Installation and Commissioning
8-48 7SA6 Manual
C53000-G1176-C133-1
8.3.6 Current, Voltage, and Phase Rotation Checks
Load Current
≥ 10 % I
N
The connections of the current and voltage transformers are tested using primary
quantities. Secondary load current of at least 10 % of the nominal current of the device
is necessary. The line must be energized and remains energized during this
measurement test.
With proper connections of the measuring circuits, none of the measured-values
supervision elements in the device should pick up. If an element detects a problem,
the relevant condition can be viewed in the operational annunciations (refer also to
Sub-section 7.1.1.2).
If current summation errors occur, then check the matching factors. See Sub-section
6.1.1.
Messages from the symmetry monitoring could occur because there actually are
asymmetrical conditions in the network. If these asymmetrical conditions are normal
service conditions, the corresponding monitoring functions should be made less
sensitive. See Section 6.19.2.
Quantities Currents and voltages can be viewed as primary or secondary quantities in the front
display or via the service interface with a personal computer, and compared with the
actual measured values (refer to section 7.1.3.1).
If the measured values are not plausible, the connection must be checked and
corrected after the line has been isolated and the current transformer circuits have
been short-circuited. The measurements must then be repeated.
Phase Rotation The phase rotation must correspond to the configured phase rotation, in general a
clockwise phase rotation. If the system has an anti-clockwise phase rotation, this must
have been considered when the power system data was set (address 3+$6(
6(4, refer to Sub-section 6.1.1). If the phase rotation is incorrect, the alarm “
)DLO3K6HT” (FNo ) is generated. The measured value phase allocation
must be checked and corrected, if required, after the line has been isolated and
current transformers have been short-circuited. The phase rotation check must then
be repeated.
Voltage
Transformer
Miniature Circuit
Breaker (VT mcb)
The VT mcb of the feeder must be opened. The measured voltages in the operational
measured values (Sub-section 7.1.3.1) appear with a value close to zero (small
measured voltages are of no consequence).
Check in the spontaneous messages (section 7.1.1.7) that the VT mcb trip was
entered (message “!)$,/)HHGHU9721” in the spontaneous messages).
Beforehand it has to be assured that the position of the VT mcb is connected to the
device via a binary input.
Close the VT mcb: The above messages appear under the spontaneous messages
as “2))”, i.e. “!)$,/)HHGHU97 2))”).
If one of the events does not appear, the connection and routing of these signals
(Sub-section 5.2.5) must be checked.
If the „21“–state and „2))´–state are swapped, the contact type (H–active or L–
active) must be checked and remedied (Sub-section 5.2.5).
If a busbar voltage is used (for voltage protection and synchronism check) and the
assigned VT mcb is connected to the device, the following function must also be
checked:
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