26
ISA – F1A First-up Automatic Reset
with no subsequent alarm state
PROCESS
SEQUENCE
ABNORMAL
OR NORMAL
FIRST ALARM
FLASHING
SEQUENCE
PROCESS
OFF
NORMAL
NORMAL
ACKNOWLEDGE
WHILE ABNORMAL
(FIRST OUT RESET)
RETURN
TO NORMAL
FIRST TO
ABNORMAL
SEQUENCE
PROCESS
ABNORMAL
ACKNOW.
AUDIBLE
SILENT
LED
LCD
N
LED
AUDIBLE
AUDIBLE
LCD
(A)
F
N
AUDIBLE
SILENT
LED
LCD
A
ON
ACKNOWLEDGE
WHILE NORMAL
(first-up reset)
Sequence features
Acknowledge and lamp test pushbuttons required
Alarm audible device
Lock-in of momentary first alarm until acknowledged. No lock-in of momentary
subsequent alarms
Flashing and audible indications for first alarm only. New subsequent alarms go to the
acknowledged state
First-up indication is reset and the audible devices silenced when acknowledged
Automatic reset of acknowledged alarms when process conditions return to normal