3. In this view, check the following settings:
3.1. Check that Control Mode is set to Manual.
3.2. Operate the tap changer so that the Load Voltage corresponds to the Voltage Set Point.
3.3. Check that neither the Raise or the Lower command are operating. Voltage Deviation should
be less than 100%.
3.4. Compare the values of Bus Voltage and Load Voltage.
UL can be obtained by a vector calculation where IL is the load current and values for RL and
XL are the settings given in primary system ohms.
~
Load
R
L
X
L
V
B
V
L
V
B
R
L
I
L
jX
L
I
L
Re
ANSI06000487-2-en.vsd
For inductive load, the Bus Voltage should be higher than the Load Voltage. If not, current circuits are
incorrect and must be reversed. Incorrect current polarity may be an issue with physical wiring or the
current direction convention selected for the CT analogue input as part of the setting in the PST setting.
12.1.2 Voltage control of Parallel Transformers
SEMOD176327-186 v5
In parallel operation, each transformer protection IED must be connected to the station communication
bus for data exchange. The following procedure assumes that the necessary pre-configuration in the
Parameter Setting tool and the Signal Matrix tool has been performed and tested to enable data
exchange between IEDs or between instances of voltage control in the same IED.
Section 12 1MRK 504 165-UUS Rev. J
Primary injection testing
294 Transformer protection RET670
Commissioning manual
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