Fuji Electric frenic mini series, Руководство пользователя

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A-18
(2) Calculation of harmonic current
Usually, calculate the harmonic current according to the Sub-table 3 "Three phase bridge rectifier
with the filtering capacitor" in Table 2 of the Guideline's Appendix. The C.5 lists the contents of the
sub-table 3.
Table C.5 Generated Harmonic Current (%), 3-phase Bridge Rectifier (Capacitor Filtering)
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
- ACR: 3%
- DCR: 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%
Calculate the harmonic current of each degree using the following equation:
100
(%) current harmonic nth Generated
(A) current l Fundamenta (A) current harmonic nth
× =
(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 C.6 are recommended for inverters for building equipment.
Table C.6 Availability Factors of Inverters, etc. for Building Equipment (Standard Values)
Equipment
type
Inverter capacity
category
Single inverter
availability
200 kW or less 0.55 Air
conditioning
system
Over 200 kW 0.60
Sanitary pump ――― 0.30
Elevator ――― 0.25
Refrigerator,
freezer
50 kW or less 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
β
defined in Table C.7 is permitted.
Table C.7 Correction Coefficient according to the Building Scale
Contract demand
(kW)
Correction
coefficient
β
300 1.00
500 0.90
1000 0.85
2000 0.80