Date Code 20011205
Inputs, Outputs, Timers, and Other Control Logic
7-13
SEL-311A Instruction Manual
Latch Control Switch Application Ideas
Latch control switches can be used for such applications as:
·
Circuit breaker closing enable/disable
·
Ground relay enable/disable
Latch control switches can be applied to almost any control scheme. The following is an
example of using a latch control switch to enable/disable the circuit breaker closing in the
SEL-311A Relay. This is used to prevent the circuit breaker from being closed remotely during
line or breaker maintenance.
Circuit Breaker Closing Enable/Disable Setting Example
Use a local pushbutton to enable/disable the circuit breaker closing in the SEL-311A Relay. In
this example, a contact is connected to optoisolated input IN104. Each pulse of the pushbutton
contact changes the state of the close enable. The pushbutton contact is not maintained, just
pulsed to enable/disable the circuit breaker closing.
Figure 7.12: Pushbutton Contact Pulses Input IN104 to Enable/Disable Circuit Breaker
Closing
If the circuit breaker closing is enabled and the pushbutton contact is pulsed, circuit breaker
closing is then disabled. If the pushbutton contact is pulsed again, circuit breaker closing is
enabled again. The control operates in a cyclic manner:
pulse to enable … pulse to disable … pulse to enable … pulse to disable …
This circuit breaker closing logic is implemented in the following SEL
OGIC
control equation
settings and displayed in Figure 7.13.
SET1 = /IN104 * !LT1
[= (rising edge of input IN104) AND NOT(LT1)]
RST1 = /IN104 * LT1
[= (rising edge of input IN104) AND LT1]
CL = LT1 * (CC + …)
[= (LT1); enable
CLOSE
command]
Summary of Contents for SEL-311A
Page 6: ......
Page 8: ......
Page 10: ......
Page 24: ......
Page 40: ......
Page 66: ......
Page 96: ......
Page 98: ......
Page 112: ......
Page 114: ......
Page 122: ......
Page 170: ......
Page 202: ......
Page 204: ......
Page 246: ......
Page 248: ......
Page 286: ......
Page 290: ......
Page 304: ......
Page 306: ......
Page 334: ......
Page 384: ......
Page 386: ......
Page 394: ......
Page 398: ......
Page 402: ......
Page 404: ......
Page 410: ......
Page 412: ......
Page 426: ......
Page 444: ......
Page 460: ......
Page 474: ......