Spare and Expansion Capabilities of Process Control System

This article is about specification and standards for control system projects, where how to check ”Spare and Expansion Capabilities of Process Control System”.

Introduction to Expansion and Spare Capability

Expansion and spare capacity are important aspects of any system. It ensures that the system is able to handle peak loads during upset conditions and to provide additional capacity required for configuration of spare I/O points and associated control algorithms. Additionally, it also enables the utilization of the spare I/O slots. This article will discuss the requirements for expansion capacity and spare I/O in control systems, FOUNDATION Fieldbus systems, and servers and engineering workstations.

Spare and Expansion Capabilities for Non FOUNDATION Fieldbus I/O Systems

Each system must be supplied with 5% spare I/O points for non FOUNDATION Fieldbus I/O. The spare I/O must be licensed, installed, and wired to termination points. The spare I/O should be provided in approximately the same ratio as that of the installed types and must be distributed between risk areas in the approximate ratio as the required I/O.

Where both redundant and simplex I/O models are used for a signal type, the requirement for spare I/O must apply for both types. Additionally, the system must be installed with 10% spare slots in I/O chassis or baseplates to accommodate addition of I/O modules without requiring additional chassis or baseplates to be added to the system.

Power supplies for I/O modules must be sized to accommodate the 5% installed spare and the additional 10% expansion requirement.

Spare and Expansion Capabilities for FOUNDATION Fieldbus Systems

FOUNDATION Fieldbus based systems must be supplied with 10% spare H1 segment communications modules. Segment power conditioners must be sized to accommodate an additional 20% increase in the number of devices attached to the segment.

Expanding the Number of Controllers

Each system must be capable of expanding the number of controllers by 10% from that installed in the base system. For expansion projects, the requirements for spare I/O and expansion capability must be mutually agreed upon between PMT and Proponent and specified in the project specific FSD. If none are specified in the FSD, the requirements must be as outlined in the article.

CPU Loading

The average CPU Loading of any controller during normal operating conditions must not exceed 65% overall or 75% of the manufacturers recommended maximum loading specification, whichever is lower. This requirement applies to new controllers installed in grass roots facilities and for expansion projects where additional control is being added to existing controllers.

Servers and/or Engineering Workstations

Servers and/or engineering workstations must be designed as per the vendor’s recommendations. Servers and workstations must be configured with additional spare capacity of 40% minimum for hard-drive space, memory, and CPU, or as per the vendor’s recommendations, whichever is more stringent. CPU and memory spare requirements must be verified on the running system during steady-state conditions with all applicable software running on the system.

Factory Acceptance Testing

Spare and expansion capabilities must be verified during Factory Acceptance Testing.

Conclusion

Expansion and spare capacity are essential components of control systems, FOUNDATION Fieldbus systems, and servers and engineering workstations. This article has outlined the requirements for expansion capacity and spare I/O that must be adhered to for these systems. Additionally, the requirements for spare I/O and expansion capability for expansion projects must be mutually agreed upon between PMT and Proponent and specified in the project specific FSD.