CD Automation srl
pag. 34 di 121
2)
Band Alarm
We define "Contolling system" any automated system capable of performing the necessary actions to
maintain the controlled variable (which usually coincides with the measured variable) as close as possible to
a certain value (which is called set point)
The band alarm is a type of alarm that can only be done on a " Contolling system" beacuse it links the value
of the threshold on the Set point (
SP
).
In the Band alarm, the alarm threshold defines an area around the set point.
Again there are
two possibilities
:
A) ON
State
when the measure is
within
the bandwidth [(SP - SA)< M < (SP + SA)]
B) ON
State
when the measure is
outside
the bandwidth [M<(SP - SA) or M>(SP + SA)]
A)
ON
State
within
the bandwidth
B)
ON
State
outside
the bandwidth
