Omega RD100B manual Alarms, Alarm Types

1.3 Alarms

This function generates an alarm when the measured data meets a certain condition. The alarm occurrence/release can be recorded on the chart paper. The alarm status can be displayed on the screen.

Also, alarm output relays can be used to output contact signals when alarms occur (/A1, /A2, and /A3 options).

Alarm Types

Number of Alarm Point Marks

Up to four alarms can be set for each channel.

Alarm Conditions

The eight conditions below are available. The character inside the parentheses is the symbol used to denote each alarm on the recorder.

•High Limit Alarm (H)

An alarm occurs when the input value exceeds the alarm value.

•Low Limit Alarm (L)

An alarm occurs when the input value falls below the alarm value.

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Functional Description

High limit alarm
Alarm occurrence	Alarm
	value
Alarm release
Measured value

Low limit alarm

Measured	Alarm release
value
Alarm occurrence		Alarm value

•Difference High Limit Alarm (h)*

An alarm occurs when the difference in the input values of two channels is greater than or equal to the specified value.

•Difference Low Limit Alarm (l)*

An alarm occurs when the difference in the input values of two channels is less than or equal to the specified value.

*Can be specified on channels set to delta computation.

•High Limit on Rate-of-Change Alarm (R)

The rate-of-change of the measured values is checked over a certain time (interval). An alarm occurs if the rate-of-change of the measured value in the rising direction is greater than or equal to the specified value.

•Low Limit on Rate-of-Change Alarm (r)

The rate-of-change of the measured values is checked over a certain time (interval). An alarm occurs if the rate-of-change of the measured value in the falling direction is

greater than or equal to the specified value.

High limit on rate-of-change alarm Low limit on rate-of-change alarm

				Change in the
				measured value
Measured	T2
value
				Amount of change
				in the setting
	T1			T2−T1
	t1	t2−t1	t2	Time
		Interval

Measured T1
value			Amount of change
T2			in the setting
			T2−T1
			Change in the
			measured value
t1	t2−t1	t2	Time
	Interval

The alarm value of the rate-of-change alarm is set using an absolute value. The interval is derived using the following equation and set using the number of samples.

Interval = the scan interval ⋅ the number of samples

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