ISA 71.02

This standard classifies power parameters that affect industrial process measurement and control equipment. Specifications for other environmental conditions are beyond the scope of this standard.

The classes of environmental conditions stated in this standard are suitable for use in activities related to process instrumentation, including design, manufacture, sales, installation, test, use, and maintenance.

These classifications pertain only to power as received by the equipment.

The effects of power conditions on safety, comfort, and performance of operating and maintenance personnel are not considered in this standard.

Certain types of pressure regulators derive their operating power from the pressure of the controlled fluid. Similarly, certain types of temperature regulators derive pressure for valve operation from thermal expansion of the fluid in the temperature-sensing element. These self-operated and process-powered devices are not considered within the scope of this publication.

Purpose

The purpose of this standard is to establish uniform classifications of power supplied to process measurement and control equipment.

The classification system provides users and manufacturers of instruments with a means of specifying the electrical or pneumatic parameters of a power system to which a specified measurement or control system may be connected.

This document is one of a series of standards on environmental conditions for process measurement and control systems.

CAUTION: THIS DOCUMENT IS NOT INTENDED TO SERVE AS A SAFE WIRING PRACTICES MANUAL