fredUK
Mechanical
- May 13, 2009
- 10
I am looking to find a way of braking three phase vibratory motors quickly, as the motors have excessive levels of vibration on shutdown. An example spec of one of our vibratory motors is as follows:
3-phase, 0.9KW, 1.45A flc, 400V supply @ 50Hz
These vibratory motors are usually just run DOL, so deceleration may take between 5-10 seconds. During this period, the motor runs from 25Hz running vibration down to 0Hz, with resonant vibration typically occurring at 10-15Hz. It has been found that by stopping the motor in 0.5 seconds, the vibration is virtually eliminated. I am looking at a low cost solution for achieving this braking time.
Initially, I investigated DC injection brake modules as a possibility. These were found to reduce vibration, but could not achieve a quick enough stop (probably due to the delay in dc injection). I then tried inverters with ramp down and dc injection for braking. This gave improved shutdown times, but for larger motors, it was found that the inverter could not cope with the over-current. As a result, I wired a braking resistor across the inverter, to dissipate the energy as heat. This enabled me to stop the motor in 0.25 seconds and was very effective in reducing vibration. The inverter and braking resistor can cost £300-£400. Does anyone have any ideas on how to stop these motors in 0.5 seconds, but at a lower cost?
3-phase, 0.9KW, 1.45A flc, 400V supply @ 50Hz
These vibratory motors are usually just run DOL, so deceleration may take between 5-10 seconds. During this period, the motor runs from 25Hz running vibration down to 0Hz, with resonant vibration typically occurring at 10-15Hz. It has been found that by stopping the motor in 0.5 seconds, the vibration is virtually eliminated. I am looking at a low cost solution for achieving this braking time.
Initially, I investigated DC injection brake modules as a possibility. These were found to reduce vibration, but could not achieve a quick enough stop (probably due to the delay in dc injection). I then tried inverters with ramp down and dc injection for braking. This gave improved shutdown times, but for larger motors, it was found that the inverter could not cope with the over-current. As a result, I wired a braking resistor across the inverter, to dissipate the energy as heat. This enabled me to stop the motor in 0.25 seconds and was very effective in reducing vibration. The inverter and braking resistor can cost £300-£400. Does anyone have any ideas on how to stop these motors in 0.5 seconds, but at a lower cost?