4-18 Close Logic Date Code 20010731
SEL-352-1, -2 Instruction Manual
Scheme 1 (No MOD Trip)
Figure 4.12 shows the logic used to assert the 86BFT output and the 86RS output in the Relay
Word when MOD tripping is not used.
The 86BFT trip output asserts as soon as a trip condition occurs according to the M86T SEL
OGIC
control equation. The M2 timer begins timing, waiting for the trip conditions to reset. After the
trip conditions reset and the M2 timer has expired, the 86BFT trip output is reset (deasserted).
After five seconds of the reset condition (no trip and no current), the 86RS output asserts to reset
a lockout relay or provide a “safe to reset” indication. The M1 timer deasserts the 86RS output
in one second. If a thermal failure of a trip or close resistor (CTF, TTF) exists, the 86RS output
will not assert.
Figure 4.12: 86BF TRIP and Reset Logic (Scheme 1)
Figure 4.13: Lockout Relay Control Scheme 1 Timing Diagram
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