8.22
SEL-400 Series Relays Instruction Manual Date Code 20171006
Monitoring
Station DC Battery System Monitor
The dc battery monitor measures the station battery voltage applied at the rear-
panel terminals labeled Vdc1 (+ and –) and Vdc2 (+ and –). Monitoring dc volt-
age during circuit breaker operation gives a quick test of the battery system,
which includes wiring and junctions from the batteries to the circuit breaker. In
the breaker report and in the breaker history report, the relay displays the mini-
mum value of station battery voltage during circuit breaker operation on a per-
pole basis.
NOTE: First enable Station DC
Monitoring (with the Global setting
EDCMON) to access station dc battery
monitor settings.
Table 8.7 lists the station dc battery monitor settings and the corresponding Relay
Word bits that assert when battery quantities exceed these settings thresholds.
Use the SET G ASCII command from a terminal or use the QuickSet Global >
Station DC Monitoring branch of the Settings tree view to access the DC Moni-
tor settings.
Station DC Battery System Monitor Application
In addition to providing a view of how much the station dc battery voltage dips
when tripping, closing, and when other dc control functions occur, the dc monitor
also alarms for under- or overvoltage dc battery conditions in five sensing
regions. The following describes how to apply the dc battery monitor to a typical
125 Vdc protection battery system with a 48 Vdc communications equipment
battery system. Adjust the values used here to meet the specifications of your
company.
Battery Voltage
When setting the station dc battery monitor, you must determine the minimum
and maximum dc levels in the battery system. In addition, you must also establish
the threshold levels for different battery system states or conditions. The follow-
ing voltage levels describe these battery system conditions:
➤ Trip/Close—the lowest dc voltage point at which circuit breaker trip
and close operations occur
➤ Open-circuit—the dc battery voltage when all cells are fully charged
and not connected to the battery charger
➤ Float low—the lowest charging voltage supplied by the battery
charger
➤ Float high—the highest charging voltage supplied by the battery
charger
➤ Equalize mode—a procedure during which the batteries are
overcharged intentionally for a preselected time in order to bring all
cells to a uniform output
Table 8.7 DC Monitor Settings and Relay Word Bit Alarms
Setting
a
a
For DC2 Monitor Settings and Relay Word bit Alarms, substitute 2 for 1 in the setting names and
Relay Word bit names.
Definition Relay Word Bit
a
DC1LFP Low Level Fail Pickup (OFF, 15–300 Vdc) DC1F
DC1LWP Low Level Warn Pickup (OFF, 15–300 Vdc) DC1W
DC1HWP High Level Warn Pickup (OFF, 15–300 Vdc) DC1W
DC1HFP High Level Fail Pickup (OFF, 15–300 Vdc) DC1F
DC1RP Peak to Peak AC Ripple Pickup (1–300 Vac) DC1R
DC1GF Ground Detection Factor (1.00–2.00) (advanced setting) DC1G
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