Current, Voltage, And Phase Rotation Checks - Siemens siprotec 7SA522 User Manual

8.3.1

Current, Voltage, and Phase Rotation Checks

Load Current
≥ 10 % I
N
Quantities
Phase Rotation
Voltage
Transformer
Miniature Circuit
Breaker (VT mcb)
7SA522 Manual
C53000-G1176-C119-2
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 measure-
ment test.
With proper connections of the measuring circuits, none of the measured-values su-
pervision 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 sen-
sitive. See Section 6.16.
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 correct-
ed after the line has been isolated and the current transformer circuits have been
short-circuited. The measurements must then be repeated.
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+$6(
6(4, refer to Sub-section 6.1.1). If the phase rotation is incorrect, the alarm "
)DLO 3K 6HT" (FNo ) is generated. The measured value phase allocation
must be checked and corrected, if required, after the line has been isolated and cur-
rent transformers have been short-circuited. The phase rotation check must then be
repeated.
The VT mcb of the feeder must be opened. The measured voltages in the operational
measured values (Sub-section 7.1.3.1) appear with a value close to zero (small meas-
ured voltages are of no consequence).
Check in the spontaneous messages (section 7.1.1.6) that the VT mcb trip was en-
tered (message "!)$,/ )HHGHU 97 21" in the spontaneous messages). Before-
hand 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. "!)$,/ )HHGHU 97 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 synchronism check) and the assigned VT mcb is con-
nected to the device, the following function must also be checked:
Installation and Commissioning
8-25