7SG164 Ohmega 400 Series Impedance Functions
element. A longer time delay is used for the DC SOTF logic (400ms rather than 200ms) because it
needs to incorporate the closing time for the circuit breaker, also.
The status input ‘Start Aux DC SOTF’ is connected to a CB auxiliary contact to signal CB closing. This
function operates similarly to the Manual Close DC SOTF except that the CB aux contact must
indicate that the CB is open for the ‘Min Aux DC SOTF Dead Time’ (default -= 10secs). This assures
that the SOTF is not in operation during recloses during an auto reclose sequence and only during
manual closing operations.
1.8.3 Settings
The settings menu for the SOTF function is contained in the AUX PROTECTION Menu and
contains the following settings:
Switch On To Fault
Disable /
Enable
SOTF Mode
AC SOTF
/ DC SOTF
SOTF O/C Operate Level
0.3..4
(0.3xIn)
AC SOTF Pickup Delay
0..60000ms
(10000)
Min AUX DC SOTF Dead Time
0..60000ms
(10000)
DC SOTF Active Timer
0..60000ms (
400
)
Status Inputs:
DC SOTF MANUAL CLOSE
START AUX DC SOTF
Relay Outputs:
SOTF OPERATED
©2010 Siemens Protection Devices Limited
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