ABB ret650 - Page 81

2Udi U UB> -
EQUATION2092 V1 EN (Equation 12)
UB Uset=
EQUATION2094 V1 EN (Equation 13)
(for the purposes of this test procedure)
Therfore:
_ 2Ci Icc i Xi U Uset× × > -
EQUATION2096 V1 EN (Equation 14)
( )
( )
2
_
U Uset
Icc i
Ci Xi
-
>
×
EQUATION2098 V1 EN (Equation 15)
9. Using the settings for USet, UDeadband, C (Compensating factor) and Xr2
(transformer short circuit impedance) calculate the magnitude of Icc_i
necessary to cause a tap change command.
10. Inject current equal to IBase (for winding 2, which is defined in a global base
function, selected with setting GlobalBaseSel2 for TR8ATCC) for
Transformer 1 and (IBase - |Icc_i|) for Transformer 2 so that the magnitude of
calculated circulating current will cause a raise command to be issued for
Transformer 2 and a lower command for Transformer 1. Magnitude and
direction of circulating currents measured for each transformer can be
observed as service values on the local HMI and raise/lower commands
detected from the binary output mapped in the Signal Matrix.
The voltage injection equal to USet is required for both
transformers during this test.
11. Confirm that a tap change command is issued from the voltage control
function to compensate for the circulating current.
12. Injected currents can be reversed such that the direction of calculated
circulating currents change polarity, which will cause a lower command for
Transformer 2 and a raise command for Transformer 1.
Circulating current limit
1MRK 504 126-UEN - Section 6
Testing functionality
73
Commissioning Manual