GENSET SIZING — DETERMINING LOAD CHARACTERISTICS
Determining Load Characteristics (continued)
5.If reduced voltage motor starting is used, determine SkVA as in Steps 1, 2, 3, or 4 on previous page, and then multiply the value by the appropriate multiplying factor in Table 5. Use the following formula:
Calculate SkW as follows:
1.If SPF (Starting Power Factor) is unknown, refer to Table 4 on page 22 and use the value corresponding to the motor horsepower. If a
2.Multiply SkW by 0.5 for motors with low inertia loads (i.e., centrifugal fans, compressors and pumps) where starting torque requirements are low.
Table 6. Reduced Voltage Starting Methods and Characteristics
| % Full | % Full | % Full | SkVA |
| |
Starting Method | Voltage | Voltage | Multiplying | SPF | ||
Voltage kVA | ||||||
| Applied | Torque | Factor |
| ||
|
|
| ||||
Full Voltage | 100 | 100 | 100 | 1.0 | — | |
Reduced Voltage | 80 | 64 | 64 | 0.64 | — | |
65 | 42 | 42 | 0.42 | — | ||
Autotransformer | ||||||
50 | 25 | 25 | 0.25 | — | ||
| ||||||
Series Reactor | 80 | 80 | 64 | 0.80 | — | |
65 | 65 | 42 | 0.65 | — | ||
| 50 | 50 | 25 | 0.50 | — | |
Series Resistor | 80 | 80 | 64 | 0.80 | 0.60 | |
65 | 65 | 42 | 0.65 | 0.70 | ||
| 50 | 50 | 25 | 0.50 | 0.80 | |
Star Delta | 100 | 33 | 33 | 0.33 | — | |
|
|
|
|
|
| |
Part Winding (Typical) | 100 | 60 | 48 | 0.6 | — | |
Wound Rotor Motor | 100 | 160* | 100* | 1.6* | — |
*— These are percents or factors of running current, which depend on the value of the series resistances added to the rotor windings.
PAGE 24 — INDUSTRIAL GENERATOR SETS — APPLICATION & INSTALLATION MANUAL — REV. #4 (09/07/07)
