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Date Code 20011026
Specifications
2-17
SEL-321/321-1 Instruction Manual
Trip Coil Monitor (TCM) Logic
Programmable inputs can be assigned to monitor the integrity of up to six trip-coil circuits. Each
input must be connected in parallel with the appropriate tripping contacts.
If any monitoring input disagrees with the corresponding 52A input for 60 cycles, then the TCM
element asserts. Table 2.3 shows the logic input assignments required to activate the TCM logic.
Table 2.3: Trip Coil Monitor Logic Input Assignment Options
Breaker 1
Breaker 2
3PT SPT 3PT SPT
52A1,TCM1 52AA1,
TCMA1
52AB1, TCMB1
52AC1, TCMC1
52A2,TCM2 52AA2,
TCMA2
52AB2, TCMB2
52AC2, TCMC2
Logic Output
Trip Coil
Monitor condition
TCM
Trip coil path invalid condition.
Supporting Drawing: Figure 2.42.
Close Logic
This logic controls the CC element. Remotely close a circuit breaker with the CLOSE command.
This command is available in the Breaker and Level 2 access levels. Both of these levels have
separate passwords.
Issuing the CLOSE command asserts the CC element if the breaker is open. Use a SEL
OGIC
control equation to program the CC element to any output contact connected to the closing
circuit of the breaker.
The CC element asserts for 30 cycles or until the breaker closes or a tripping condition is
detected.
Supporting Drawing: Figure 2.43.
Trip Suspicion Logic
Transferring polarizing potentials from one source to another during high loading conditions may
result in a race condition between assertion of three-phase LOP and the phase distance elements.
The Trip Suspicion logic ensures distance element security during this transfer.
Assign a relay input to monitor the device which initiates the potential transfer. The input
assignment is PTXFR. For a five second period after asserting the PTXFR input, the Trip
Suspicion logic delays tripping for 3 cycles.
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