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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. This question is from the CAP study guide, Performance Domain IV, Development.

The average person cannot respond to signals more frequent than one every:

a) 30 milliseconds
b) 80 milliseconds
c) 300 milliseconds
d) 800 milliseconds
e) none of the above

The average person cannot process signals more frequent than one every 300 milliseconds, or about three signals per second. Therefore, for reliable regulation of events that are faster than three signals per second, a person should not act as the controller.

The correct answer is C, 300 milliseconds.

Reference: Donald A. Coggan, Fundamentals of Industrial Control: Practical Guides for Measurement and Control, Second Edition.