Yokogawa Button Operated MV2000 - Manual (Page 13)

1-6 M-4660
1.3 Alarms
This function generates an alarm when the measured data meets a set condition. You
can set a maximum of four different alarms on each channel.
Alarm Types
You can use the types of alarms listed below. The letters contained in parentheses are
used as abbreviations for the alarms.
For alarm configuration instructions, see section 3.7.
High Limit Alarm (H)
Alarm value
Alarm output ON Alarm output ON
Alarm output ON Alarm output ON
Alarm value
Hysteresis Measured value Measured value Hysteresis
Low Limit Alarm (L)
Alarm output ON Alarm output ON
Delay time Delay time
Alarm value Alarm value
Measured value Measured value
Delay High Limit Alarm (T) Delay Low Limit Alarm (t)
High Limit on Rate-of-Change Alarm (R) Low Limit on Rate-of-Change Alarm (r)
Alarm value
Alarm value
Hysteresis Hysteresis
Difference in the measured values of two channels Difference in the measured values of two channels
Difference High Limit Alarm (h) Difference Low Limit Alarm (l)
Change in the
measured value
Change in the measured value
Measured value Measured value
Time Time
Interval (t2-t1) Interval (t2-t1)
Amount of change in
the setting
|
|
T2
T1
t1 t2
T2
T1
t1 t2
T2-T1
Amount of change in
the setting
| T2-T1 |
• Hysteresis
You can set a difference between the value that activates an alarm and the value that
deactivates it.
For configuration instructions, see section 3.5.
• Delay High Limit Alarm and Delay Low Limit Alarm
If the measured value remains above or below the set alarm value for the set period of
time (the delay time), an alarm is activated.
• High Limit on Rate-of-Change Alarm and Low Limit on Rate-of-Change
Alarm
The MV checks the rate-of-change of the measured values over a set period of time (the
interval) and activates an alarm if the rate-of-change in the rising or falling direction is
greater than or equal to the set value.
The alarm value of the rate-of-change alarm is set using an absolute value. The
interval is derived from the sampling count using the following equation:
Interval = scan interval × sampling count
For instructions on how to set the interval, see section 3.5.
• Difference High Limit Alarm and Difference Low Limit Alarm
The MV activates an alarm when the difference between the values of two channels
goes above or below the set value. You can use this alarm on measurement channels
set to difference computation.