1.3 Alarms

Delay High Limit Alarm (T)

An alarm occurs when the measured value remains above the alarm value for a specified time period (alarm delay period).

Delay Low Limit Alarm (t)

An alarm occurs when the measured value remains below the alarm value for a specified time period (alarm delay period).

Delay High Limit Alarm Example (T is the specified delay)

 

Measured value

 

 

 

 

 

 

 

X1

X2

X3

X4

 

 

 

 

 

 

 

 

 

Alarm value

 

 

 

 

 

 

 

 

 

 

T1

 

 

 

T

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alarm occurrence

Alarm release

Alarm does not occur at T1, because the time period is shorter than the specified alarm delay period (T).

The measured value exceeds the alarm value at time X2, and the alarm occurs at time X3 at which the specified alarm delay period elapses (the time when the alarm occurs is the time at X3).

The measured value falls below the alarm value at time X4, and the alarm is released.

Note

The alarm detection operation is reset when a power failure occurs. The operation restarts after the power recovers.

If the alarm value is changed while a delay alarm is occurring, the alarm is released if the new alarm value does not meet the alarm condition.

Alarm Hysteresis

Hysteresis can be specified to the values for activating and releasing the alarm. The hysteresis applies only to high limit alarm (H) and low limit alarm (L). The hysteresis width can be set in the range of 0.0% (Off) to 1.0% of the recording span in 0.1 steps. The setting applies to all high limit alarms and low limit alarms. By default, the hysteresis width is set to 0.5%.

High limit alarm

Low limit alarm

Alarm occurrence

Alarm

 

value

Alarm release

Measured value

 

Alarm release

Measured

value

Hysteresis

(1% or less)

Alarm value

Alarm occurrence

<Related Topics>

Setting alarms: Section 5.2

Setting the alarm delay function: Section 7.15 and 6.10

Setting the alarm hysteresis: Section 7.1

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Omega RD100B manual Alarms Delay High Limit Alarm T, Delay Low Limit Alarm t, Alarm Hysteresis