Thread: Motor Issue

Originally Posted by PDW

Well, seeing as the whole point of the start cap is to provide an artificial phase shift to get the magnetic field to get the rotor to rotate......

Well there was the idea that maybe with no load on the motor the run cap could provide enough rotation to get it going. I cant even remember off the top of my head what the run cap is for I always have to look it up. I'm pretty sure its in the wrong place lol. I should also have remembered from the first motor the start cap died on that they just sit and hum. I know I could bump start it but that doesnt have much appeal ......maybe wiring it up so it can run in either direction would be handy(though I cant see why for a grinder).

Originally Posted by PDW

You still have wired fuses? Would you like me to send you a handful of DIN mount mini circuit breakers? I have a number of spare single phase 15A ones as I've pretty well replaced all of mine with 15A RCD breakers.

Yes fuses on the sub panel in the shed, the house panel has circuit breakers and RCD. Thank you but I have several sub panels from some gear I scrapped, but the world would end if I was to replace the panel myself so they sit on the shelf waiting to be used on a machine maybe. This is the second fuse I've blown in 23 years so its not been much of an issue or I guess I would have got off my ass and had it done. As the work the sparky does has to be inspected by someone else to get a "certificate of electrical safety" I don't see why I cant do it. I guess I should be happy I'm still able to walk on the footpath without a helmet, let alone have the machine I do in my shed.


Stuart

hi stu the lathe wasn't down long hay.
who says you cant do it stu? Its
your house.

Originally Posted by Stustoys

maybe wiring it up so it can run in either direction would be handy(though I cant see why for a grinder).

I can see advantages for a grinder, extra fast wheel removal comes to mind.... switch on and step back....

Regards
Ray

Hi Stuart,

Good to see you have fixed your motor problem. I must confess that my lathe has a similar issue. It will start OK at low gearbox speeds but once a spindle speed of 600 rpm or higher is selected, a helping hand on the chuck is needed. My lathe top speed of 1400 rpm is not operational ATM because it requires too much torque from the motor (even with some help) I have not blown any fuses or RCD's (yet). For higher speeds, I find running it at slower speeds first to warm up the oil and reducing viscosity helps!

I'm assuming it's a start cap too but can't be sure. I have a 3 phase 3 HP (re-wired in delta) motor ready for a VFD conversion but have not got around to it yet. Since my shed is not yet hard wired to the house, I run couple of extension leads for power. I suspect that the voltage drop on start up may be a contributing factor but not sure.

Shed will be wired in next year. Yay!!!!

Simon

if your local supplier is closed you may get one from any of the refrigeration wholesalers ie heatcraft, actrol, airefrig or even reece or boc

Originally Posted by simonl

Hi Stuart,

Good to see you have fixed your motor problem. I must confess that my lathe has a similar issue. It will start OK at low gearbox speeds but once a spindle speed of 600 rpm or higher is selected, a helping hand on the chuck is needed. My lathe top speed of 1400 rpm is not operational ATM because it requires too much torque from the motor (even with some help) I have not blown any fuses or RCD's (yet). For higher speeds, I find running it at slower speeds first to warm up the oil and reducing viscosity helps!

I'm assuming it's a start cap too but can't be sure. I have a 3 phase 3 HP (re-wired in delta) motor ready for a VFD conversion but have not got around to it yet. Since my shed is not yet hard wired to the house, I run couple of extension leads for power. I suspect that the voltage drop on start up may be a contributing factor but not sure.

Shed will be wired in next year. Yay!!!!

Simon

hi simon have you tried running a thicker cable from your house to shed.
aaron

Originally Posted by Stustoys

Thank you but I have several sub panels from some gear I scrapped, but the world would end if I was to replace the panel myself so they sit on the shelf waiting to be used on a machine maybe. This is the second fuse I've blown in 23 years so its not been much of an issue or I guess I would have got off my ass and had it done. As the work the sparky does has to be inspected by someone else to get a "certificate of electrical safety" I don't see why I cant do it. I guess I should be happy I'm still able to walk on the footpath without a helmet, let alone have the machine I do in my shed.

Don't give them ideas....

Funnily, I am about to run another 32A 3 phase line to my repaired air compressor from a sub-board...... I work on the principle of oversizing the cable WRT the breakers and making sure the wire is mechanically protected from any physical damage. IOW know the current draw and don't cut corners. The only comment I've ever had from an inspector in the past was, the wiring was obviously not done by a licensed electrician as it was too neat and well done. I can live with that.

PDW

Originally Posted by A J in WA

Try this. Disconnect the motor from the mains - yes - obviously - disconnect at least one capacitor from the motor. Apply 12 volts from a car battery to the capacitor for about 5 to 10 seconds. Short the capacitor leads together immediately. You should get a spark, and maybe a "crack." No discharge probably means the capacitor is dead. Alan.

This represents a reasonable and practical test method but is not truly definative. I.e. a cap that passes this test may still not work insitu due to the voltages involved. With 240V AC around the motor the cap voltages can be 10-20 times higher than the 12V test voltage, and cause dielectric (insulation between capacitor plates) breakdown and starting issues. When the motor starts to have issues with reluctant starting, the problem is normally due to dielectric breakdown inside the cap at the extreme peaks of the sine voltage waveform, but the issue then tends to extend to occur at lower voltages making the problem more severe.

However, if a cap fails the 12V test outlined, it is definitely cactus and due for replacement.

Originally Posted by azzrock

who says you cant do it stu?

Thats a pretty long list!

Originally Posted by RayG

I can see advantages for a grinder, extra fast wheel removal comes to mind.... switch on and step back

hmm I hadnt thought of that...... though I think its the wrong way now(though its only a small diamond wheel)

Originally Posted by PDW

Don't give them ideas....

Yeah I hear you.
Great that you can do your own work and get it inspected, not an option here, in fact last I heard from a sparky mate even they have to pay about $1500 a year to have the paper work to let them do it now. As his day job is industrial he doesnt bother paying so can't even work on his own house and get it inspected.
We currently have a goverment program paying A grade sparkies to change down lights to LEDs...... no wonder I cant get one.


Stuart

p.s. Simon, thats how the cap on my first motor went. Thats why I wasnt sure it was the same thing this time.

In Vic if a sparky wants to charge money for electrical wiring ect he has to have a contractors
license. how ever if a A grade sparky does not charge for the work ie a love job. They
only needs the license but must put in the certification of electrical safety.
Its over the top In your own house if you know how or are suitably trained why
shouldn't you do it. were not even ment to change a light fitting.

Originally Posted by azzrock

In Vic if a sparky wants to charge money for electrical wiring ect he has to have a contractors
license. how ever if a A grade sparky does not charge for the work ie a love job. They
only needs the license but must put in the certification of electrical safety.
Its over the top In your own house if you know how or are suitably trained why
shouldn't you do it. were not even ment to change a light fitting.

same for SA

also applies to most building trades...eg tilers, carpenters builders etc etc

if unlicenced and they do a crappy job they cant take you to court if you dont pay...

hi eskimo. how are you. The differance here is Its not just about them being liable
Like builders and tilers. its the fact that its illegal to do unlicensed elecrtrical
work. Which i think is great in the work place. not so great at home.
at least stu got his lathe going.
stu is it your mill that you run of a vfd.
aaron

Yea, the double extension lead trick is not something I'm proud of. It will be fixed in the new year thank god! The wife, while certainly has no problems with me having power (she knows it's a necessity) in the shed, she does realise once I have power and lighting, I will be spending more time there day AND night!

PDW, I have done some small electrical work in the past and it's always a darn sight neater than any sparky I have ever seen! My house is 6 years old… You should come have a look in my roof! Most of you would be horrified. Apparently it's all certified, even the 3/4" poly gas main for the central heater that runs over the top of a halogen downlight

Simon

Originally Posted by simonl

Yea, the double extension lead trick is not something I'm proud of. It will be fixed in the new year thank god! The wife, while certainly has no problems with me having power (she knows it's a necessity) in the shed, she does realise once I have power and lighting, I will be spending more time there day AND night!
Simon

Hi Simon. hope your well. Do you mean that you ran two conductors in parallel?
dont worry i even think that's legal. As long as both conductors are the same size
and bigger than 1mm.
aaron