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Evening guys. I had replied last night but cant see my post anywhere. Dont know whither it went on or not.
Just for info this starter and motor were used together it started and ran without issue. Since then they were disconnected and not marked so i thought the problem to be a wiring mixup but i cant see how else is could be connected using 5 wires. It was definitely connected to a single phase line neutral 230v supply before. It could be that the load was less so this issue didn't show up? The motor and starter are now on a different mill, but it looks very similar in size with pulleys the same size.

today i started the motor by spinning the mill slightly first then starting it. When it is up and running it is doing 1490rpm with the mill running. So pretty much spot on what it should be.
I removed the belts and started the motor to prove the centrifugal switch. I tested between bottom right terminal and A3. Which is closed circuit at startup then open circuit when it reaches speed. I can actually hear the switch open.
This could be useless info but the cables disappearing into the motor are in sleeves cables z2+sw go in the same sleeve an head towards the fan end of the motor. A2+A4+z1 go in a sleeve towards the front of the motor. The rest appear to go in another sleeve.
i did the resistance tests with the supply cables disconnect but have left the paper in my jacket pocket. I will post these readings later.
hope that makes some sort of sense.
 
Well it sounds like you are in luck with the voltage, as I can't believe it would slip only 10rpm at half voltage even off load. But it's daft for the plate not to give 240 / 480V options with the two different currents as is normal on a reconfigurable motor. Obviously series/parallel starting is available at 240V but at the nameplate 480V it would have to be DOL as the windings would already be hard-wired in series for running.

So just fix the start winding connections so that the cap and winding are in series, optionally bypass the switch if you trust the starter, and personally I think the start circuit should be across full 230V mains, not connected to the main winding midpoint. Marconi (& anybody else out there) what say you?
 
Scott_fd2r: I have now studied the blueprint for the Brook Crompton Series Parallel starter and arrived at the following advice:

(see attached diagram here and the B_C blueprint in my last message).

1. The motor is CSIR with an integral centrifugal switch - this switch is to be used as it is the reliable way to de-energise the start winding Z at the appropriate speed - so we DO NOT use the starter to switch in/out the Z winding. The connection from the motor Z terminal to the starter is INCORRECT and should be removed.

2. The motor is wired for series-start and parallel run. I will come on to the 480V question at the end. Wire the motor terminals as in the attachment below.

3. The motor is connected to the starter by 4 conductors viz A1, A2, A3 and A4. These connect to starter as A1 to U1, A2 to U2, A3 to U5 and A4 to U6. Top right wiring diagram on blueprint refers CSIR Series 1.

4. Now study the note numbered 6 on the blueprint - read it very carefully and make the connections as in para 3 above, and CONNECT a link between 62 and 54 on Run(RN) contactor - or check that one is there already - this link is required because the motor is using its centrifugal switch.

5. Now study wiring schematic of blueprint above the notes and make sure that at the overload the wiring is done in accordance with the note - 'or cap start/Ind run disconnecvt from 2 and connected to 4.

6. Make sure incoming L and N go to 1 and 5 on contactor C.

7. Check/adjust timer delay so that changeover from series to paralle occurs BEFORE centrifugal switch opens.

8. Energised by a 240V 2 wire supply the motor in the run state will produce less mechanical power than on a 480V 2 wire supply. I'd estimate 25 per cent less so about 2.5kW output. Power being proportional to Vsquared or Isquared. You can calculate it roughly by the product of supply voltage and motor current times a nominal power factor of say 0.8.

9. Caution - the capacitors may need replacing.
 

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Marconi.
Today i rearranged the cables almost identical to your drawing. However i ended up using the starter to switch the neutral as cables i have coming from the motor didn't allow for exactly what you have drawn.
the cable Z goes from the capacitor and straight into the motor. I have attached a picture or how i have it connected now and it seems to be working as it should start up torque is far better. Timer is set at about 3 or 4 seconds which gives a smooth changeover. Is there any reason why i shouldnt be using the starter to switch out the neutral?

On start up its drawing about 38 amps and settles to around 15 when running on load.

if the rollers are squeezed together too quickly After it reaches full speed the contactors drop out. It doesnt trip the overload they just stop. I never actually checked the voltage to see if it is causing a voltage drop to de energies the coil i doubt that is the case though. Its not an issue as the rollers can be squeezed together slowly giving the idle roller time to get upto speed. I just wondered if there was an obvious reason for this?
 
Scott - good evening. I'll think on your last post tonight and reply tomorrow - I get up early.

Could you describe/draw how the motor is actually now connected to the B-C starter by reference to the motor terminals (my As1-4 and Zs1-2) and the starter terminals (Us1-4 and Z)? If wiring has been done as I advised then A4 is a permanent N so Z2 can be connected to it - and thus no need for a fifth wire from Z2 back to the starter to connect to N.

I would appreciate it if you could take some voltage measurements at the input to the starter as I mentioned for the stop, start and run phases.
 
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Good morning. As numbered points:

1. We don't need to use the starter to switch out the N for the Z coil because its N can be obtained from A4 and the centrifugal switch will de-energise the coil when the motor is close-enough to normal running speed for induction only motoring. Being a centrifugal switch it will actually operate at a speed - using the starter would switch based on a time delay.

2. Starting current of 38A and running current of 15A; you can see why series parallel is used to start the motor. The initial starting current would be much higher if both A windings were in parallel abd connected DOL - quite a 'shock' to the sub-main to the motor starter and the supply in general.

3. 15A running - 230 x 15 x 0.8 = 2.8kW electrical power so about 2.5kW mechanical power.

4. That the contactors drop out indicates to me the supply voltage at the starter input terminals is sagging far too much when the motor running current is higher than the normal operating current. This will happen anyway as the motor slows down under load and be made worse still if the centrifugal switch switch closes again. I wondered in one of my earlier posts if the mains supply and the sub-main to the motor starter were 'weak'. Those voltage/current measurements during stop, start and run and then under normal grinding load will provide information on the voltage drop. Could you also estimate the length of the sub-main run and determine its conductor size? We can then do a volt-drop calculation.

5. Could you tell me and perhaps post some photos of the mill machine and tell us what it used for and how it is operated ie: short burst milling or prolonged milling of a batch of grain. I want to consider the adequacy of this motor (I still believe it to be a 480V two wire circa 10HP being operated at 240V now so 2.5kW output. It may well be under-powered for the work to be done unless there is some other problem with the mechanical drive chain, gearbox(?) and mill wheels/rollers necessitating the motor to work harder than it should do.

6. I reckon - in other words what I would do if I was you - that the machine and its wiring and starter needs a thorough checking over including connections, safety interlocks, trip settings, earthing and bonding, bearings, roundness of rollers and wheels - to ensure it is fit and safe for purpose. I recommend you let the client know and secure his approval and funding for these checks.

7. Only 'cos I am curious and it adds to the interest could you tell me where you are in Ayrshire?

8. REMEMBER and USE ALL YOUR TRAINING ABOUT WORKING SAFELY ON ELECTRICAL AND MECHANICAL EQUIPMENT.
 
Today I asked B-C technical department about the release voltage of the contactors used in the starter.

As a rule of thumb the release voltage is between 50-70% of rated operating voltage. Release or drop out is when the contactor coil's holding force no longer exceed the spring pressure designed to open the contacts quickly.

During contactor closure, the reluctance decreases rapidly which aids the rapid rise in the force of closure. But during voltage dips the force of separation may rapidly exceed the force of holding - which opens the magnetic circuit a little - which causes an increase in reluctance which causes a further decrease in holding force - so the spring pressure becomes more dominant.........so the opening widens further.....so the reluctance increases .......

Imagine bringing to bar magnets together N to S and then separating them.
 
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hello again. yes that all makes sense.

i have added the the contactor connections to my drawing of how the motor is connected just now.
I'm back at work today (at my real job) for 5 days so I wont be back at the motor until next week. i will get some accurate voltage readings at stop, start and run then.

i have no real evidence yet, but i would doubt if the voltage is dropping as much as 30-50% as i would have expected the lights to dim or flicker if that was the case. i have seen that happen in the past when big single phase motors start. i will know better next week after some voltage tests.

i am from a village called Ballantrae in South Ayrshire.

i want to thank Marconi and lucien nunes for all you help and advice. the whole thing could have been flung in the skip by now if it wasn't for you input
 

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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
 
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?
 
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
 
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?
 
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
 

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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?
 

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