I wanted to build a device to test DC motors and get accurate measurements for inductance capacitance and resistance so similar to and RLC meter but also be able to test other parameters
for example I have information on a dc motor but would like to make a device to test the motor and obtain measurements (Highlighted by multiple ????????)
Nominal Voltage 12V
No Load Speed 12500RPM
Stall Torque 3.24mNm????????
Speed/Torque Gradient -3930rpm/nNm
No Load Current 5.67mA
Starting Current 360mA
Terminal Resistance 33.3 Ohms?????????
Max Permissible Speed 19000rpm
Max Continuous Current 177mA
Max Continuous Torque 1.59mNm
Max Power Output at Noiminal Voltage 1050mW ?????????
Torque Constant 9.00mNm/A
Terminal Inductsnce 0.30mH??????????
Gear Reduction Ratio 16:01
maximum mechanical efficiency 81%
maximum output torque 30mHM
backlash no load <2degrees
I am open to ideas or methods of how to go about this or if it is impossible please let me know why.
In order to build a single device to do all those tests, you need to build each test individually to work out all the bugs in the design.
Are you asking how to build each test device or are you asking how to combine all the test sets into a single device?
How far along are your individual test sets?
Sounds like a fun project, but it’s also quite complex. Follow @Paul_KD7HB’s suggestions, they’re a great starting point. Some of the tests you’ll need to conduct may require a dynamometer. Are you planning to build one?
Additionally, what are the specifications for your test stand (your tester)? For example, what are the minimum and maximum motor sizes it will need to handle? Providing these details will help refine the design and approach for your project.
Thank you for your time, I would like to make one device to measure / calculate the parameters I have highlighted above.
What I am asking is for help on how to approach torque measurements. In my previous jobs I believe toque was measured by using another motor (Dyno ) and providing a resistance to the motor on test.
to get measurements for the inductance capacitance and resistance I was going to apply a sine wave at varies different frequencies and measure the current and voltage and from them measurements i should be able to work out the impedance/characteristics of the motor.
I also have know idea how one would go about to measure backlash accurately.
There is a pieace of equipment we have and it has over 300 small maxon dc motors which are all the same but seem to fail frequently. they have inbuil gear box and encoder.
It was basically to help identify were these motors are failing, hence i am looking for a way to test motor.
I would suspect brushes and commutator, the weakest parts of a brushed DC motor, followed by bearings. Most small motors don't have replaceable brushes and bearings.
I once built a dyno for fractional horsepower motors from two rings cut from a 10 inch steel pipe, 8 cam rollers and a fish scale.
I'm not able to draw diagrams anymore but I could describe it in a PM if you would like.
These sound like inexpensive hobby motors. I put the following guidelines in place this in a factory where we had a lot of DC motors, ranging from fractional to several hundred horse power the following guidelines:
Monitor Symptoms of Worn Brushes
Sparking: Increased sparking at the commutator may indicate worn brushes.
Noise: Unusual noise or a change in the motor's sound might signal brush wear.
Performance Issues: Decreased torque, irregular speed, or increased vibration may indicate brush problems.
Measure Current Draw
Use a clamp meter to monitor the motor’s current draw.
Worn brushes can cause erratic or increased current draw due to poor contact.
Measure Voltage Drop
Measure the voltage drop across the brushes while the motor is running.
Excessive drop may indicate poor contact due to wear.
Observe Maintenance Indicators
Some motors have visual inspection ports or external indicators showing brush wear.
Others have wear marks or indicators on the brushes themselves that signal when replacement is needed.
Use Predictive Maintenance Tools
Thermal Imaging:
Use a thermal camera to detect hot spots at the brush or commutator area, which may indicate excessive friction or poor contact.
Vibration Analysis:
Analyze vibrations with a sensor. Changes in vibration patterns may correlate with worn brushes.
6.Scheduled Inspections
If your motor can’t be stopped, review operational hours against the manufacturer’s brush life expectancy. Manufacturers often provide estimated brush life in hours based on usage and load.
7.Advanced Monitoring Systems
Some motors are equipped with sensors or systems to monitor brush wear in real-time, providing alerts when replacement is needed.
Important Safety Note
Avoid touching or attempting physical inspection of brushes while the motor is running, as this can be hazardous. Plan a shutdown for a thorough inspection if the above methods indicate a problem.
Use this list as a starting point for your maintenance plan. Additionally, consider implementing a periodic replacement schedule for all motors. While it may seem costly upfront, it could be less expensive in the long run compared to the downtime and expenses incurred when motors fail unexpectedly.