power supply?????

[roonster71]

what size power supply should i use for a rutex 990h (100v 20a max)

running 3 of these servo's without blowing my drives
and wondering if i need three power supply's or one?

Continuous Stall Torque (Oz-In) 352
Peak Torque (Oz-In) 1760
Nominal Terminal Voltage (V) 120
Nominal Operating Speed (RPM) 1750

Rotor Inertia (Oz-In-s2) 0.068
Damping Constant (Oz-In/kRPM) 1.8
Thermal Resistance (C/Watt) 1.6
Maximum Armature Temperature (C) 155
Maximum Friction Torque (Oz-In) 8.0
Terminal Resistance, Nominal (Ohms) 4.3
Weight (lbs) 8.0

Torque Constant, kt (lb-In/Amp) 5.5
Back EMF Constant, ke (V/kRPM) 62
Maximum Continuous Current (A) 4.0
Maximum Peak Current (A) 20.0

thanks in advance

[ViperTX]

Yikes, check with Rutex....I'm worried about your Back EMF rating....for short durations at max rpm it will exceed the voltage rating of the FETs. I don't know if Rutex has a maximum temp. cutoff to protect the driver.

And if you're planning on running at the Terminal Voltage...you got more problems.

[roonster71]

Originally Posted by ViperTX Yikes, check with Rutex....I'm worried about your Back EMF rating....for short durations at max rpm it will exceed the voltage rating of the FETs. I don't know if Rutex has a maximum temp. cutoff to protect the driver. And if you're planning on running at the Terminal Voltage...you got more problems.

I'm not planning to run at full voltage people say these run fine on a geko with 80vdc
of couse you never know till you try it...... this is the first time ive ever used a servo untill now ive only run a stepper controller 24v 2a xylotex on a sherline mill that ive out grown maybe i should have got the servo first then the drive??? (chicken before the egg )

[rutexus]

Roonster,

I have been away for a couple of days with my boys on an international robotics meet. Back now to offer usual support.

I run very similar motors on the R990H with no troubles. I run them at 85 Vdc. This gives me a margin for different customer's line voltages. My motor terminal voltage is 140 vdc.

I use an 8 amp power supply for two axis. I think you would do fine with 12 amp.

Amveco, in Texas is my latest supplier. I pay 85.00 for a 10 amp transformer plus shipping.

I would use one common power supply for all axis (The 12 amp one). You will need the transformer, a bridge rectifier, and around 22,000 of filter caps, rated at at least 100 working vdc. Keep the filter caps within 18'' of the drive.

I have also configured a similar motor, with 26 inch lbs of torque with the R990H drives. With a 1 ohm load resistor in series with the motor, I measure 18 volts over the resistor at the instant that the motor stops. At this point the drive is turned off, and what I am seeing is the BEMF. In other words, at that point the motor is acting as a generator, and it is generating 18 amps of current (18 volts/1 ohm= 18 amps). I leave the resistor in the motor circuit, and also fuse it.

We do not notice any decrease in performance as a result of the resistor, believe it or not, and it does allow me to use a motor that is priced well, and normally in stock at Servo Dynamics.

I hope this helps.

Tom Eldredge

[roonster71]

Originally Posted by rutexus Roonster, I have been away for a couple of days with my boys on an international robotics meet. Back now to offer usual support. I run very similar motors on the R990H with no troubles. I run them at 85 Vdc. This gives me a margin for different customer's line voltages. My motor terminal voltage is 140 vdc. I use an 8 amp power supply for two axis. I think you would do fine with 12 amp. Amveco, in Texas is my latest supplier. I pay 85.00 for a 10 amp transformer plus shipping. I would use one common power supply for all axis (The 12 amp one). You will need the transformer, a bridge rectifier, and around 22,000 of filter caps, rated at at least 100 working vdc. Keep the filter caps within 18'' of the drive. I have also configured a similar motor, with 26 inch lbs of torque with the R990H drives. With a 1 ohm load resistor in series with the motor, I measure 18 volts over the resistor at the instant that the motor stops. At this point the drive is turned off, and what I am seeing is the BEMF. In other words, at that point the motor is acting as a generator, and it is generating 18 amps of current (18 volts/1 ohm= 18 amps). I leave the resistor in the motor circuit, and also fuse it. We do not notice any decrease in performance as a result of the resistor, believe it or not, and it does allow me to use a motor that is priced well, and normally in stock at Servo Dynamics. I hope this helps. Tom Eldredge

What should the ac voltage out be on the tranformer (secondary?) to make 85vdc 12amp after bridge rectifier and cap????

thanks

[2muchstuff]

Coming out of the transformer you should have 60 volts AC, (85 / 1.414= 60).

[rutexus]

Yes, the 60 volts DC is correct. Transformers are rated at a certain amperage. If you underload them, the voltage will be slightly higher than their specified rating, but not too much higher. I use a 59 VDC, 10 amp transformer at 125 vac and get 85 vdc. 60 vdc is fine.

Tom Eldredge
Rutex LLC

[roonster71]

Originally Posted by rutexus Roonster, I have been away for a couple of days with my boys on an international robotics meet. Back now to offer usual support. I run very similar motors on the R990H with no troubles. I run them at 85 Vdc. This gives me a margin for different customer's line voltages. My motor terminal voltage is 140 vdc. I use an 8 amp power supply for two axis. I think you would do fine with 12 amp. Amveco, in Texas is my latest supplier. I pay 85.00 for a 10 amp transformer plus shipping. I would use one common power supply for all axis (The 12 amp one). You will need the transformer, a bridge rectifier, and around 22,000 of filter caps, rated at at least 100 working vdc. Keep the filter caps within 18'' of the drive. I have also configured a similar motor, with 26 inch lbs of torque with the R990H drives. With a 1 ohm load resistor in series with the motor, I measure 18 volts over the resistor at the instant that the motor stops. At this point the drive is turned off, and what I am seeing is the BEMF. In other words, at that point the motor is acting as a generator, and it is generating 18 amps of current (18 volts/1 ohm= 18 amps). I leave the resistor in the motor circuit, and also fuse it. We do not notice any decrease in performance as a result of the resistor, believe it or not, and it does allow me to use a motor that is priced well, and normally in stock at Servo Dynamics. I hope this helps. Tom Eldredge

do you have the part number for the Amveco 10 amp transformer???

thanks

[rutexus]

The part number for the AMVECO transformer:

10.8 amps, 60 volts: AA5650-2030 $82.00 (typically for 2 axis of 22 inch lb motor)

13.2 amps, 60 volts: AA5790-2030 $84.00

16.7 amps, 60 volts: AA5000-2030 $98.00

They might also have some small "copper charges" like $3.00-$5.00

I realized after I got these part numbers, that AMVECO will only sell to oems and resellers.

If anyone wants me to order one for them, I'll mark it up 13% and have it drop shipped to you. I won't say I'll always do this, but I'm willing to try it.
I'll also charge modestly for the shipping.

The 13% will cover my credit card fees and administrative costs.

Tom Eldredge,
Rutex LLC

[lerman]

www.avellindberg.com has toroid transformers for excellent prices.

My 1200VA toroid transformer was about $80.

(If you talk to Melanie, tell her Ken from Newtown recommended them.)

Ken

[rutexus]

Thank you for the lead. It looks like a good one. I'll check it out!

Tom Eldredge
Rutex, LLC

[roonster71]

hi all thanks so much for the help
i order a power supply kit so every thing would come out right (i thought) well any way i got a transformer and a cap and bridge rectifier and theristor and bleed resistor but i get 70vac out of the transformer and i messure 97~100vdc at the capacitor with no load on it. is this normal and will this work? should it be mesured under a load? i dont want to fry my drives!!!


thanks
roonster