Schweitzer Engineering Laboratories SEL-587Z, Instruction Manual, Page: 69 / 276

4.3
Date Code 20020903
SEL-587Z Instruction Manual
Control Logic
Optoisolated Inputs
EXAMPLE 4.2 Input Settings
Use Relay Word bit IN1 as the breaker input for the SEL
OGIC
control
equation close circuit breaker status setting:
52A = IN1
Circuit Breaker Status
Connect input IN1 to a 52a circuit breaker auxiliary contact. Just
because Relay Word bit IN1 is assigned to the circuit breaker status
setting 52A does not mean that Relay Word bit IN1 cannot be used in
other SEL
OGIC
control equation settings.
More Settings
Examples
EXAMPLE 4.3 External Breaker Fail Input
Consider a breaker-and-a-half bus, as shown in Figure 4.2 , with an
SEL-587Z installed on each bus. Optoisolated input IN2 triggers the
SEL-587Z to protect against bus faults, with a trip output contact
from the relay operating an external 86 lockout relay.
Figure 4.2 Breaker-and-a-Half Bus.
Make the following assignments to close the relay output contact for
a differential element operation.
Assign the differential element Relay Word bits to internal trip logic
TR1. Thus, when any differential Relay Word bits assert (= logical 1),
the TR1 Relay Word bit also asserts.
TR1 = 87A1 + 87B1 + 87C1
Trip Conditions
Assign TRIP1 (output from the internal trip logic TR1) to Output
Contact 1. When TR1 asserts, TRIP1 also asserts, which in turn asserts
OUT1 (see
Trip Logic (TRn, ULTRn, TDURD) on page 4.16 ).
OUT1 = TRIP1
Output Contact OUT1
To further protect the power system, use the same wiring for bus
strip protection. For an external breaker fail input, wire the individual
breaker fail relay outputs from all protection relays associated with
that particular zone to input IN2 and reconfigure the relay as follows:
Assign Input 2 to SEL
OGIC
control equation variable 7.
SV7 = IN2
SEL
OGIC
Variable SV7
Assign additional debounce time delay.
SV7T = 0.5 cycle
Add SV7T to the TR1 logic.
TR1 = SV7T + 87A1 + 87B1 + 87C1
Trip Conditions
As before, assign the output to operate the 86 lockout relay.
OUT1 = TRIP1
Output Contact OUT1
52
52
52
52
52
52
52
52
52
SEL-587Z SEL-587Z
Bus Bus