Energy consumption reduction in case of intermittent production through the use of inverter technology: a feasibility study

Many production machines need high energy utilization due to high number of electrical devices (especially motors) used like tools, fans, pumps, actuators etc. Moreover in several industrial sectors, production phases are not continue but intermittent, with a repetition of working times and idle times. During idle times the switch off of such devices is not always possible due to technical limitations, and when it is possible, the starting phase of electrical equipments can bring, especially if very frequent, to higher unnecessary energy consumption due to peak current at the start up of the electrical motors. The purpose of this paper is to introduce the possibility to manage intermittent productions through the inverter technology. Inverters allow power control by modulate electric frequency and voltage to motors. This study, as a function of the productive parameters (number of daily stops, average duration of production stoppage, average working time, etc.) analyzes the potential energy consumption reduction at the production machines and proposes a feasibility analysis comparing the system with and without the inverter technology, considering the related investment costs and the potential energy consumption reduction. As a result the proposed analysis defines the conditions which makes this technology suitable and profitable highlighting the productive parameters and what kind of equipments bring to rapid investment payback. Moreover the proposed feasibility analysis presents an case study related to the tannery spray industry. The novelty of the study lays in the introduction of the inverter technology applied to intermittent production equipments and the definition of the set of parameters that make it profitable. The proposed research establishes a valid instrument for operations managers in order to understand if and how much is convenient to apply such technology in relation to the adopted production machines.