8-48 BE1-951 Application 9328900990 Rev L
Output Contact Latch using the TRSTKEY Logic Variable
On occasion, an application will call for latching an output contact such as simulating a lockout (86)
function. Each output contact of a Basler relay can be set to latch by using an AND gate to seal the trip
condition and the TRSTKEY logic variable to reset the latch.
As an example, assume a BE1-951 is used for overcurrent protection of a radial transformer shown in
Figure 8-15, Station One-Line Drawing. The user wants to trip and lockout the high side circuit switcher
for an overcurrent trip.
Figure 8-15. Station One-Line Drawing
Referring to
Figure 8-16, a 51 or 151 trip will causeVO11 to go high. This in turn causes VO14 to go high,
sealing the inputs of VO3 and VO4 through AND gate VO7. This allows Output Contacts 3 and 4 to
transition and remain in that state until the TRSTKEY variable is asserted. In this example, the circuit
switcher will be tripped by Output 3 (simulating an 86 "a") and its close circuit disabled by Output 4
(simulating an 86 "b"). The HMI LCD display automatically goes to the Target Screen per the automatic
display priority function. When the operator presses the reset key while the LCD display is on the Target
Screen (Reset key of the HMI is context sensitive), the TRSTKEY logic variable goes high breaking the
VO7 seal in, at which point Output 3 will open and Output 4 will close. Refer to Section 6, Reporting and
Alarm Functions, Fault Reporting, Targets.
Figure 8-16. Transformer Protection Output Latch, ARSTKEY and TRSTKEY
To Next Page
Loading...
Need help?
General