Q&A Forum
Att: Jostein
What setup would you recomend for this eddy current brake:
Telma AE30-32. 350NM
24V 24A or it can also be rewired to 72V 8A.
I do only have the brake at the moment !
Kind regards Henrik
Hi Henrik,
Good question!
You have a few options. In the end what you want is a 0-72V or 0-24V DC power supply controlled by a PWM or analog input, which is able to provide enough current.
First I would check is if there is an off-the-shelf power supply that could do the trick. I took a quick look and this one is almost there:
https://www.alibaba.com/product-detail/SCN-600-24-CE-approved-0_60069207637.html
It costs nothing and can deliver more power than you need. Voltage is adjusted via a 1V-5V analog input, but unfortunately only from 20% to 100%... Does it work with 0V-5V and 0% to 100%... worth contacting the company to see. Or just continue browsing, AliBaba and eBay have a lot of stuff!
Another option is to use the Semikron solution, with a step down transformer in front (230V to 80V for example). Note though that designs based on chopper modules like the Semikron are a bit more tricky to get right when you introduce transformers, you typically need more protection filters against over voltage (these filters are called snubbers). I would not go this route if there is a good off-the-shelf solution available.
Maybe someone else has good ideas?
Cheers,
Jostein
Hi Jostein
I have been looking hi and low at ebay and alibaba without finding anything that can do the job. Always adjustable from 10/20% to 100/120% .....newer from 0% to 80/100%....
So I have been thinking in another direction ! As a former forklift mechanic i got to think about chargers for 72-80V forklifts. It is a simpel big transformer and rectifier bridge. Could this be used for power supply either in a 24V or 72V setup ?
Regards Henrik
Hi,
The idea of the forklift charger is not going to work, because it gives out a fixed voltage. But the transformer from this setup may be used to create a lower voltage and feed that into the solution from NuWaveTech.
Or you can go for a 1:2 transformer so you create 115V (from 230V). Then feed this 115V signal into a Semikron SKPC200-110 and an SKCH28, that should work. You need to control the voltage such that it does not exceed 72V. You can set this limit in YourDyno.
You need a snubber after the transformer. You can put one over the brake too. There are many types, but this one should work: https://nuwaveautomation.com/product/rcsb-snubber-network-for-solid-state-relays/. Or you could also just buy the components for the snubber and solder it together yourself. See: https://nuwaveautomation.com/wp-content/uploads/2017/12/RCSB-KIT.pdf
Note that a simple variac and a "dumb" rectifier will also work, but not with automatic brake control.
Cheers,
Jostein
Hi Jostein
I think I will use this solution : https://www.batteribyen.dk/stromforsyninger/transformere/revolta-2000w-omformer-transformer-220v-240v-til-110v-5109
With the Semikron SKPC200-110 and an SKCH28. And then use the limitation function in Yourdyno as you described.
Another question, in the Yourdyno software I can see that it i sposible to make a step / sweep test controlled with the brake. Normally these sweep tests goes from low rpm to high rpm. Is it posible to do the test from high rpm to low rpm also ? The reason is that garden tractor engines has this rpm regulator. And when used for garden pulling they start ar max rpm. And as they move down the track the rpm are slowly forced down.
Regards Henrik
Sounds good!
Yes, high to low or low to high or steady state, any curve is supported.
Cheers,
Jostein
In the case that I will need it, is it then possible to make a cycle test ? Example: 20 min at X rpm or X load. then ramp to another X rpm or X load point and stay there for X minutes. And so on for 4-5 times end then repeat the cycle for up to 20 hours! The case is that I could use this function at my work for endurance testing of some emission reduction equipment !
Regards Henrik.
Hi, yes, you can make any curve. You can also save curves and load them again.
For such a long test, it is easiest to edit the brake file. Just save a simple brake curve and you see the format. Then edit the file in a text editor and make your curve there, then read the file to YourDyno.
Hi,
Regarding the power supply. You might check out this one: https://www.ebay.com/itm/AC110-220-TO-DC-0-36V-Adjustable-Switching-power-supply-with-Digital-Display-LED/112412860433
It is a 0-36V power supply, 15A. You can use two in parallel and you have enough power for your brake. You will probably need a diode in parallel with your brake, to limit the voltage generated when you turn off the power. Let me know if you want to go this route, I can give you more details.
Cheers,
Jostein
Hi There!
I dont have the same issue, but maybe a solution for your problem.
In my case, i do have a 192VDC supply, and rewired my Telma to 192v
My problem was that under testing of ewerything, i used a Honda 300cc Mower Engine to do the work for me.
This Engine has a Maximum of 14Nm of Torque, end even with som reduction gears, only managed around 25Nm.
With the Telma able to hold 1600Nm, this gave me some issues.
I did put som Power Resistors in Series with the Retarder-windings.
My Telma CC160 has the Total Resistance of 12 ohm, with ewerything wired in series.
You may also use a SpaceHeater or whatewer you want in series, as long as its in the DC Loop.
I did try with a 60V Transformer on the AC side. But the ZeroCrossing did not like that.
Hi,
I see that the version 3.2 power supply from SportDevices http://sportdevices.com/power-supply-3.x.php supports:
- Voltage out: 50, 75, 100, 200 Vdc
So it should be suitable for many brakes. It can be controlled directly from YourDyno if you specify you want this option:
- (NEW) LINEAR INPUT: analog 0 to 5 volt
I found this website today.
I didn't understand everything so far.
I have a multi battery isolater in my hand right now. It is used in campervans military vehicles. It works with an input voltage between 6 and 50 volts and could handel 70 Amps. It works like an diode.
with that device you maybe need only one 36V 15A power supply.
Nearly the same like mine:
I have a few powersupplys 12V 30A and 24V 20A.they look nearly the same like this adjustable 0-36V 15A:
mine are able to deliver more than the printed max amps.
I use them as a battery charger. I don't know the max outpout before they get damaged. But if I charge a empty 12V starter battery the 12V supply delivers in the beginning arround 40A. That drops down to 30A after the battery rise in her voltage. I designed the length snd the diameter from the charging cables that a normal discharged 80Ah starter battery doesn't got more that 30A.
The point ist, that I think it should be no problem to use the 15A supply for two circuits each 36V.
So now for my understanding.
If the powery supply is regulated in his output voltage with a 0-5V signal and the powerysupply is able to deliver enough power for two 36V circuits, then the dyno kit is able to control the brake power from the Telma?
regards, Sebastian
Hi,
The difficulty is that the output shall be a controlled DC voltage from 0 to 24V or 0 to 192V or whatever the brake needs, so that you can control the braking force all the way from 0% to 100% and everywhere in between. There are plenty of cheap solutions that offer fixed voltage output, but not that many that give an output voltage controlled by a 0-5V input voltage.
Running the two supplies through diodes is a good idea, but probably not necessary. It depends on how the power supply is built, but it is likely that if you tie each supply's control input together so they receive the same signal, their output voltages is similar enough so the power supply will be ok.
Cheers,
Jostein