Hitachi Relion 670 Series Applications Manual page 79

1MRK506375-UEN Rev. N
way, ToObject or FromObject. However, internally REFPDIF always uses reference directions
towards the protected transformers 31. Thus the IED always measures the primary currents on all
sides and in the neutral of the power transformer with the same reference direction towards the
power transformer winding.
The main CT's connection type can be freely selected for each of the involved current transformers.
6.1.3.3 Railway specific applications for REFPDIF function
If appropriate configuration and settings are applied, the REFPDIF function can also be used for the
following special applications in the railway supply system:
• Defrost protection, when a single phase differential protection is temporary arranged among two
CTs during de-icing operation of the catenary contact line wires.
• Single phase differential protection applied across one winding (i.e. either over one single-phase
transformer winding or a generator winding).
6.1.4 Setting guidelines
6.1.4.1 Setting and configuration
Recommendation for analog inputs
ISI: Neutral current input.
I2P: Phase currents from winding HV side current transformer set.
Recommendation for Binary input signals
BLOCK: The input will block the operation of the function. It can be used, for example, to block the
operation during special service conditions for a limited time.
Recommendation for output signals
START: The start output indicates that Idiff is in the operate region of the operate-restraint
characteristic.
TRIP: The trip output is activated when all operating criteria are fulfilled.
DIROK: The output is activated when the directional criteria has been fulfilled.
BLK2H: The output is activated when the function is blocked due to high level of second harmonic.
6.1.4.2 Settings
The parameters for the restricted earth fault protection, low impedance function REFPDIF are set via
the local HMI or PCM600.
Common base IED values for primary current (IBase), primary voltage ( UBase ) and primary power
(SBase) are set in a Global base values for settings function GBASVAL.
GlobalBaseSel: To select a GBASVAL function for reference of base values.
Operation: The operation of REFPDIF can be switched On/Off.
IdMin: The setting gives the minimum operation value. The setting is in percent of the IBase value of
the chosen GlobalBaseSel. For function operation, the neutral current must be larger than half of this
value. A recommended setting is 30% of power transformer-winding rated current for a solidly
earthed winding.
Railway application RER670
Application manual
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Section 6
Differential protection
GUID-F8184D63-C28F-4016-BDE8-CD1B081105CA v1
IP14942-1 v1
M13052-3 v3
M13052-8 v10
M13052-17 v8
M13052-21 v9
M13052-28 v15
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