Hitachi Relion 670 Series Applications Manual page 153
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- Applications manual (354 pages) ,
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1MRK506375-UEN Rev. N
Choice of time delay characteristics: There are several types of time delay characteristics available
such as definite time delay and different types of inverse time delay characteristics. The selectivity
between different overcurrent protections is normally enabled by co-ordination between the function
time delays of the different protections. To enable optimal co-ordination between all overcurrent
protections, they should have the same time delay characteristic. Therefore, several inverse time
characteristics are available within D2PTOC function.
Normally, it is required that the phase overcurrent protection shall reset as fast as possible when the
current level gets lower than the operation level.
Power transformers can have a large inrush current, when being energized. This phenomenon is due
to saturation of the transformer magnetic core during parts of the period. There is a risk that inrush
current will reach levels above the pick-up current of the phase overcurrent protection. The inrush
current has a large 2
protection function. Therefore, D2PTOC has a possibility of 2
harmonic component reaches a value above a set percent of the fundamental frequency current.
8.2.4
Setting guidelines
The parameters for two-step directional phase overcurrent protection D2PTOC are set via the local
HMI or Protection and Control Manager PCM600.
Common base IED values for the primary current (IBase), primary voltage (UBase) and primary
power (SBase) are set in global base values for settings function GBASVAL.
GlobalBaseSel: Selects the global base value group used by the function to define IBase, UBase and
SBase. Note that this function will only use IBase and UBase values.
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 D2PTOC function.
For two-phase railway supply system, IBase shall be entered as:
•
Rated phase current of the protected object in primary amperes, when the measured current
quantity is selected other than phase1-phase2, which is shown in Table 18.
•
Rated phase current of the protected object in primary amperes multiplied by 2.0 (i.e.
2.0*Iphase), when the measured current quantity is selected as phase1- phase2, which is
shown in Table 18.
For two-phase railway supply system, UBase shall be entered as:
•
Rated phase-to-earth voltage of the protected object in primary kV, when the measured voltage
quantity is selected other than phase1-phase2, which is shown in Table 19.
•
Rated phase-to-phase voltage of the protected object in primary kV, when the measured voltage
quantity is selected as phase1-phase2, which is shown in Table 19.
Operation: For two-step directional phase overcurrent protection Off/On.
CurrentInput: To select the type of energizing quantity (i.e. phasor) for current and will be used as
operating quantity for operation of both overcurrent steps.
Railway application RER670
Application manual
If VT inputs are not available or not connected, the setting parameter DirModex (x = step
1, 2) shall be left to the default value Non-directional.
nd
harmonic content. This can be used to avoid unwanted operation of the
When inverse time overcurrent characteristic is selected, the operate time of the stage
will be the sum of the inverse time delay and the set definite time delay. Thus, if only the
inverse time delay is required, it is important to set the definite time delay for that stage to
zero.
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nd
harmonic restrain if the level of 2
Section 8
Current protection
nd
IP14982-1 v1
M12982-4 v15
147
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