AVELLY | Torque Loads

Instrument Brake Torque Loads

Overview

An Instrument Brake (IB) is an optional accessory for the 3320 series of Servo Motor Analyzers that allows a motor to be tested while driving a load. When testing using an IB, the analyzer can generate torque vs. velocity plots to validate motor performance under real-world conditions.

Plots of the motor's torque constant as a function of motor current can also be generated. Many details of a motor's performance can be quickly determined from these plots. They also serve as a useful diagnostic tool for failed motors and for design validation.

Application: B135 shown w/optional F1200 test fixture

Features

• Available in 3 torque load capacities

• Integrated 500 line encoder

• Fully calibrated for precise torque

• Plug-and-play - automatically recognized by analyzer

• Usable as a velocity feedback source

• Usable as a commutation source

• Built-in temperature sensor

• Rugged design - no delicate strain gauges to overstress

• Compatible with the optional F1200 Test Fixture

• Two year limited warranty

Calibrated Torque

Torque control is open-loop, so Instrument Brakes are easy to use and there are no sensitive strain gauges to worry about over-stressing.

Over 120 calibration datapoints are stored electronically right in the IB, so there are no calibration values that need to be entered into the analyzer by hand. For increased torque accuracy over the full velocity range, the IB is calibrated at two disparate velocities and a velocity compensation technique is employed to minimize the error due to viscous damping. When an IB is plugged into a 3320 series Servo Motor Analyzer, the analyzer automatically recognizes the IB and configures itself according to the brake's specifications.

The full torque output range is available starting at zero velocity (static rotor, see note 1 below). The amount of torque available at higher speeds is determined by the power dissipation rating of the IB in use. See the specification table below.

Power Limiting

When used with a 3320 Servo Motor Analyzer, the Instrument Brake's power dissipation is automatically limited to within safe levels. Testing is aborted by the analyzer if the brake's temperature or power dissipation exceeds the specified limits.

Velocity & Commutation Feedback

The Instrument Brake's built-in encoder significantly expands the testability of motors that are not equipped with feedback sensors. By coupling a sensorless brushless DC motor to an IB, for example, a 3320 Servo Motor Analyzer can be configured to use the IB's encoder for both commutation feedback and velocity feedback.

Application example: B135 shown w/optional F1200 test fixture

Specifications

Model	Torque [oz·in]	Min Velocity [RPM] (Note 1)	Max Velocity [RPM]	Max Continuous Power [W] (Note 2)	Accuracy [% full scale]	Shaft Diameter [in]
B111	0.4 - 11	5	9,000	9	±2	0.1873
B135	0.7 - 35	5	8,000	15	±1.5	0.2497
B185	3.0 - 85	5	6,000	35	±1.2	0.3745

Note 1:	The IB output torque is available down to zero RPM. However, the output torque may not fall within the specified accuracy when operating at speeds lower than the specified minimum velocity.
Note 2:	Power dissipation may exceed this limit for short periods of time. The Servo Motor Analyzer will ensure that neither the average power dissipation nor the operating temperature limit is exceeded.
Note 3:	Yearly factory re-calibration is recommended.

Ordering Information

31-402-2
B111 11oz·in Instrument Brake

31-402-3 B135 35oz·in Instrument Brake

31-402-4 B185 85oz·in Instrument Brake