Hey guys.
I have a really good bench grinder an old one that is robust and well built as they are back in the old days haha.
The capacitor has let go. Now the grinder has no centrifugal switch so I’m assuming it needs a motor "run" capacitor NOT a start up capacitor as it has no centrifugal switch so I guess the capacitor is in circuit all the time. I found this cap in my draws and my question is: is this the type I need? And how do I know?
The photo is the one on the left is the old one and the right is the new one I have.
I just want to make sure as 240v can be lethal plus an exploding cap is definitely not what you need!!!
Cheers
I have a really good bench grinder an old one that is robust and well built as they are back in the old days haha.
The capacitor has let go. Now the grinder has no centrifugal switch so I’m assuming it needs a motor "run" capacitor NOT a start up capacitor as it has no centrifugal switch so I guess the capacitor is in circuit all the time. I found this cap in my draws and my question is: is this the type I need? And how do I know?
The photo is the one on the left is the old one and the right is the new one I have.
I just want to make sure as 240v can be lethal plus an exploding cap is definitely not what you need!!!
Cheers
sweet yeh I think the extra uf will change torque slightly but that shouldn't matter much. So it's suitable for a motor without a centrifugal switch? so it can be in circuit all the time with 240v on it continuously?The new capacitor is almost certainly a metal film capacitor. It will work but is not really designed to handle current. This will cause it to fail quickly. You should get a higher current foil and film motor run capacitor intended for higher horsepower motors. The type you show is often used with very small motors and still fails in use.
400 VDC is only about 125 VAC. (Note both capacitors shown have AC ratings. The newer one is rated for voltage only, not power! The old one should be able to handle more than 1.5 amps.)
Been there done that.
Just for grins, after it fails you can take it apart and unwind it. There will be a nice line the length of the film where the metal layer has burned off. That does not usually happen with metal foil units.
400 VDC is only about 125 VAC. (Note both capacitors shown have AC ratings. The newer one is rated for voltage only, not power! The old one should be able to handle more than 1.5 amps.)
Been there done that.
Just for grins, after it fails you can take it apart and unwind it. There will be a nice line the length of the film where the metal layer has burned off. That does not usually happen with metal foil units.
Last edited:
Without a motor-run cap or some alternative inductive phase-split, the motor won't start (and will burn trying).
With a motor-start cap in a permanent-split, the start cap burns up later today.
A cheap run cap will burn up next spring (in air-conditioner work).
Mackay Australia is a not-so-small town on the Coral Sea, hot and probably fishy? Unlike my smaller cooler town, it has plenty of cooling technicians and supplies shop. They can supply a known-good 5uFd line-voltage run cap.
With a motor-start cap in a permanent-split, the start cap burns up later today.
A cheap run cap will burn up next spring (in air-conditioner work).
Mackay Australia is a not-so-small town on the Coral Sea, hot and probably fishy? Unlike my smaller cooler town, it has plenty of cooling technicians and supplies shop. They can supply a known-good 5uFd line-voltage run cap.
Attachments
Hey ya!! got this one today, it should work? I'm getting mixed reports :/
5uf
400v B
450v C
My gosh it's so hard to find anything like that in my town
https://ibb.co/ByXfvkL
post pics
That "B" and "C" are only test conditions under which the voltage is rated. So just go ahead.
I am experiencing deterioration in the value of the capacitor.
This time I replaced it with a metalized Polyprolene film capacitor. Hoping it to last longer.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.