Comparison of the reliability of programmable logic controller and electromagnetic relay control in industrial production line

Abstract

This paper is aimed at determining the reliability of Industrial Production Line using Programmable Logic Controller. Production lines in the manufacturing sector are automated using Programmable Logic Controller module, which is programmed using programming software. The programming software used is the Siemens S7-200 while the programming language is the Ladder Programming language. Most manufacturing industries in Nigeria today still use relays for control purposes. The wirings from the control panel are so massive that any fault from the machine usually takes hours to trace and replace using the traditional electromagnetic relay. Alternative and better control methods use Programmable Logic Controller. Research articles on the reliability of PLC in a food production line are scarce. This paper is written to address this gap. The study uses the statistical analytical method, which provides useful and higher accuracy of the result as it allows high tolerance to uncertainties. The study determines the failure rate, the mean time between failures (MTBF), mean time to failure (MTTF), and availability as a means of determining the reliability of the network. Accordingly, the study showed that the mean availability of the Production line using PLC for three consecutive years is 84% while the reliability is 86%. Consequently, the use of PLC should be encouraged in industrial automation as the fault can be detected easily, thereby reducing downtime as compared to the use of electromagnetic relay in the control circuitry.

Keywords: Programmable logic controller, availability, reliability, ladder programming language, relay logic