Every alarm is associated with a level of severity or priority that indicates how critical or how important or even any intervention is needed. In the case of the low oil level in the hydraulic system then the intervention of the operator is needed to refill the hydraulic tank with oil as soon as possible. In the case of very low oil level then the hydraulic system is in very critical condition and hence it should be shut down to prevent any damage to the machines and to the equipments. By contrast, in the case of the end of a shift, the severity would be minimal. The severity of an alarm usually depends upon the circumstances, the factory application, the nature of the equipment, safety, availability of backup systems, potential costs of damage or downtime and so on.