Setting Guidelines - ABB REC670 Applications Manual

Section 8
Current protection
8.1.3
8.1.3.1
142

Setting guidelines

The parameters for instantaneous phase overcurrent protection PHPIOC are set via
the local HMI or PCM600.
This protection function must operate only in a selective way. So check all system
and transient conditions that could cause its unwanted operation.
Only detailed network studies can determine the operating conditions under which
the highest possible fault current is expected on the line. In most cases, this current
appears during three-phase fault conditions. But also examine single-phase-to-earth
and two-phase-to-earth conditions.
Also study transients that could cause a high increase of the line current for short
times. A typical example is a transmission line with a power transformer at the
remote end, which can cause high inrush current when connected to the network
and can thus also cause the operation of the built-in, instantaneous, overcurrent
protection.
Common base IED values for primary current (IBase), primary voltage (UBase)
and primary power (SBase) are set in the global base values for settings function
GBASVAL.
GlobalBaseSel: This is used to select GBASVAL function for reference of base
values.
Operation: Set the protection to On/Off.
OpMode: This parameter can be set to 2 out of 3 or 1 out of 3. The setting controls
the minimum number of phase currents that must be larger than the set operate
current IP>> for operation. Normally this parameter is set to 1 out of 3and will
thus detect all fault types. If the protection is to be used mainly for multi phase
faults, 2 out of 3 should be chosen.
IP>>: Set operate current in % of IB.
IP>>Max and IP>>Min should only be changed if remote setting of operation
current level, IP>>, is used. The limits are used for decreasing the used range of
the IP>> setting. If IP>> is set outside IP>>Max and IP>>Min, the closest of the
limits to IP>> is used by the function. If IP>>Max is smaller than IP>>Min, the
limits are swapped.
StValMult: The set operate current can be changed by activation of the binary input
ENMULT to the set factor StValMult.
Meshed network without parallel line
The following fault calculations have to be done for three-phase, single-phase-to-
earth and two-phase-to-earth faults. With reference to Figure 55, apply a fault in B
and then calculate the current through-fault phase current I
1MRK 511 401-UEN A
IP14979-1 v1
M12915-4 v9
M12915-9 v8
. The calculation
fB
Bay control REC670 2.2 IEC
Application manual