Loss Of Voltage (Lov) Loop Automation Function - Siemens 7SR224 Technical Manual

Repeat the reduction of Bus and Line voltages to check the pickup and drop off of the Bus Undervolts, Line
Undervolts and Voltage Diff settings, if enabled. Outputs signals are available in the Output Matrix to allow leds or
Binary Outputs to be allocated to these functions.
Line Undervolts
Bus Undervolts
Voltage Diff
Test voltages can be manipulated to test the Check Synchronising window parameters using the Voltage Check
and In Sync outputs. The In Synch output is raised when all voltage conditions are met such that a close will be
issued during an autoreclose sequence. In Synch monitors voltage magnitude, phase difference and Slip
Frequency conditions. Voltage Check is raised when voltage magnitude conditions alone are met such that a
close will be issued if phase requirements are additionally met during an autoreclose sequence which will allow.
Voltage Check is useful during testing and fault finding but is not used in service.
CS phase leading
CS phase lagging
CS Slip
Split Angle
Split Slip
SS phase leading
SS phase lagging
SS Slip
Following controller commissioning, when the circuit is live with test connections removed, the Synchronising
Meters should be checked to ensure primary voltages are correct. With the circuit breaker closed, Bus and Line
voltages should have equal magnitudes, differential voltage and phase difference should be zero.
Voltage diff
Phase Diff
Slip
4.3

Loss of Voltage (LOV) Loop Automation Function

Loss of Voltage (LOV) Loop Automation sequences should be simulated for each applicable different fault type
with the actual relay settings required for service installed in the relay.
The relay requires that the correct indications are received at the CB auxiliary contact inputs and that the injected
current and voltage used to generate protection operations are timed to the LOV autoreclose sequence to provide
a realistic simulation of the actual system conditions.
The Instruments Menu contains Autoreclose Meters for the Autoreclose State and the Shot No. which are useful
during sequence testing.
©2010 Siemens Protection Devices Limited
Setting
Setting
Setting
Setting
Expected
0 V
0 º
0 mHz
7SR224 Argus Commissioning & Maintenance Guide
Pickup
Pickup
Pickup
Pickup
Measured
Reset
Reset
Reset
Reset
Notes
Chapter 6 Page 65 of 73