Motor starter help.

[marconi]

The guru on old electrical equipment is Lucien not me. I just like the odd electrical problem to mull over to keep the grey cells firing. I've probably stood on his toes on this one - sorry to him.

EF folk may be interested these links on Newman electric motors:

http://vintagemachinery.org/mfgindex/detail.aspx?id=9415

https://www.gracesguide.co.uk/Newman_Industries

https://www.yateandsodburyvoice.co.uk/the-history-of-newman-industries-of-yate

 

[Scott_fd2r]

hello again.

today I was back at the motor,
the voltage is only around 220v at the starter. during starting this can drop to around 212v, during running its is around 218v.

everything has been ok since i was last there, but i am told the mill/bruiser throughput is less than with the previous motor. i did some load tests. the motor draws around 36A at startup and quickly settles to around 11A. as the grain flow is increased the load rises to around 15A. at this flow the operator says it will run constantly with no problem. if the flow is increased further the load can rise to around 20A but at this rate the current is very unsettled jumping from 18-22A the voltage remains steady at 218v. if the flow is increased by just a fraction more the load jumps to 30+ amps and the motor stalls and sits humming until it is stopped or trips.
the rpm never alters much from 1400 just drops immediately as the current shoots up and the motor stalls

i checked the current on both windings at each stage and the windings appear well balanced with the currents exactly the same at each stage. (half of the total load drawn).

they are happy to leave it like this for now and run with a reduced flow rate until the other motor is rewound and refitted. just posted this info incase anyone was interested

 

[Pete999]

Hi all, thanks again for any input.
I have been asked to look at this starter as motor starts ok, but when switches over to run motor stops and starter just hums.
First of all like I’ve said in previous posts I haven’t had a lot of experience with motors/ starters etc
Am I right in thinking this starter is for a capacitor start - capacitor run motor with no centrifugal switch as it has a timer set to 15 seconds and then 3 contactors?
The motor starts ok and contractor in middle kicks in and contractor on right kicks in but after time delay right contractor drops out, but left one doesn’t kick in.
The part I’m not sure about is that there is a 1M ohm resistor across the 13 and 14 contacts on the left contractor and if I bypass this with some cable it all appears to work fine. I have checked resistor and it reads 1M ohm like it should ( brown, black, green and gold).
Could anybody tell me why the resistor is there in the first place and what it does ( is it to stop a back feed?) and why the starter seems to work fine when I bypass it yet it is reading ok???
Thank you
[automerge]1575303628[/automerge]
Also forgot to mention there is a cable from 14 terminal to A2 of run contractor..

Is this a SP OR TP Motor?

 

[Lucien Nunes]

Its single-phase, but it turned out to be a 480V motor that had been installed second-hand as a replacememt by mistake on a 230V supply and also incorrectly wired internally at the time the OP first encountered it. The behaviour is consistent with the voltage mismatch, as at 1400 rpm it's running below rated full load speed even at moderate load. Unfortunately an earler measurement of the speed in post #41 indicated it was reaching 1490 rpm off load which suggested the voltage was correct.

Thanks for the update @Scott_fd2r, it's good to hear the original motor is being rewound.

E2A Pete that first post was actually about a different motor from last year

 

[marconi]

Re:
today I was back at the motor. the voltage is only around 220v at the starter. during starting this can drop to around 212v, during running its is around 218v.

The off-load supply voltage at the starter is somewhat low at 220V. Is this the voltage at the input terminals of the main switch for the building? Does the building have a high current demand from permanently energised loads which is causing a significant voltage drop? What voltage does the incoming supply rise to when the building's main switch is opened?

As a simple rule of thumb the power of a motor is proportional to Vsquared so a motor wound for 240V would produce about (220/240)squared = 80% of its rated power output. Is the motor powering the machine often required to operate at rated power? Could this be a factor in why the previous motor burnt out? Some thought then into what voltage to rewind the motor to operate at.

And an investigation as to whether the incoming supply is 'weak' because of some external high resistance connection. What for example are the line-neutral voltages in neighbouring buildings using the same DNO distribution cables - could you measure these?

 

[Farmspark]

Evening, I have a similar issue with a grain mill where farmer has given me a 5hp motor and this starter box. Connections to A1,A2,A3 and A4 seemed straight forward but the 2 capacitors in series that go through the first stage contactor on left (red and white wire in con block) I am unsure of terminals to attach to on motor. Any help please? They come out of connection on second stage after a 4 second timer.
Stage 1 main contactor (with O/L) and left contactor go in, controlled by timer on left. Stage 2 middle contactor and main contactor go in.
thanks in advance

 

[marconi]

Evening, I have a similar issue with a grain mill where farmer has given me a 5hp motor and this starter box. Connections to A1,A2,A3 and A4 seemed straight forward but the 2 capacitors in series that go through the first stage contactor on left (red and white wire in con block) I am unsure of terminals to attach to on motor. Any help please? They come out of connection on second stage after a 4 second timer.
Stage 1 main contactor (with O/L) and left contactor go in, controlled by timer on left. Stage 2 middle contactor and main contactor go in.
thanks in advance

Do you still want help with this or have you fathomed it out already?