Siemens FEC920 User Manual page 88

DEVIATION ALARMS
Deviation low alarm definitions
Reference
Deviation
Hysteresis
Input signal
Hysteresis: 0
Hysteresis: 0
Hysteresis: yes
Hysteresis: yes
RATE-OF-CHANGE ALARMS
Symbol
A rate-of-change alarm is active if the monitored value changes by more than one 'Amount' in less
than 1 'Change time'. Dwell delays the alarm on-time. Averaging removes the effects of signal
noise.
Note: Operation of rate-of-change alarms may be affected if an input filter (Section 6.4.1) is applied
to the input signal.
Page 80
FEC920: USER GUIDE
Symbol
Dwell: 0
Dwell: D
Dwell: 0
Dwell: D
= Alarm active
Deviation band alarm definitions
Hysteresis
Deviation
Reference
Deviation
Hysteresis
Input signal
Hysteresis: 0
Dwell: 0
Hysteresis: 0
Dwell: D
Hysteresis: yes
Dwell: 0
Hysteresis: yes
Dwell: D
Figure 72 Deviation alarm parameters
Rate-of-change alarm definitions
Rate-of-change rise active
Figure 73 Rate-of-change alarm parameters
A5E45696052A Rev-AA
Deviation high alarm definitions
Hysteresis
Deviation
Reference
Input signal
Hysteresis: 0
Dwell: 0
Hysteresis: 0
Dwell: D
Hysteresis: yes
Dwell: 0
Hysteresis: yes
Dwell: D
Symbol
= Alarm active
Rate-of-change fall active
'Change Time' units
(second, minute or hour)
Symbol
= Alarm active
Symbol
Present
time
September 18