8-16 Breaker Monitor, Metering, and Load Profile Functions Date Code 20001006
SEL-351 Instruction Manual
Figure 8.10: Create DC Voltage Elements with SELOGIC Control Equations
DCLO < DCHI (Top of Figure 8.10)
Output contact OUT9 asserts when:
V
dc
£ DCLOP or V
dc
³ DCHIP
Pickup settings DCLOP and DCHIP are set such that output contact OUT9 asserts when dc
battery voltage goes below or above allowable limits.
If the relay loses power entirely (V
dc
= 0 Vdc)
V
dc
= < DCLOP
then output contact OUT9 should logically assert (according to top of Figure 8.10), but cannot
because of the total loss of power (all output contacts deassert on total loss of power). Thus, the
resultant dc voltage element at the bottom of Figure 8.10 would probably be a better choice – see
following discussion.
Courtesy of NationalSwitchgear.com
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