Chapter 9 Inverter Functions
9-5-3
Constant torque characteristic (VC characteristic)
The Constant torque characteristic is suitable for applications requiring constant torque
regardless of rotational speed, such as conveyors, carts, carrier machines, and overhead crane
runs.
The constant torque characteristic has an output voltage that is proportional to the command
frequency across a straight line connecting 0 Hz/0 V with the base frequency/rated voltage.
Although the output voltage is set in proportion to the frequency from 0 Hz to the base
frequency, the output voltage from the base frequency to the maximum frequency remains
constant, regardless of the frequency.
Use the manual torque boost function to add a boost voltage to the basic proportional line. The
manual torque boost function is useful when torque is insufficient at low speeds. For details,
refer to "9.5.3 Using the Torque Boost Function".
Reduced torque characteristic (VP to the power of 1.7 characteristic)
The reduced torque characteristic is suitable for fans, pumps, and other low speed motor drive
applications that do not require a large torque.
In the low speed range, the output voltage is lowered, improving efficiency, and reduced noise
and vibration.
characteristic covers the range from 0 to 6 Hz.
Period b: The reduced torque characteristic covers the range from 10% of the
base frequency to the base frequency.
The voltage is output on a curve to the power of 1.7 in relation to the
frequency.
Period c: The voltage is a constant output characteristic from the base
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