Date Code 20001006 Breaker Monitor, Metering, and Load Profile Functions 8-17
SEL-351 Instruction Manual
DCLO > DCHI (Bottom of Figure 8.10)
Output contact OUT9 asserts when:
DCHIP £ V
dc
£ DCLOP
Pickup settings DCLOP and DCHIP are set such that output contact OUT9 asserts when dc
battery voltage stays between allowable limits.
If the relay loses power entirely (V
dc
= 0 Vdc)
V
dc
= < DCHIP
then output contact OUT9 should logically deassert (according to bottom of Figure 8.10), and this
is surely what happens for a total loss of power (all output contacts deassert on total loss of
power).
Output Contact Type Considerations (“a” or “b”)
Refer to Output Contacts in Section 7: Inputs, Outputs, Timers, and Other Control Logic
(especially Note 2 in Figure 7.28). Consider the output contact type (“a” or “b”) needed for output
contact OUT9 in the bottom of Figure 8.10 (dc voltage alarm example).
If SELOGIC Control Equation setting OUT9 is asserted (OUT9 = SV4T = logical 1; dc voltage
OK), the state of output contact OUT9 (according to contact type) is:
closed (“a” type output contact)
open (“b” type output contact)
If SELOGIC Control Equation setting OUT9 is deasserted (OUT9 = SV4T = logical 0; dc voltage
not OK), the state of output contact OUT9 (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 OUT9
(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) + ...]
Courtesy of NationalSwitchgear.com
To Next Page
Loading...
