Switch Loadability - IEEE Web Hosting...C37.30.1 Table C – Temperature Limitations HVS...

HVS Subcommittee Fall 2012

Switch Loadability

IEEE C37.30.1 Annex C


C37.30.1 Table C – Temperature Limitations


ACCC Designation

• Allowable Continuous Current Class • Identified on air switch nameplate • Code for composite curve of limiting switch part

classes • Majority of current air switches are DO6

• Combination of DO4 and FO6 curves • DO curve from 60°C to 25°C • O6 curve from 25°C to -30°C


Allowable Continuous Current


2000 A Switch Rating with “D06” LF Applied

Ambient (°C) LF Rating (Amps) -30 1.60 3200 -20 1.54 3080 -10 1.47 2940 0 1.41 2820 10 1.34 2680 20 1.27 2540 30 1.18 2360 40 1.08 2160 50 0.96 1920


Emergency Ratings


2000 A Switch Rating with “D06” LE1 Applied

Ambient (°C) LE1 (24 hr) Rating (Amps) -30 1.71 3420 -20 1.65 3300 -10 1.60 3200 0 1.54 3080 10 1.47 2940 20 1.41 2820 30 1.34 2680 40 1.27 2540 50 1.18 2360


2000 A Switch Rating with LE2 Applied

Ambient (°C) LE2 Rating (Amps) -30 1.65 3200 -20 1.60 3300 -10 1.54 3080 0 1.47 2940 10 1.41 2820 20 1.34 2680 30 1.27 2540 40 1.18 2360 50 1.08 2160


User Information and Precautions

• LF ≥ 1.0 only on new or properly maintained equipment • LF ≤ 2.0 regardless of the ambient temperature • Consult switch manufacturer if ACCC designation is not

known • IEEE C37.30-1962 or earlier switches

• ACCC = AO1 for non-enclosed switches • ACCC = NO1 for enclosed switches

• Switch inspection is recommended after severe emergency overload

Switch Loadability - IEEE Web Hosting...C37.30.1 Table C – Temperature Limitations HVS...

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