4 v/f patterns [p tj, 4 v/f patterns [p, P tj – Toshiba VF-SX User Manual

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9-8

TOSHIBA

9.1.4

V/f Patterns

[P tj

The V/f characteristic may be set for constant torque loads, resulting in a

linear relationship between output voltage and frequency. There is a separate
setting for variable torque loads which sometimes results in energy savings, if

the application is suitable for this V/f pattern. Fans and centrifugal pumps are

the most common types of loads associated with the variable torque load V/f

pattern. See Figures 9.4 and 9.5.

TABLE 9-3: SELECTION OF CONSTANT OR VARIABLE TORQUE V/f PATTERNS

1 [P t]

Value

Function

For constant torque characteristics.

For variable torque characteristics (Energy saving

operation is possible. Motor noise may also be

decreased.)

Pt-0:

Constant

Torque

Characteristics

fc - / : Variable Torque

Characteristics

Output

Voltage

Output

Voltage

Figure 9.4 Constant Torque

V/f Curve

Figure 9.5 Variable Torque

V/f Curve