Table of Contents

1. Purpose
2. Established Interfaces
3. References
4. Attachments

1. Purpose

This guide is intended to give a description how to organize the interface with the Electrical group on projects. This guide shall be read with reference 3.1.

2. Established Interfaces

A list detailing interfaces is Attachment 2.

2.1 Power Supplies

The following information and requirements shall be communicated to the Electrical group:

• voltage and type of power supply required e.g. D. C., single or three-phase AC;
• number of circuits required (including spare capacity);
• uninterruptable; normal/alternate mains etc.;
• length of time that the supply is required in the event of a failure mains;
• duration of changeover from mains to standby ( e. g. 50 m. s. ) ;
• voltage regulation and tolerance;
• distribution boards requirements (presentation in the form of a “key-one line” diagram is preferred);
• required power in watts;
• allowable voltage drop;
• type of protection (fuse, automatic breaker etc.).

2.2 Alarm Systems

Full details of alarm may be provided on a form as shown on Attachment 1.

2.3 Measurement Systems

Details required may be provided by using the form as shown on Attachment 1.

Meaurements shall preferably be presented by the Electrical group as isolated analogue signals of 4-20 mA.

2.4 Electric Control Systems

All process signals shall be routed into the instrumentation system (also those with no instrumentation involvement) and then those signals for electrical control passed on to the Motor Control Center.

Detailed information could be provided on a form as shown on Attachment 1.

2.5 Control and Interface Panels

Interposing cabinets can be located in instrument rooms or electrical rooms depending on project/client requirements.If mounted in electrical rooms the Electrical group is responsible for design and requisitioning. If mounted in instrument rooms the Control Systems group is responsible for design and requisitioning.

If no interposing cabinet is used and instrument cables are routed into motor control cabinets (e.g. for start/stop) provisions should be provided inside these cabinets for mounting these cables.

2.6 Communication Systems

Where free-issue telephone handsets, radio microphone/loudspeakers closed circuit T.V. system etc. are to be incorporated in panels or desks details and space requirements are to be obtained from the Electrical group.

2.7 Cable Routing

A study drawing shall be prepared by each group clearly indicating the following:

• trench routes, including termination points of runs, space requirements including spare capacity, minimum installation depth;
• road crossings where applicable;
• segregation required between instrument cables and between instrument and electrical cables;
• details of any instrument cables to be routed in electrical cable trenches;
• fireproofing requirements where applicable.

Close coordination between the groups is mandatory to avoid duplication and to come to a sound design. Coordination with the Under Ground group for trenches and crossings will be done by the Electrical group.

2.8 Earthing

A philosophy drawing shall be prepared indicating:

• method of termination;
• application of chokes;
• earth electrode resistance requirement for each system;
• segregation between systems where applicable;
• earthing of field instruments;
• earthing systems in control rooms and equipment rooms.

3. References

3.1 Document

4. Attachments

1. Electrical Control, Alarm and Measurement Function Requirements. Available in pdf

2. CHECKLIST

Internal Procedure Control Systems/Electrical

This list will be helpful when discussing and agreeing split of work and responsibility as a unique job procedure between the Electrical and the Control Systems Design Section.