A1Hi
(alarm high setpoint)
Displays and sets the high setpoint value for alarm 1 relay. The high alarm setpoint may be disabled
by pressing the
^
and
v
pushbuttons simultaneously. When the alarm is disabled the display will indicate
OFF
. Use
^
or
v
to adjust the setpoint value if required. The alarm will activate when the displayed value is
higher than the
A1Hi
setpoint value. Each relay may be configured with both a low and high setpoint if
required, if so the relay will be activated when the display reading moves outside the band set between low
and high setpoints.
A1HY
(alarm hysteresis [deadband])
Displays and sets the alarm hysteresis
limit and is common for both high and low
setpoint values. The hysteresis value may be
used to prevent too frequent operation of the
setpoint relay when the measured value stays
close to the setpoint. Without a hysteresis
setting (
A1HY
set to zero) the alarm will activate
when the display value goes above the alarm
setpoint (for high alarm) and will reset when the
display value falls below the setpoint, this can
result in repeated on/off switching of the relay at
around the setpoint value. The hysteresis setting
operates as follows:
In the high alarm mode, once the alarm
is activated the input must fall below the setpoint
value minus the hysteresis value to reset the
alarm. e.g. if
A1Hi
is set to
50.0
and
A1Hy
is
set to
3.0
then the setpoint output relay will
activate once the display value goes above
50.0
and will reset when the display value goes
below
47.0
(50.0 minus 3.0).
In the low alarm mode, once the alarm
is activated the input must rise above the
setpoint value plus the hysteresis value to reset
the alarm.
e.g. if
A1Lo
is set to
20.0
and
A1Hy
is
set to
10.0
then the alarm output relay will
activate when the display value falls below
20.0
and will reset when the display value goes above
30.0
(20.0 plus 10.0).
The hysteresis units are expressed in displayed engineering units.
A1tt
(alarm trip time)
Displays and sets the alarm trip time and is common for both alarm high and low setpoint values.
The trip time is the delay time before the alarm relay will activate, or trip, when an alarm condition is present.
The alarm condition must be present continuously for the trip time period before the alarm will trip. This
function is useful for preventing an alarm trip due to short non critical deviations from setpoint. The trip time is
selectable over
0
to
9999
seconds.
A1rt
(alarm reset time)
Displays and sets the alarm relay reset time. With the alarm condition is removed the alarm relay will
stay in its alarm condition for the time selected as the reset time. The reset time is selectable over
0
to
9999
seconds.
Page 12 of 46
LD4LNMAN-1.0-1
Display Value
Time
A Lo
x
Setpoint
relay
activates
Setpoint
relay
resets
A HY
x
value
(hysteresis or deadband)
Display Value
Time
A Hi
x
Setpoint
relay
activates
Setpoint
relay
resets
A HY
x
value
(hysteresis or deadband)
