Upon measuring the airgap I noticed the runout was almost 0.7mm on one rotor. It seems the previous one assembling it got unlucky and some dirt or debris made it between the shims. After removing that and cleaning it will the runout was reduced to under 0.1mm. I removed one shim (0.3mm) per side and the resulting airgap is around 1.3mm now. Day and night difference in braking as comapred to how it was before. 

I tested the other brake before I rewired it at 96V 28 Amps and it showed the same magnetism pattern so I think all is well. It seems one brake I have which has still the tag on it is a CC135. The other one doesnt have a tag anymore and it looms identical but the airgap is noticeable smaller so I think it is a CC160. 

would it be smart to reduce the airgap on the CC135? The braking feels noticable less when spinning the rolls by hand

Ok so changing the wires to this situation gives me 12 Ohm and 16 amps at 192v. 

What might be odd is if I use a screwdriver it gets pulled to the rotor every 2 magnets which is odd as the drawing says there should be N S N S pattern but mine feels more like S S N N 

i tried then to change the wires feeding one corner (2 magnets 4 coils) and then the brake doesnt seem happy. The magnetism somehow pull the rotor so far it rubs the pole shoes 

Other brake has some visible colours. Looks like it has these withe wires parraleling the coils. 

im gonna grasp all my courage and rewire it per the diagram in the previous post 🙂

@force26 when I said rewire, I did not mean rewire the coils themselves (unless they are damaged of course). Just how the coils are connected to each other. They should all be in series. 

When you review them, take care because the wires are quite brittle since they are aluminium wires. 

For 16 Amps 14 awg is plenty. 2.5mm in europe =)

Hi Jostein,

As i read rewiring coils should be done with copper wire, any ballpark figures on gauge?

Hi,

A stage is one coil. You have 16 coils so you should see 16 x 0.75 = 12 Ohm. This will give around 16 Amps at 192V. 

If the retarder is wired for 96V you will see something like 4 Ohm. I recommend rewiring to 192V, as this will significantly lower the current. With 96V the current is double for half the time and nothing on the other half, so the mains are loaded very spikily. 

Rewiring means all coils are in series. Just ensure the coils receive the same polarity as before and it will be fine. 

Do you know what the resistance should be when I measure the coils at the wire going to the controller? Ive bought 2 CC135 of a guy using them as dyno before and he said he just used 220v mains with a rectifier and chopper to control it. When I measure the terminals where the wires to the power supply go I measure around 3.4 on one and 4 Ohm on the other brake. there are 2 wires joined at each post but cant distinguish any colors. when i read the Telma manual they are stating 0.75 Ohm per Stage, but I dont really know what a stage means. If it would be wired to be 30 Amps at 192v I would expect something like 6.5 Ohm 🍕

Yes, i made the adapter shafts myself. With a small manual lathe it was bit PITA to make them 🙂

Im sure any machine shop can make these adapters pretty easily.

Good point, i have a megger to use... so you made adapters also by yourself? There is small machine shop makin transmissions etc for rally quite near where  i live, im gonna gather my parts and ask if they can make shafts.

Timo

I made coils with lathe witch had lap counter and stand for coil wire.

Make sure you do a resistance and insulation resistance measurement with 1000 volts. Thats only way to find out does the old coils really work...

-Arttu

It was PITA to remove poleshoes, so coils are about the same. I measure coils next week and if they are good i only rewire.

Did you make some sort of coilwinder for rewind?

Timo

Posted by: Force26

Hi,

I bought couple of Telmas from junkyard... I would like to disassemble them for cleaning and rewiring. How can i uninstall coils? They seem be stuck on centerpiece. 

Cheers,

Timo

Hi

The only way i got the coils removed was to destroy them. I had to rewind all coils in my CC200...

-Arttu