May I know how to trigger the power alarm on the ACX7020?

We conducted a test by powering down the charger side and using a tool to measure the power current and voltage. The measured value was 17.71, but no alarm was triggered.

Could you please advise at what threshold or value the alarm will be triggered?

The operating voltage range for DC PS for the device is -24V to -60V.

https://www.juniper.net/documentation/us/en/hardware/acx7020/topics/topic-map/acx7020-power-system.html#concept_gbq_jdv_fdc

Hence ideally the device might trigger alarm when the voltage is outside this range.

This range should be checked from the CLI also, while measuring this value in meter outside box.