Simplifying The Implementation Of Machine Safety On Low Voltage Motor Control Centers

When parts of a machinery control system are required for risk reduction of a hazard, they are considered a safety function. A typical safety function is comprised of safety input and output devices which are monitored and controlled by a safety logic device. Emergency stop buttons and guard door interlocks are typical safety input devices which are often remote, and field wired. Safety relays are typical safety logic devices and safety contactors, and variable frequency drives (VFDs) are typical output devices which are commonly located inside of a Low Voltage Motor Control Center (LVMCC). Safety functions must be engineered and implemented according to relevant machinery safety standards. Despite having common design requirements, safety functions often require customized engineering when applied to a LVMCC.This paper serves as an overview of how to promote standardization in the implementation of safety functions when using LVMCC’s. Standardization reduces delivery times of safety rated LVMCC units, decreases overall cost of acquisition of a safety rated LVMCC, and enables users to maximize operational productivity while assuring a proper design of the safety function.The selection of standard safety rated motor controller units as safety function subsystems enables users to minimize personal and enterprise risk when engineering new safety functions.