# AutoQuiz: How to Calculate Dead Time from Transportation Delay for Thickness Control

AutoQuiz is edited by Joel Don, ISA’s social media community manager.

Today’s automation industry quiz question comes from the ISA Certified Automation Professional certification program. ISA CAP certification provides a non-biased, third-party, objective assessment and confirmation of an automation professional’s skills. The CAP exam is focused on direction, definition, design, development/application, deployment, documentation, and support of systems, software, and equipment used in control systems, manufacturing information systems, systems integration, and operational consulting. Click this link for information about the CAP program. The following question comes from the CAP study guide, Performance Domain V, Deployment.

If the distance in a sheet line from the thickness gauge to the manipulated diebolt actuators is 200 meters and the speed is 4 meters per second, then the dead time from the transportation delay for thickness control is how many seconds?

a) 200
b) 50
c) 5
d) 0.02
e) none of the above

The time it takes the sheet to go from the diebolt actuators, which are the manipulated variable, to the thickness gauge that transverses the sheet to provide the controlled variable (sheet thickness profile across the sheet), is the transportation delay. 50 seconds: Distance / velocity (200 meters / 4 meters per second) is the transportation delay.

Reference: Greg McMillan, Good Tuning: A Pocket Guide

Shares