ABB RET670 - Page 583

Zero sequence based
The IED setting value 3V0PU is given in percentage of the base voltage VBase, where
VBase is the primary base voltage, normally the rated voltage of the primary potential
voltage transformer winding. The setting of 3V0PU should not be set lower than
according to equation
416.
3 0
3 0 100= ×
V
V PU
VBase
EQUATION1759-ANSI V3 EN (Equation 416)
where:
3V0 is the maximal zero sequence voltage during normal operation conditions, plus a margin of 10...20%
VBase is the setting of base voltage for the function
The setting of the current limit 3I0> is done in percentage of IBase. The setting of
pickup must be higher than the normal unbalance current that might exist in the
system. The setting can be calculated according to equation 417.
3 0
3 0 100= ×
I
I PU
IBase
EQUATION2293-ANSI V2 EN (Equation 417)
where:
3I0PU is the maximal zero sequence current during normal operating conditions, plus a margin of 10...20%
IBase is the setting of base current for the function
Delta V and delta I
Set the operation mode selector OpDVDI to Enabled if the delta function shall be in
operation.
The setting of DVPU should be set high (approximately 60% of VBase) and the current
threshold DIPU low (approximately 10% of IBase) to avoid unwanted operation due to
normal switching conditions in the network. The delta current and delta voltage
function shall always be used together with either the negative or zero sequence
algorithm. If VSetprim is the primary voltage for operation of dU/dt and ISetprim the
primary current for operation of dI/dt, the setting of DVPU and DIPU will be given
according to equation
418 and equation 419.
1MRK504116-UUS C Section 3
IED application
577
Application manual