(1) Description of Operation 7SR224
Page 58 of 66 ©2009 Siemens Protection Devices Limited
5.7 BATTERY TEST
The DC battery voltage is constantly monitored by the relay. The output function Battery Healthy is
provided to indicate that the battery charging system is connected and functioning correctly by
measurement of the ‘Float Charge’ voltage level and comparison with the minimum float voltage
based on the Battery Nominal Voltage setting.
In addition to this, the relay can be used to apply a loading test to the battery system at a settable
periodic interval. The test sequence is shown below.
If a protection Pickup occurs at any time during the test, the test will be abandoned and the charging
system re-connected. The battery voltage level will be maintained such that the Recloser will be
capable of normal operation throughout the duration of the test. Battery tests can be executed at
manual request from a binary input or from the Control Menu of the relay. If the time elapsed since the
previous battery test is less than 12 hours, the test will not execute and Test Aborted will be displayed
on the Battery Condition meter.
Figure 5.7-1 Battery Test timing diagram
When the test is required, the output Battery Test is raised to interface with external equipment. This
signal is used to disconnect the charging system and the battery is allowed to settle for a fixed period
of 30 minutes. The battery voltage with no load is then measured (V1) and the output Battery Load
Test is then raised. This is used to connect the resistive load to the battery and the voltage is
measured again after 500ms (V2). This voltage is used to asses the battery internal resistance and the
resistance of connections. If V1-V2 (ΔV) is greater than the Battery Volts Drop setting the test will be
considered as a failure and the test stopped, otherwise voltage is measured again after a further 5
seconds with the load resistance connected. This voltage, (V3), is compared to V2 and must not differ
by more than 2 volts or the test will be stopped and recorded as a fail. The load is then disconnected,
by the drop-off of the Battery Load Test output and a 10 minute recovery time applied before the
voltage is measured again (V4). This voltage must not differ from the pre-test voltage by more than 0.5
volts or Recovery Fail output will be raised. The Battery Test output is now cleared which will
reconnect the charging system to allow the system to return to normal. The quiescent voltage
monitoring will resume after 30 minutes.
To Next Page
Loading...
