Often, we at the George T. Hall Company are called out to a facility to upgrade and retrofit an existing, outdated control system. Many of these systems are either outdated PLC’s or the facility is utilizing an electromechanical control relay approach. Often this system has worked effectively for quite a number of years but today's PLC based control systems offer a more efficient and cost effective approach. A control system design is a balance between costs and reliability.
Application considerations include:
- How many I/O points are there?
- What are the voltage and current requirements for the devices being controlled or supplying input (field I/O)?
- How reactive are the field devices (inductive/capacitive properties)?
- How often are the field I/O’s changing state?
- Is maintenance a concern?
For a reliable system, the designer must understand the properties of the field I/O. Both PLCs and electromechanical relays are concerned with reactive loads in regards to the reliability of the system. Asking these questions and others to offer the customer the most balanced and technologically advanced control system available to best fit the application, is where the engineers at GTH excels. Read the full article on article on Control Engineering!