ABB RED615 Technical Manual page 395

1YHT530004D05 D
615 series
Technical Manual
The Tap nominal parameter tells the number of the tap, which results in the
nominal voltage (and current). When the current tap position deviates from this
value, the input current values on the side where the tap changer resides are scaled
to match the currents on the other side.
A correct scaling is determined by the number of steps and the direction of the
deviation from the nominal tap and the percentage change in voltage resulting from
a deviation of one tap step. The percentage value is set using the Step of tap parameter.
The operating range of the tap changer is defined by the Min winding tap and Max
winding tap parameters. The Min winding tap parameter tells the tap position
number resulting in the minimum effective number of winding turns on the side of
the transformer where the tap changer is connected. Correspondingly, the Max
winding tap parameter tells the tap position number resulting in the maximum
effective number of winding turns.
The Min winding tap and Max winding tap parameters help the tap position
compensation algorithm know in which direction the compensation is being made.
This ensures also that if the current tap position information is corrupted for some
reason, the automatic tap changer position adaptation does not try to adapt to any
unrealistic position values.
GUID-317C68F8-A517-458A-A5D0-32FCE6C5F547 V1 EN
Figure 207: Simplified presentation of the high voltage and medium voltage
windings with demonstration of the Max winding tap, Min winding
tap and Tap nominal parameters
The position value is available through the Monitored data view on LHMI or
through other communication tools in the tap position indication function. When
the quality of the TAP_POS value is not good, the position information in
TAP_POS is not used but the last value with the good quality information is used
instead. In addition, the minimum sensitivity of the biased stage, set by the Low
operate value setting, is automatically desensitized with the total range of the tap
position correction. The new acting low operate value is
Desensitized Low operate value = Low operate value ABS MaxWi
GUID-2E5AD399-D8DD-4F64-A194-7540D55DB8ED V3 EN
Protection functions
+ ( n n ding tap Min winding tap −
Section 4
× ) Step of tap
(Equation 49)
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