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Glossary of terms – Rockwell Automation 7000 PowerFlex Medium Voltage (B Frame) Commissioning - ForGe (PanelView 550) User Manual

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122

Rockwell Automation Publication 7000-IN006B-EN-P - May 2013

Appendix A

General Reference

Table 10 - PowerFlex 7000 Drive Torque Capabilities

** Drive will require over sizing to achieve greater than 100% continuous torque.

Glossary of Terms

Breakaway Torque: Torque required to start a machine from standstill.

Accelerating Torque: Torque required to accelerate a load to a given speed, in a
certain period of time. The following formula may be used to calculate the
average torque to accelerate a known inertia (WK

2):

T = (WK

2 x change in RPM) / 308t

where:

T = acceleration torque in N.m (lb.-ft.)
W = force N or kg f (lb)
K = gyration radius m (ft)
WK2 = total system inertia (kg f x m2 [lb-ft2

]

) that the motor must

accelerate, including motor, gear box, and load

t = time (seconds) to accelerate total system load

Steady State Torque: Continuous operating torque required to control the load,
without instability.

Torque Limit: An electronic method of limiting the maximum torque available
from the motor. The software in a drive typically sets the torque limit to 150% of
motor rated torque.

Table 11 - Typical Application Load Torque Profiles

Parameter

7000 Torque Capability Without
Tachometer (% of Motor Rated
Torque)

7000 Torque Capability With
Tachometer
(% of Motor Rated Torque)

Breakaway Torque

90%

150%

Accelerating Torque

90% (0-8 Hertz)

140% (0-8 Hertz)

125% (9-75 Hertz)

140% (9-75 Hertz)

Steady State Torque

125% (9-75 Hertz) **

100% (1-2 Hertz)

140% (3-60 Hertz) **

Maximum Torque Limit

150%

150%

Application

Load

Torque
Profile

Load Torque as Percent of Full-Load Drive Torque

Required Drive

Service Duty

Rating

Tachometer

Required for

Extra Starting

Torque?

Break-away

Accelerating

Peak Running

AGITATORS

Liquid CT

100

100

100

Heavy

Yes

Slurry

CT

150

100

100

Heavy

Yes

BLOWERS (centrifugal)

Damper closed

VT

30

50

40

Normal

No