Glossary · HMI, SCADA and operations
Alarm
Also known as: Process alarm
German: Alarm
In alarm management according to ANSI/ISA-18.2 and IEC 62682, an alarm is an audible and/or visible means of indicating to the operator an equipment malfunction, process deviation or abnormal condition that requires a timely response.
- HMI and SCADA
- Process industry
In one sentence
An alarm tells the operator about a malfunction, deviation or abnormal condition that requires a timely response.
Example
When the level in a storage tank exceeds 90 percent, the HMI sounds a horn and shows a high-priority alarm telling the operator to stop the transfer pump.
How it applies
- Engineering: Every alarm should have a defined operator action, a priority, a cause and consequence. Conditions that need no response are events or status messages, not alarms. Alarm limits and priorities come from Alarm rationalization.
- Operation: Too many alarms or alarms without action erode trust and lead to Alarm flooding.
- Documentation: The alarm response manual or alarm help text states the cause, the consequence and the operator action for each alarm. Keep HMI texts, help texts and the master alarm database consistent.
Alarm vs. warning message
An HMI alarm is a process indication requiring timely operator response. A Warning message in safety information warns people of a hazard and how to avoid it. An HMI alarm is not a substitute for safety information in the instructions, and neither replaces protective measures.