Assistance with a faulty Brook Motors manual starter switch for Phase 1 5Hp motor for grain milling machine

[Rossy]

Hello,

We have an old Alvan Blanch mill mixer machine used for processing and mixing grain for sheep and cattle feed.
It is run by a single phase D215 Brook Motors motor that is plated as 5.0 horsepower (Hp) with a full load amps of 22.0.

The motor has, for many years, been started with a manual 'start', 'run', 'off' switch also made by Brook Motors.
The starter model is HC1 and is plated as being single phase, 36 amps and 50 hertz (Hz).

There is now a fault with the switch gear.
The process was to move the switch to 'start' and then, when the motor was up to speed (usually, say two or three seconds) move the switch to the 'run' position.
However, the switch no longer stays in the 'run' position.

I understand (but may be wrong) that the switch would stay (be held) in the 'run' position by a magnetic switch.
When the magnetic switch was turned off, the switch would drop and the machine would stop running (be in the 'stop' position).

It appears that there is a fault with the magnetic switch and would like to explore the options of repairing the existing switch or replacing it with a modern alternative.

I have photographs and diagrams of the switch and the motor connections and will try and upload these.

Both switch and motor were working fine about two weeks ago.

Thank you in advance for your assistance.

 

[Rossy]

Additional images attached

 

[ProDave]

The blue capacitor is wrong, it should be non polarised like the silver one. but that won't be why it is not holding on.

the hold on coil is C on the first diagram. Can you locate it and do you have a multimeter to check continuity of the winding?

 

[Rossy]

Thank you.
Is the Coil as highlighted in the one photo attached?
Yes I have a multimeter and should be able to check continuity with the winding.

 

[Geoff1946]

Simple things first.
Make sure the STOP button isn't sticking.
Then, continuity of the coil, (Yes the one you highlight), then the STOP button contacts, and the hold-in contacts which supply that coil.
I'm not sure I agree with the comment about the blue capacitor. It looks OK to me.

 

[ProDave]

I'm not sure I agree with the comment about the blue capacitor. It looks OK to me.

My bad. I saw "Electrolytic" at the top and assumed it was a normal, polarised electrolytic. like 99.99% of them are.

That is the first time I have seen an electrolytic capacitor rated for ac use. Every day is a school day.

 

[arwooldridge]

My bad. I saw "Electrolytic" at the top and assumed it was a normal, polarised electrolytic. like 99.99% of them are.

That is the first time I have seen an electrolytic capacitor rated for ac use. Every day is a school day.

Unpolarised electolytics are just made up from back to back polarised electrolytics in one can, one of them is always reversed biased so no additional current flows over the normal capacitative current. You can use two ordinary polarised electrolytics and back to back them. One acts as a sort of diode and the other acts as a capacitor alternately. So two 1uF's back to back gives you 1uF, but for very small signals say less than 100 or 200mV it would act like 0.5uF as neither get sufficiently reversed biased, and act like normal capacitors in series. Very rarely used nowadays though I think.

 

[Rossy]

Hello,
thank you for your assistance.

I have taken the magnetic coil (solenoid?) off the starter. Attached are some photos of it.
The piece of blue tape is for my record of where which wire came from. There are no markings on the cables and so, perhaps it does not matter which cable goes where?

There is no continuity between the cable ends.

(I'm learning....)
Does this suggest there is a fault with the coil winding and, therefore, a replacement is required?

Thank you

 

[UNG]

What test equipment are you using for the continuity test

 

[Rossy]

Metex M-3800 digital multimeter, on the sound wave symbol setting.

 

[Rossy]

The STOP button appears to be working okay.
It appears to be 'Normally Closed' with continuity until this is broken by the pressing of the stop button.

 

[ProDave]

Try with the meter on one of the OHMS ranges. the range you are trying is for measuring the forward volt drop of a diode and it's not quite the same thing.

 

[roys]

Unpolarised electolytics are just made up from back to back polarised electrolytics in one can, one of them is always reversed biased so no additional current flows over the normal capacitative current. You can use two ordinary polarised electrolytics and back to back them. One acts as a sort of diode and the other acts as a capacitor alternately. So two 1uF's back to back gives you 1uF, but for very small signals say less than 100 or 200mV it would act like 0.5uF as neither get sufficiently reversed biased, and act like normal capacitors in series. Very rarely used nowadays though I think.

New one on me as well

 

[Rossy]

With dial turned to the 2K ohm setting, the measurement is 0.306 (up to 0.310)

 

[ProDave]

So that is 300 ohms, so that ought to be about right.

Is there anything mechanically stopping it holding?

 

[Rossy]

Thank you.

I cannot see anything mechanically stopping it holding, other than the magnet not being pulled-up.
When pulled up, it moves a lever that then keeps the switch in the 'run' position (this is my understanding).

If I physically move the magnet / coil (?) up, it moves the lever okay and if I then hold the magnet / coil in the up / close position, the mechanism continues to hold the switch gear in the 'run' position.

I attach some photos showing the action, if that helps (or I male no sense).

Prior to seeking advice.....
When I tried to switch the motor on with the cabinet door open, the magnet / coil did not move at all.

I have not taken any more parts of but have tried to dust inside the cabinet.
Perhaps I should try and take the front part off to see if there is anything behind that may be causing the failure?
(I always turn power off and isolate etc on the main circuit board).

 

[Geoff1946]

That is the first time I have seen an electrolytic capacitor rated for ac use. Every day is a school day.

New one on me too. I've only seen bipolar electrolytics in low voltage applications, particularly audio gear.

 

[Geoff1946]

There is no indication of a door interlock, (preventing starting with the enclosure open) on the schematic. - doesn't mean one couldn't have been added on old gear, but it should be obvious if there is one.
If the coil is OK then the something is preventing it being energised. The only thing not on my earlier check list is the overload device. Check the continuity of that.

 

[Rossy]

Thank you

I will investigate more in the morning (as it is now cold outside.....)

Thank you for all your help

 

[ProDave]

I would try it again with the cover off, and fingers out to see that happens.

But first, if you can see the overload device protecting the coil, check it with your ohm meter to see if it is closed, that could have tripped or failed.