Table saw motor wiring

[polaroid]

Hello people. My old man has a table saw and water has got in the switch, he decided to remove it ready for me to replace and due to poor memory can't remember how it was wired up.

I've not had much experience with motors etc but from what I can work out it's wired as follows:

I haven't checked the windings but these are the connections - the nice bright white cables are the capacitor:

I've got a new NVR switch so I assume it's N = 0v and BR & BL = 230v?

From what I see online it's an unusual setup as most single phase motors only have two windings with a capacitor shifting the phase for the second winding.

Cheers!

 

[marconi]

I have submitted a query to FERM Genemuiden NV on how the wires should be connected.


FERM DIY - Power Tools - Power to create - https://ferm-diy.com/en/power-tools

 

[marconi]

Ferm replied but had no information amongst their records on the motor for this old table saw.

please draw out switch wiring and post some pictures too.

 

[polaroid]

Ferm replied but had no information amongst their records on the motor for this old table saw.

please draw out switch wiring and post some pictures too.

Thanks for your time Marconi.

Unfortunately I don't have the wiring of the old switch, this is the issue.

I have few pics of the old NVR switch mech which i forgot to post the other night. Just no clue how it was wired up.

I appreciate this is an old saw so it's not worth a lot however I'm learning a great deal from this and it has me very curious as it appears to be a very unusual setup.

 

[polaroid]

I have read some single phase motors have start/run windings with different resistances so that may account for the values i got. However, all the single phase motors i find reference to have two windings.

 

[marconi]

I need to find a reference to confirm but I reckon after studying your winding diagram, your mention of a nvr switch and the fact this is a table saw and therefore short duty operation Ie short periods In use and much longer off

1. The motor will be a permanent capacitor split phase induction motor perfect to give high starting torque for rapid acceleration up to high speed 3000rpm and good speed regulation;

2. One would want the supply to be only held on when the supply is available and at the correct voltage and frequency.

3. If the motor stalls or the speed drops below a certain rate the supply is disconnected;

4. If the motor fails to start to turn or does not run up and exceed a certain rate the motor supply cannot be held on.

5. The motor must turn at sufficient speed for the fan to cool it.

Requirements 2 to 5 can be met if the motor speed is sensed. I think but need to check that the lowest resistance winding is a coil which senses electromagnetically the rotational speed of the motor. the output of this coil is the energising supply for the hold on coil in the no volt release switch.

see attachment for how the wires should be connected at the motor. Blue and brown are 230V supply to start and run,windings. Between Black and blue is the generated voltage indicating satisfactory speed of rotation which is connected across nvr contactor coil.

I will research typical nvr switches as used in saw tables but that will be tomorrow morning now to confirm my line of thinking.

 

[brianmoooore]

I have read some single phase motors have start/run windings with different resistances so that may account for the values i got. However, all the single phase motors i find reference to have two windings.

I've thought earlier that the wiring diagram of that motor makes much more sense if the winding on the yellow wires is deleted, and the resistance ratio between the other two is approximately what I would expect.
Marconi could well be onto a winner with his idea of a feedback winding to control the NV switch. Makes sense, and uses up a couple more of the surfeit of terminals on that switch.

 

[Lucien Nunes]

I've only just skimmed the thread for the first time but surely the two yellow leads with 0.14Ω between them would be a thermal overload cutout in series with the neutral end of the hold coil of the NVR switch?

 

[marconi]

There are 4 terminal and 5 terminal NVR switches for single phase motor applications such as your FERM table saw. In both the 4 and 5 terminal switch the hold on coil is 230V ac mains voltage.

There is no way that the motor has a 230V ac sense coil with only a resistance of 0.14 Ohms - the wire would have to be too thick and thus the winding too bulky to fit inside the motor. The device between the yellow wires with a resistance of 0.14 is - as Lucien keenly and helpfully observes a switch - a thermal cut out switch. I feel a Captain Mainwaring moment - 'I was wondering when someone would spot that'. My musings 3-5 were fanciful - only 1 and 2 apply.

The form, fit, function for the switch in the image you posted is met by a KJD18 with 5 terminals but do check dimensions:

ChaRLes 250V 15A Kjd18 Switch 5 Pin No-Voltage Release Switch Plastic : Amazon.co.uk: DIY & Tools - https://www.amazon.co.uk/ChaRLes-Switch-No-Voltage-Release-Plastic/dp/B07VDR3J3G/ref=sr_1_8?dchild=1&keywords=kjd18&qid=1626145243&sr=8-8#descriptionAndDetails

See attachment - ignore unused contacts 5 and 6 of image - I could only find a picture for a KJD18 7 pin for 3 phase 400V ac.

 

[polaroid]

Awesome thank you all, Lucien for the penny drop moment and a special thanks to Marconi for your time!

I'll report back when it's sorted.

 

[marconi]

You may need to buy some spade terminals and crimper to make the connections to the switch.

Amazon.co.uk : Spade Terminals - https://www.amazon.co.uk/Spade-Terminals/b?ie=UTF8&node=10256656031

 

[polaroid]

You may need to buy some spade terminals and crimper to make the connections to the switch.

Amazon.co.uk : Spade Terminals - https://www.amazon.co.uk/Spade-Terminals/b?ie=UTF8&node=10256656031

Yeah, I'm putting a new enclosure on it too with some decent glands due to the previous water ingress. Should be good for a few more years after!