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17th Nov 2021, 01:20 PM #1New Member
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Motor conversion Hercus 9inch AR 1970s
Hi, I have just acquired a Hercus 9" AR model, built around 1970s (#13250).
I want to (if possible) convert the 3phase motor to use with VFD, so single phase (domestic) -> VFD -> 3phase motor
I'm a complete inept at electrical stuff...
A few questions regarding the motor (original), which is .5hp, 3phase, unknown voltage (as that part of engraving/plate is not legible):
- Is the original motor 240v or 415v?
- Given the picture of the junction box (or whatever you call it), does this require star -> delta conversion? or is it just impossible to be used with VFD?
Screen Shot 2021-11-17 at 12.17.58 pm.png
- Someone said that if the motor is a 3-phase 240v, all I need is a matching VFD (i.e. .5hp rated VFD) and there should be no loss in power, however if motor is 3-phase 415v, i need to double the VFD to 1hp, is this correct?
- What is the best way forward to get the motor going? I believe the original motor still works as the guy that sold to me said so; or is it better to just get one of those new motor + VFD packages from ebay?
Cheers
David.
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17th Nov 2021, 01:40 PM #2Member: Blue and white apron brigade
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These Hercus motors are 415V "STAR" connected and need to be doctored internally to be converted to "DELTA" to be able to run on 240V 3Phase, as provided by a 240V single phase VFD.
OR
You can use an Ecogoo VFD which converted 240V single phase direct to 415V 3 phase and no motor mod is needed.
Do a search for Ecogoo VFD in these forums and you will see them discussed in some detail.
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17th Nov 2021, 02:22 PM #3New Member
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17th Nov 2021, 02:30 PM #4Member: Blue and white apron brigade
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I believe it is possible set a current limit on the Ecogoo VFD - the 750W Ecogoo VFD probably uses a current limit of ~4A , so for the 375W motor I would limit that to say 2.5 or 3A and you should be OK. Someone with an Ecogoo will hopefully pipe up and answer this question.
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