When performing designs where mixed standards are used, there will be lots of confusions along the process. These confusions will one way or another affect the result of the project in terms of delivery time, quality and costs. Most of the larger projects have these standards in-placed, smaller projects tend to be more relaxed with respect to the use of mixed standards.

A good example of the use of mixed standard was an offshore project in Bohai Bay near Beijing, China. The existing offshore platforms was constructed, owned and operated by an American company. The standards used were all North American Standards. After decades of operation, the offshore platform requires expansion. The new platforms will be constructed based on Chinese standards which are basically IEC standards modified to suit local environment and regulations. The existing electrical equipment and cables are all ANSI/IEEE standards. The new electrical equipment and cables will be IEC to comply with the current Chinese standard. To tie-in the existing and new equipment became very difficult. The rest is history.

In a mixed standards project, understanding the terminologies is essential. Below is a list of the most commonly used terms.

Terminology - comparison of IEC and ANSI terms
Earth Ground
Single line diagram One-line diagram
Power (kilowatts) Horsepower
Direct-on line (DOL) across-the-line
Lightning rod Air terminal
star wye
Voltage regulation Voltage spread
High voltage (>1,000 V) per AS/NZS 3000 Medium voltage (>1,000V – 100,000 V)
Current rating Ampacity
Short circuit interrupting capacity Interrupting rating
Short circuit making capacity Momentary current rating
Short time withstand current Short circuit rating
Diversity factor Demand factor
Utilisation factor (Duty) Run factor
Maximum demand Peak load
Essential load Stand-by load
Ring main Primary loop
Running Continuous
Natural cooled self-cooled
Prefabricated switchroom Power house

To see more terminologies, refer to IEC 60050 Vocabulary and the ANSI/IEEE Std 100 - The IEEE Standard Dictionary of Electrical and Electronics Terms.


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