Schweitzer Engineering Laboratories SEL-311C - Additional Application; View Station DC Battery Voltage; Analyze Station DC Battery Voltage

8.17
Date Code 20060320 Instruction Manual SEL-311C Relay
Breaker Monitor and Metering Functions
Station DC Battery Monitor
Output Contact Type Considerations (a or b)
Refer to Output Contacts on page 7.32 (especially w in Figure 7.28).
Consider the output contact type (a or b) needed for output contact OUT106 in
the bottom of Figure 8.10 (dc voltage alarm example).
If SEL
OGIC control equation setting OUT106 is asserted (OUT106 = SV4T =
logical 1; dc voltage OK), the state of output contact OUT106 (according to
contact type) is:
➤ closed (a type output contact)
➤ open (b type output contact)
If SEL
OGIC control equation setting OUT106 is deasserted (OUT106 = SV4T
= logical 0; dc voltage not OK), the state of output contact OUT106 (according
to contact type) is:
➤ open (a type output contact)
➤ closed (b type output contact)
If the relay loses power entirely, all output contacts deassert, and the state of
output contact OUT106 (according to contact type) is:
➤ open (a type output contact)
➤ closed (b type output contact)
Additional
Application
Other than alarming, the dc voltage elements can be used to disable reclosing.
For example, if the station dc batteries have a problem and the station dc
battery voltage is declining, drive the reclosing relay to lockout:
79DTL = !SV4T + ... [= NOT(SV4T) + ...]
Timer output SV4T is from the bottom of Figure 8.10. When dc voltage falls
below pickup DCHIP, timer output SV4T drops out (= logical 0), driving the
relay to lockout:
79DTL = !SV4T + ... = NOT(SV4T) + ... = NOT(logical 0) + ... = logical 1
View Station DC
Battery Voltage
Via Serial Port
See MET k-Instantaneous Metering on page 10.20. The MET command
displays the station dc battery voltage (labeled VDC).
Via Front Panel
The information available via the previously discussed MET serial port
command is also available via the front-panel {METER} pushbutton. See
Figure 11.2.
Analyze Station DC
Battery Voltage
See Standard 15/30/60/180-Cycle Event Reports on page 12.2. The station dc
battery voltage is displayed in column
Vdc in the example event report in
Figure 12.3. Changes in station dc battery voltage for an event (e.g., circuit
breaker tripping) can be observed. Use the EVE command to retrieve event
reports as discussed in Section 12: Standard Event Reports and SER.