Allen-Bradley PowerFlex 70 Reference Manual

2-2 Determining Dynamic Brake Requirements
Gather the Following Information
• Power rating from motor nameplate in watts, kilowatts, or
horsepower
• Speed rating from motor nameplate in rpm or rps (radians per
second)
• Required decel time (per Figure 2.1
, t
3
– t
2
). This time is a process
requirement and must be within the capabilities of the drive
programming.
• Motor inertia and load inertia in kg-m
2
or WK
2
in lb.-ft.
2
• Gear ratio (GR) if a gear is present between the motor and load
• Motor shaft speed, torque, and power profile of the drive application
Figure 2.1 shows typical application profiles for speed, torque and
power. The examples are for cyclical application that is periodic over t
4
seconds. The following variables are defined for Figure 2.1:
ω(t) = Motor shaft speed in radians per second (rps)
N = Motor shaft speed in Revolutions Per Minute (RPM)
T(t) = Motor shaft torque in Newton-meters
1.0 lb.-ft. = 1.355818 N-m
P(t) = Motor shaft power in watts
1.0 HP = 746 watts
ω
b
= Rated angular rotational speed
ω
o
= Angular rotational speed less than ω
b
(can equal 0)
-P
b
= Motor shaft peak regenerative power in watts
ω
2πN
60
----------=
Rad
s
---------
Rad
s
---------

Allen-Bradley PowerFlex 70 Specifications

General

Input Voltage	200-240V AC, 380-480V AC, 500-600V AC
Frequency Range	0 - 400 Hz
Humidity	5% to 95% non-condensing
Output Voltage	0 to Input Voltage
Control Methods	Sensorless Vector Control
Communications	Ethernet/IP, DeviceNet, ControlNet
Protection Features	Overcurrent, Overvoltage, Undervoltage, Overtemperature, Ground Fault
Operating Temperature	0°C to 50°C (32°F to 122°F)
Storage Temperature	-40°C to 70°C (-40°F to 158°F)
Enclosure Rating	IP20, NEMA Type 1