What is the state of the relay alarm?

What is the status of the relay alarm? Here's to understand:

In general, alarms and interlocks of instruments, DCS, and frequency converters are indispensable to the use of relays, that is, alarms and interlocks are mostly connected through relay contacts and alarms and interlocking circuits. Is the relay coil energized or in a de-energized state when alarming? From the perspective of reliability, we analyze the advantages and disadvantages of live and lost power.

The relay coil is energized and operates to make the circuit alarm. This is the most easily understood design, but there is a hidden danger, that is, when the relevant wiring is not connected and an open circuit occurs, or if the relay coil power supply has a problem, an accident needs to be alarmed. The relay coil should be energized and operated, but due to the above-mentioned reasons, it will not operate and make mistakes. This result is very serious.

If the alarm is changed to power off, if the instrument wiring is not connected or open circuit, the relay coil power supply problem, or the instrument failure, there will be no possibility of misstatement. The reason is that in the absence of alarm, the relay coil is in a live state. Once the above-mentioned abnormal phenomenon occurs, the relay coil will return to the de-energized state. The operation and maintenance personnel will find the cause of the alarm because of the alarm. When the signal is found to be normal. When the alarm occurs, it will search for other reasons and eliminate the fault, so that the alarm circuit will return to normal, so as to avoid the occurrence of a missing message. Obviously, the power-off alarm is more reliable than the live alarm.