The beeping from a Kidde alarm may mean it is detecting smoke, the battery is dying or the unit needs to be cleaned. The different sounds the alarm makes can help determine the cause.
A steady alarm is a sign that there is smoke in the air. It will not stop until the smoke is cleared. Beeping every 30 seconds could mean that the battery needs to be replaced or the alarm is dying. If the alarm just goes off sporadically, the battery may not be installed properly. If the humidity is too high, the alarm may also go off occasionally.