The most important characteristic of any measurement instrument is repeatability and accuracy. The Magtrol Dial Weight Dynamometer uses the combination of a Hysteresis Brake and gravity to insure constant, reliable results. The brake torque rise is directly proportional to applied current. The calibrated weight system provides readings in standard engineering units through the use of multiple torque range scales provided on each size dynamometer.
Magtrol Dial Weight Dynamometers are a lower cost alternative to our standard (load cell) Hysteresis Dynamometers. The dial weight dynamometers are easy to operate, provide repeatable and accurate results, and will operate for many years with minimal maintenance. A Magtrol Dial Weight Dynamometer System can only operate manually in an open loop mode.
Specifications and Drawings
|Model||Full Scale Torque (Range One)||Full Scale Torque (Range Two)||Full Scale Torque (Range Three)||Maximum Operating Speed (RPM)||Power Ratings - 5 Minutes (Watts)||Power Ratings - Continuous (Watts)||Downloads|
|HD-106-1||0.5 oz·in||1 oz·in||2 oz·in||30,000||35||7||pdf | step|
|HD-400-1||2 oz·in||8 oz·in||16 oz·in||20,000||200||55||pdf | step|
|HD-400-2||8 oz·in||16 oz·in||32 oz·in||20,000||200||55||N/A|
|HD-500-1||25 oz·in||50 oz·in||100 oz·in||15,000||400||80||step|
|HD-600-1||50 oz·in||100 oz·in||200 oz·in||10,000||600||100||pdf|
|HD-700-1||100 oz·in||200 oz·in||400 oz·in||10,000||700||150||pdf|
|HD-705-1||200 oz·in||400 oz·in||800 oz·in||8,000||1400||300||pdf|
All dynamometer models are within 1% accuracy, with the exception of the following:
|HD-106-1||0.5 oz·in range is 3.5%|
|HD-106-1||1.0 oz·in range is 2%|
|HD-400-1||2.0 oz·in range is 2%|
|HD-400-1||8 oz·in range is 2%|
|HD-400-2||8 oz·in range is 2%|
|HD-500-1||25 oz·in range is 2%|
Magtrol Dynamometers cover a wide range of Torque, Speed and Mechanical Power ratings. To select the appropriate size Dynamometer for your motor testing needs, you will need to determine the Maximum Torque, Speed and Power applied to the Dynamometer:
It is important to consider all torque points that are to be tested, not only rated torque, but also Locked Rotor and Breakdown Torque. Dynamometer selection should initially be based on the maximum torque requirement, subject to determining the maximum power requirements.
This rating is to be considered independent of torque and power requirements, and is the maximum speed at which the Dynamometer can be safely run under free run or lightly loaded conditions. It is not to be considered as the maximum speed at which full braking torque can be applied.
Maximum Power Ratings
These ratings represent the maximum capability of the Dynamometer Braking System to absorb and dissipate heat generated when applying a braking load to the motor under test. The power absorbed and the heat generated by the Dynamometer is a function of the Torque (T) applied to the motor under test, and the resulting speed (n) of the motor. This is expressed in these power (P) formulas:
|SI:||P (watts)||=||T (N·m)||x||n (rpm)||x||(1.047 × 10-1)|
|English:||P (watts)||=||T (lb·in)||x||n (rpm)||x||(1.183 × 10-2)|
|Metric:||P (watts)||=||T (kg·cm)||x||n (rpm)||x||(1.027 × 10-2)|
|All of Magtrol's controllers, readouts and software calculate horsepower|
as defined by 1 hp = 550 lb·ft / s. Using this definition:
|To calculate power, use Magtrol's online motor power calculator|
The Dynamometer’s ability to dissipate heat is a function of how long a load will be applied. For this reason, the Maximum Power ratings given are based on continuous operation under load, as well as a maximum of 5 minutes under load.
To safely dissipate heat and avoid Dynamometer failure, the maximum power rating
is the most important consideration in selecting a Dynamometer.