8/5/2023 7:40 PM | |
Joined: 6/11/2018 Last visit: 9/25/2024 Posts: 3 Rating: (0) |
Background: I have an old centrifugal motor pump (for big pool filtration) which works good but I am considering of buying a SINAMICS V20 to drive it for electrical cost-saving and efficiency purposes (will switch my home soon to only solar power + batteries). My question will be about if and how I need to protect this old motor against insulation stress by using it with a VFD. Motor has the following properties according to plate:
I was thinking of buying the SINAMICS V20 Single Phase Input / 3-phase Output 6SL3210-5BB23-0UV1 rated for 13.6 Amps and 3 kW. Price is around 320 Euros. For info, cable length between VFD and motor is around max 5 meters if not less. With all this, do I even need to protect the motor at all? If yes what would be my options to protect it against insulator stress, since I don't know if it is fit for a VFD?
For options 2, 3 and 4 I spent some time reading this Industry Mall link but was not able to deduce which one I would need. Additionally, in terms of budget, could you tell me which one the last three options is more or less economical? Ideally I would be ready to spend not much more than 50% to 100% the price of the VFD. Thanks in advance for your tips.
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Last edited by: mm2021 at: 08/05/2023 19:46:53 |
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8/7/2023 2:25 PM | |
Joined: 7/7/2010 Last visit: 12/5/2024 Posts: 15466 Rating: (2453) |
Just tossing out an idea on how to save costs. Purchase a replacement inverter duty motor and be done with it. For that size motor, adding the proper output filtering to protect the non-inverter duty motor that's been in use for some time will cost more (most likely) than the proper motor designed for use with VFDs.
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science guy |
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8/7/2023 7:01 PM | |
Joined: 7/7/2010 Last visit: 12/5/2024 Posts: 15466 Rating: (2453) |
You can try a sine wave filter at the output of the VFD to help smooth out the spikes. Yes since VFD output voltage spikes can easily reach (√2/2xVACrms) = 325VDC (PWM voltage from the VFD's DC bus). If the winding resistance is rated for 325V, you should be ok - for the windings. Be aware, the motor bearings may need attention as well. You might want to install a bearing grounding kit meant for motors connected to VFDs. It helps prevent bearing spalling from the spiking voltages output from VFDs (see highlighted link for more details).
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science guy |
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8/7/2023 9:18 PM | |
Joined: 6/11/2018 Last visit: 9/25/2024 Posts: 3 Rating: (0) |
I would assume that the rewinding specialist used wire rated at least for 380V (probably, since I guess he would not bother to switch wires when rewinding 230V or 380V motors?). On the other hand I totally forgot about the bearings issue indeed. For the sine wave filter I think is way too expensive; will think about the bearing grounding kit though. Regarding a new motor, I was blinded by looking only at the SIMOTICS GP line and its prices, when actually the FL line should cover my needs and is much more affordable (I see no difference between the two lines except for the fact that on the FL you get lower lead times at the expense of lack of fine customization, am I right?). So maybe the idea of buying a new one is not that bad anymore . Many thanks again for your advice.
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