings for the base quantities, which represent the base (100%) for pickup levels
of all measuring stages, shall be entered as setting parameters for every CVGAPC function.
Base current shall be entered as:
1. rated phase current of the protected object in primary amperes, when the measured Current
Quantity is selected from 1 to 9, as shown in table
409.
2. rated phase current of the protected object in primary amperes multiplied by √3
(1.732*Iphase), when the measured Current Quantity is selected from 10 to 15, as shown in
table
409.
Base voltage shall be entered as:
1. rated phase-to-ground voltage of the protected object in primary kV, when the measured
Voltage Quantity is selected from 1 to 9, as shown in table
410.
2. rated phase-to-phase voltage of the protected object in primary kV, when the measured
Voltage Quantity is selected from 10 to 15, as shown in table 410.
11.1.7.3 Built-in overcurrent protection steps
M13751-136 v3
Two overcurrent protection steps are available. They are absolutely identical and therefore only
one will be explained here.
Overcurrent step simply compares the magnitude of the measured current quantity (see
table
409) with the set pickup level. Non-directional overcurrent step will pickup if the magnitude
of the measured current quantity is bigger than this set level. However depending on other
enabled built-in features this overcurrent pickup might not cause the overcurrent step pickup
signal. Pickup signal will only come if all of the enabled built-in features in the overcurrent step are
fulfilled at the same time.
Second harmonic feature
M13751-254 v2
The overcurrent protection step can be restrained by a second harmonic component in the
measured current quantity (see table
409). However it shall be noted that this feature is not
applicable when one of the following measured currents is selected:
•
PosSeq
(positive sequence current)
•
NegSeq
(negative sequence current)
•
UnbalancePh
(unbalance phase current)
•
UnbalancePh-Ph
(unbalance ph-ph current)
Section 11 1MRK 502 066-UUS B
Multipurpose protection
700
Technical manual
To Next Page
Loading...
