Measurements - Siemens SIPROTEC 7SJ62 Instruction Manual

Multi-functional protective relay with bay controller
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Functions
Information to a
Control Center

6.19.2 Measurements

Display of
Measured Values
6-168
In the idle condition, as long as no system fault is present, the display field can display
selected operating information (overview of operating measurement values).
In the case of a system fault, information about the system fault appears instead
(spontaneous messages). After the fault related annunciations have been cleared (ac-
knowledged), the initial display is shown again. Acknowledgment can be perfomed by
pressing the LED button on the front panel.
The relay is also equipped with several event buffers, for operational messages, circuit
breaker statistics, etc., which are protected against loss of the auxiliary voltage by a
buffer battery. These messages can be retrieved, at any time, using the operating key-
pad in the display field, or transferred to a personal computer, using the serial operat-
ing interface. Readout of messages during operation is described in detail in Subsec-
tion 7.1.1.
After a short-circuit fault on the system, for example, important information about the
progression of the fault can be retrieved, such as the pickup of a protective element or
the initiation of a trip signal. The time the initial occurrence of the short-circuit fault oc-
curred is accurately provided via the system clock. Time progression of the short-cir-
cuit fault is reported based on the moment of pickup, so that the duration, until the trip
signal is issued and interrupted, is available. The time resolution used for reporting is
1 ms.
With a personal computer and the protection data processing program DIGSI
event information can also be retrieved, with the comfort of visualization on the screen
and menu-driven processing. The data can be documented on a connected printer, or
stored and evaluated at another location, if desired.
The protective relay stores the messages from the last eight system faults. Upon the
occurrence of a ninth system fault, the oldest event is erased from the abnormal oc-
currence memory.
A system fault begins with the recognition of the fault by pickup of the protective func-
tion, and ends with the dropout of the last fault or with the expiration of the reclosing
blocking time, so several unsuccessful interruption cycles are also stored in combina-
tion. Therefore, a system fault may include several abnormal occurrences.
Stored information can also be transferred to a central control system (SCADA), using
the system interface. The transfer can take place using various transfer protocols.
A series of measured values and the values derived from them are constantly avail-
able for call up on site, or for data transfer (See table 6-7, as well as the following list).
A precondition for correctly displaying the primary and percentage values is complete
and correct entry of the nominal values for the voltage transformers, current transform-
ers, and protected equipment, in accordance with Subsections 6.1.1 and 6.1.3.
Depending on the type of device ordered and the device connections, some of the op-
erating measured values listed below may not be available. The phase-to-ground volt-
ages are either measured directly, if the voltage inputs are connected phase-to-
ground, or they are calculated from the phase-to-phase voltages V
displacement voltage V
.
0
®
4,
and V
and the
ab
bc
7SJ62 Manual
C53000-G1140-C121-1

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