Drives With Quadratic Load Torque - Siemens SINAMICS G130 Engineering Manual

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1 Torque proportional to the square of speed / power proportional to the cube of speed
(work by gas or liquid friction)
This characteristic applies, for example, to fans, centrifugal pumps, reciprocating pumps which deliver into
open piping, marine drives, machines with centrifugal action.
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2 Torque proportional to speed / power proportional to the square of speed
(work by deformation)
This characteristic applies, for example, to calenders, rollers and wire-drawing machines.
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3 Torque virtually constant / power proportional to speed
(work by compression, sliding and rolling friction, hoisting against force of gravity, cutting)
This characteristic applies, for example, to piston and worm compressors working against constant pressure,
extruders, mixers, grinders, conveyor belts, conveyor systems for sheet metal / paper / foil, winches, hoisting
and traversing gear, and machine tools with constant cutting force.
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4 Torque inversely proportional to speed / power constant
(work by winding, tensile force and tensile velocity constant)
This characteristic applies, for example, to coilers, turning machines and veneer lathes.
The two drive constellations most commonly employed in practice are assessed below:
·
Drives with a torque proportional to the sqare of speed: M
and
·
Drives with a torque virtually constant: M
The basic procedure and relevant boundary conditions for both drive constellations will be explained.
Selection of suitable converters and motors for specific applications is supported by the "SIZER for Siemens Drives"
configuring tool.
10.2

Drives with quadratic load torque

Drives for fans and centrifugal pumps are typical examples of drives with a quadratic load torque M
require full torque at rated speed. High starting torques or peak loads are not a typical feature of these drives. As a
result, the converter requires only very minimal overload capability or none at all.
Drive with quadratic load torque M
= const.
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SINAMICS Engineering Manual – November 2015
Drive Dimensioning
Engineering Information
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