App. B Japanese Guideline for Suppressing Harmonics by Customers Receiving High Voltage or Special High Voltage
A-15
App.
(2) Calculation of harmonic current
Usually, calculate the harmonic current according to the Sub-table 3 "Three-phase bridge rectifier with the
smoothing capacitor" in Table 2 of the Guideline's Appendix. Table B-5 lists the contents of the Sub-table 3.
Table B-5 Generated Harmonic Current (%), 3-phase Bridge Rectifier (Capacitor Smoothing)
Degree 5th 7th 11th 13th 17th 19th 23rd 25th
w/o a reactor 65 41 8.5 7.7 4.3 3.1 2.6 1.8
w/ a reactor (ACR) 38 14.5 7.4 3.4 3.2 1.9 1.7 1.3
w/ a reactor (DCR) 30 13 8.4 5.0 4.7 3.2 3.0 2.2
w/ reactors (ACR and DCR) 28 9.1 7.2 4.1 3.2 2.4 1.6 1.4
• AC reactor: 3%
• DC reactor: Accumulated energy equal to 0.08 to 0.15 ms (100% load conversion)
• Smoothing capacitor: Accumulated energy equal to 15 to 30 ms (100% load conversion)
• Load: 100%
n th generated
harmonic current (%)
n th harmonic current (A) = Fundamental current (A) ±
100
calculate the harmonic current of each degree using the following equation.
(3) Maximum availability factor
• For a load for elevators, which provides intermittent operation, or a load with a sufficient designed motor
rating, reduce the current by multiplying the equation by the "maximum availability factor" of the load.
• The "maximum availability factor of an appliance" means the ratio of the capacity of the harmonic
generator in operation at which the availability reaches the maximum, to its total capacity, and the
capacity of the generator in operation is an average for 30 minutes.
• In general, the maximum availability factor is calculated according to this definition, but the standard
values shown in Table B-6 are recommended for inverters for building equipment.
Table B-6 Availability Factors of Inverters, etc. for Building Equipment (Standard Values)
Equipment type
Inverter capacity
category
Single inverter
availability
200 kW or below 0.55 Air conditioning
system
Over 200 kW 0.60
Sanitary pump ― 0.30
Elevator ― 0.25
Refrigerator,
freezer
50 kW or below 0.60
UPS (6-pulse) 200 kVA 0.60
Correction coefficient according to contract demand level
Since the total availability factor decreases if the scale of a building increases, calculating reduced
harmonics with the correction coefficient defined in Table B-7 is permitted.
Table B-7 Correction Coefficient according to the Building Scale
Contract demand (kW) Correction coefficient β
300 1.00
500 0.90
1,000 0.85
2,000 0.80
Note: If the contract demand is between two specified values listed in Table B-7, calculate the value by
interpolation.
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