dobbslc
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You might be right there,
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dobbslc
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Well I've tried just about everything suggested but still no joy.
I've borrowed a capacitor tester and got the following results,
The 25uf run cap measures 25uf.
The 200uf start cap measures 380uf. There is a resistor on this that I removed before testing hmmmm. Although I swapped them round with no difference.
Meggered the coils at 1000 volts to earth and they are both clear.
Measured 0.65 ohms on one coil and 1.35 ohms on the other ( can't remember which was which now)
The stop start switch is fine.
After swapping caps around with no difference I got a bit medieval on it and bridged the 13amp fuse with some wire it now starts and runs for a couple of seconds before poping the 15 amp overload trip on the side.
It makes a loud buzzing sound when it runs and doesn't seem to be up to speed (2800)rpm.
I noticed the centrifugal switch seems quite stiff to push in, much more than the old motors I used to fix at a bowling alley. It needs two fingers to push in, the old ones you could almost flick on and off with light pressure.
Would this not switching the start coils off cause this fault? ie running both coils at once for too long.
I've borrowed a capacitor tester and got the following results,
The 25uf run cap measures 25uf.
The 200uf start cap measures 380uf. There is a resistor on this that I removed before testing hmmmm. Although I swapped them round with no difference.
Meggered the coils at 1000 volts to earth and they are both clear.
Measured 0.65 ohms on one coil and 1.35 ohms on the other ( can't remember which was which now)
The stop start switch is fine.
After swapping caps around with no difference I got a bit medieval on it and bridged the 13amp fuse with some wire it now starts and runs for a couple of seconds before poping the 15 amp overload trip on the side.
It makes a loud buzzing sound when it runs and doesn't seem to be up to speed (2800)rpm.
I noticed the centrifugal switch seems quite stiff to push in, much more than the old motors I used to fix at a bowling alley. It needs two fingers to push in, the old ones you could almost flick on and off with light pressure.
Would this not switching the start coils off cause this fault? ie running both coils at once for too long.
Would this not switching the start coils off cause this fault? ie running both coils at once for too long.
I think it might, though I'd have expected more than a couple of seconds before it went out - could you disconnect the start cap once it's running? Or just disconnect the start cap anyway and then give it a spin to start it?
carbon
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Ive had that before, the motor would run for a few seconds then blow the fuse. The centrifugal switch wasn't working. Dismantled the motor, lubricated it and made sure it could move. Motor ran fine afterwards. The 200uf cap I believe has a lower working voltage than the 50uf run cap but if the value is higher than stated on the case it doesn't cause a problem it's when the value is a lot lower that it becomes an issue. Free it off and try it, you may have a cheap working compressor after all
dobbslc
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Well I've put in a new 200uf starting capacitor and it made little difference, the motor will spin for a bit longer be for it trips out.
It still makes a right noise as well, I checked the centrifugal switch and fiddled with the springs a bit then tested it was working by the string pull method, it seems to switch ok.
I don't think the switch was seized or anything it's just quite stiffly sprung.
Don't know what else to try really unlesss its the run cap but that tests out ok.
Help!
It still makes a right noise as well, I checked the centrifugal switch and fiddled with the springs a bit then tested it was working by the string pull method, it seems to switch ok.
I don't think the switch was seized or anything it's just quite stiffly sprung.
Don't know what else to try really unlesss its the run cap but that tests out ok.
Help!
Can you add a switch in series with the starting cap and turn it off the moment the motor starts? (Or just pull a lead off if that's possible?)
(Actually, you can probably disconnect both caps once the motor's started - if it still trips, then it's nothing to do with caps, switches or the aux winding.)
(Actually, you can probably disconnect both caps once the motor's started - if it still trips, then it's nothing to do with caps, switches or the aux winding.)
Bladevane
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Did you check the condition of the contacts on the switch? I ask because my pillar drill motor has just failed. It too made a horrendous noise and smoked during running. The 2 coils were the same resistance but the switch contacts were pretty burnt out. My diagnosis was that it was not switching the starting coil in and out cleanly. Not sure what else to suggest.
carbon
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I didn't notice this earlier but is the run cap 50uf or 25uf
If its a 50uf one and it measures 25uf then the motor could draw more current to run, causing the fuse to blow.
If its a 50uf one and it measures 25uf then the motor could draw more current to run, causing the fuse to blow.
dobbslc
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Yeah it's 50uf I don't know where I got 25 from.
I've tried swapping caps / without caps it doesn't make any difference.
The switch contacts were a little burnt but seem ok now I've cleaned them up and as I said it seems to be working ie switching off when I spin the motor with string.
Bit of a pig this one!
I might just try plugging it in in the house to see if volt drop is a factor down the garage, but I think that's clutching at straws.
dobbslc
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Well I've disconnected the centrifugal switch and replaced it with a 13a spur so I can manually turn off the start coil, it will now spin up to what seems like full speed for a couple of seconds before tripping again. I can hear the switch disingaging once it's up to speed so I think it's ok, the motor case gets hot very quickly so I'm sure the fault lays within the run circuit.
I've ordered a new 50uf run capacitor so will see what happens with that fitted.
I'll keep the post updated when I find something new.
Thanks for the help so far.
I've ordered a new 50uf run capacitor so will see what happens with that fitted.
I'll keep the post updated when I find something new.
Thanks for the help so far.
Screwdriver
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It's been a week already and you still haven't figured out you need a new motor!
Seriously dude. Get a new motor, get on with life.
Seriously dude. Get a new motor, get on with life.
dobbslc
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My fault, I meant the start capacitor. I just wanted to isolate the switch from the equation.
I like to be sure what's wrong before spunking cash on a new motor especial as the windings both meter out as ok.
I own a Vauxhall diesel engined car and if I had the "just buy a new one attitude" when it goes wrong I'd have 15 of the poxy things outside my house!
dobbslc
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That's what I keep saying!
It's being sold now. I've finally said I've had enough of it.
I will never buy anything Vauxhall again, terrible ****e vehicles.
normspanners
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all the centrifugal switch is doing is switching out the start CAP which leaves just the run cap in circuit when above certain RPM, the start winding runs in conjunction with the run cap to give the motor more torque and if disconnected it will O/L the motor
here is a simple diagram
FIGURE 1.16 Two-value capacitor, single-phase motor.
Improved full-load power factor: 10-20 points Reduced full-load running current Reduced magnetic noise Cooler running
The addition of a running capacitor to a single-phase motor with properly designed windings permits the running performance to approach the performance of a three-phase motor. The typical performance of integral-horsepower, two-value capacitor motors is shown in Table 1.7. Comparison of this performance with the performance shown in Table 1.6 for capacitor-start motors shows the improvement in both efficiency and the power factor.
The optimum performance that can be achieved in a two-value capacitor, single-phase motor is a function of the economic factors as well as the technical considerations in the design of the motor. To illustrate this, Table 1.8 shows the performance of a single-phase motor with the design optimized for various values of running capacitance. The base for the performance comparison is a capacitor-start, induction-run motor with no running capacitor. Table 1.9 shows that performance improves with increasing values
The text I have coloured red ring any bells ??
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