Recloser Capacitor Test; General - Siemens 7SC80 Manual

2.23

Recloser Capacitor Test

The recloser capacity test serves for monitoring an external capacitor bank which supplies the power for
switching the recloser disconnector assigned to the 7SC80.

General

2.23.1
Overview
The actual monitoring is executed by an external switch unit driver and monitor, which displays the technical
state (healthy condition) of the capacitances in the form of two binary signals. Both signals are monitored
continuously by the 7SC80. The 7SC80 derives operational and alarm indications from the provided signals. To
start a capacity test, the 7SC80 uses a binary signal which is forwarded to the external switch unit driver and
monitor.
Monitoring is based on 2-element undervoltage monitoring. When the capacity test is started, the capacitor
bank is discharged in a defined manner via a load impedance – the capacity voltage begins to fall. First, the
voltage falls below the upper monitoring threshold, later below the lower threshold. Each time the voltage
falls below a monitoring threshold, the status of an assigned binary signal changes. From the period between
two signal transitions, the 7SC80 can draw conclusions as to the state of the capacitor bank.
When the voltage falls below the lower monitoring threshold, the test load is disconnected from the capacitor
bank. The bank is then recharged and the voltage of the capacitances starts to rise again until the upper moni-
toring threshold is exceeded. The 7SC80 monitors the time until this threshold is exceeded and can draw
conclusions about the state of the capacitor bank from that.
Further Information
The electrical drive of the recloser disconnector can be supplied by a charged capacitor bank. The technical
condition of the capacitor bank is monitored by an external switch unit driver and monitor. For this purpose, it
is equipped with 2 undervoltage detectors. Via one binary signal each, the two detectors signal the detected
voltage status to the 7SC80. The binary inputs there are 6002
Input 2 .
In the idle state, both inputs should show a logical "1". If both inputs show "0" in the idle state, the 7SC80
issues the error indication 6004
capacity test could be completed successfully.
In test mode, both inputs are used to monitor the test discharging/charging. If the function is activated, the
capacitor bank is tested cyclically. The desired time interval can be set using parameter 2802 CapTestIn-
terval. If a battery test is just running at the set starting time, the capacity test start is deferred until the end
of the battery test (30 min. after the end of the next successful battery test). To start a non-cyclical capacity
test, activate the binary input 6001
If a protection function of the 7SC80 picks up, a running capacity test is aborted and the indication 6008
Cap.test abort. is issued. Simultaneously, the indication 6005 Cap.Test active = going.
If both inputs 600x ">CapMon Input x" show logical "0", no capacity test is started; in all other cases, it is
started.
When the capacity test is started, the indication 6005
the external switch unit driver and monitor and the discharging of the capacitor bank is started there.
When the voltage falls below the upper voltage threshold, the binary signal 6003
changes from idle state logical "1" to logical "0". The binary signal 6002
logical "1". When the signal changes, the 7SC80 starts the monitoring time 2801 Cap.holdup time.
If the binary signal 6002
elapsed, it can be assumed that the charging capacity was not sufficient. The test is assessed as failed and the
7SC80 changes from test to charging mode.
Whereas, if the binary signal 6002
test is assessed as passed. In this case, the device also changes from test to charging mode and the signal
6005 Cap.Test active is reset.
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
Cap.supply fail . This indication remains active until a subsequent
>Start Cap.Test .
>CapMon Input 1 changes from logical "1" to logical "0" before this time has
>CapMon Input 1 changes after the monitoring time has expired, the
>CapMon Input 1 and 6003 >CapMon
Cap.Test active is issued. The signal is forwarded to
>CapMon Input 1 remains on
Functions
2.23 Recloser Capacitor Test
>CapMon Input 2
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