Hitachi Relion 670 Series Applications Manual page 274

Section 12
Control
number of positions available on the tap changer. All mA values within one interval are then
associated with one tap changer position value.
The number of available tap changer positions N is defined by the setting parameters LowVoltTap
and HighVoltTap, which define the tap position for lowest voltage and highest voltage respectively.
12.5.3.2 Tap changer extreme positions
This feature supervises the extreme positions of the tap changer according to the settings
LowVoltTap and HighVoltTap. When the tap changer reaches its lowest/highest position, the
corresponding LOPOSAL/HIPOSAL alarm signal will be activated.
12.5.4 Setting guidelines
12.5.4.1 TCMYLTC and TCLYLTC general settings
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.
LowVoltTap: This gives the tap position for the lowest LV-voltage.
HighVoltTap: This gives the tap position for the highest LV-voltage.
mALow: The mA value that corresponds to the lowest tap position. Applicable when reading of the
tap position is made via a mA signal.
mAHigh: The mA value that corresponds to the highest tap position. Applicable when reading of the
tap position is made via a mA signal.
CodeType: This setting gives the method of tap position reading.
UseParity: Sets the parity check On/Off for tap position reading when this is made by Binary, BCD, or
Gray code.
tStable: This is the time that needs to elapse after a new tap position value is given to YLTC until it is
accepted as correct one and reported further to ATCC, TxWPDIF and SCADA.
CLFactor: This is the factor designated "a" in
load current (current measured on the HV-side), the ContactLife counter decrements with 1,
irrespective of the setting of CLFactor. The setting of this factor gives the weighting of the deviation
with respect to the load current.
InitCLCounter: The ContactLife counter monitors the remaining number of operations (decremental
counter). The setting InitCLCounter then gives the start value for the counter that is, the total number
of operations at rated load that the tap changer is designed for.
EnabTapCmd: This setting enables/disables the lower and raise commands to the tap changer. It
shall be On for voltage control, and Off for tap position feedback to the transformer differential
protection T2WPDIF or T3WPDIF.
TCMYLTC and TCLYLTC Setting group
General
Operation: Switching the TCMYLTC or TCLYLTC function On/Off.
IBase: Base current in primary Ampere for the HV-side of the transformer.
268
equation
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"". When a tap changer operates at nominal
Railway application RER670
1MRK506375-UEN Rev. N
SEMOD159053-339 v4
SEMOD171503-1 v1
SEMOD171501-150 v8
SEMOD171501-157 v3
Application manual