Is this transformer big enough?

[bgolash]

Hi Group
I intend to use this for my three stepper motors. I already have one power
supply in place. I`d like to eliminate the second power supply to give
me more space in the enclosure.
The two motors are 6 amps each and one is 3 amps
Could someone tell me if this transformer will produce enough amperage
to power all three motors.

0V........ 115v.........230v
BLK RED YEL
O/P:0V... 35v 0v....35v
BLK BLU GRN GRN

From a ebay auction:
You are bidding on a new 600VA toroidal transformer. It is precisely
made for high-end power amp or equipment. It has very low power loss
and magnetic leak. Labeled input 115 / 230 VAC 50/60 Hz (single coil
with center tap) and outputs 35VAC x 2 (dual coils). Mounting
hardware is included. The test results are excellent.
Voltage Test Result:
TEST CONDITION: Apply variable voltage to primary coil (115V
terminals) from 100-180VAC. No load on secondary coils.
1. Primary V = 100VAC, Primary I = .03A
2. Primary V = 110VAC, Primary I = .03A
3. Primary V = 120VAC, Primary I = .04A
4. Primary V = 130VAC, Primary I = .05A
5. Primary V = 140VAC, Primary I = .11A
6. Primary V = 150VAC, Primary I = .15A
7. Primary V = 160VAC, Primary I = .63A
Load Test Result:
TEST CONDITION: Input 120VAC 60Hz to the primary coil; parallel 2
secondary coils, 10 ohm 250W resistors as dummy load and room
temperature at 25 degree C. Temperature rises 6 degree C after an
hour test at load #5.
1. Primary I = 0.03A, Secondary V = 40.5VAC at 0.0A
2. Primary I = 1.36A, Secondary V = 39.6VAC at 3.96A
3. Primary I = 2.66A, Secondary V = 38.6VAC at 7.72A
4. Primary I = 3.92A, Secondary V = 37.9VAC at 11.37A
5. Primary I = 5.10A, Secondary V = 37.1VAC at 14.85A
Dimension – 5.0" Diameter x 2.7" High

[ViperTX]

Possibly....but need more information on the steppers...number of coils and amps per coil....

[bgolash]

This info is for two of the motors. On the Z axis I
have a small 310 oz*in Automation Direct stepper.
The details for that motor are difficult to locate.

The power supply is 51 VDC and Gecko G210

Motor Specs Bipolar

1200 oz*in

Holding Torque: oz*in 8.7

Rated Voltage 2.7

Rated Current 6.0

Resistance Ohms .45

Induction mH 5.1

[gar]

050706-2016 EST USA

bgolash:

Some comments on your transformer.

1. For a power transformer used on 115 input the primary is poorly designed because 1/2 half of the available winding space is unused. For 230 it is ok. The primary should have been two separate coils that could be connected in series for 230 or parallel for 115. But this may not be important for your application if the transformer cost is low enough.

2. This transformer was designed to have very low leakage flux at rated input voltage. This is illustrated by the no-load excitation current, and how far this nominal operating point is from saturation. Is low leakage important to you in a CNC application? I doubt it.

3. Operating at 115 or 230 there is very little core loss. Thus, most heat generated at full load is from I squared R losses.

4. At full load the internal impedance as viewed from the secondary side is (40.5 - 37.1) / 14.85 = 0.229 ohms for 115 input. If the excitation was from 230 instead, then this internal impedance should be lower. Also note the internal impedance is mostly resistive.

5. Full load efficiency is not particularly good. Note input power is approximately 120 * 5.10 = 612 watts. Output power is 37.1 * 14.85 = 551 watts. Thus efficiency is 551/612 or 90%.

6. At full load the power dissipated in the transformer is about 612 -551 = 61 watts.

7. With a full wave bridge rectifier into a capacitor input filter you can probably load this to about 0.70 * 14.85 = 10.4 amps dc load. This is a rough criteria used by Signal Transformer.

Depending upon the wire rating for temperature and the actual internal maximum hot spot temperature you might load this more.

Very difficult for you to measure internal temperature. You can can get an average internal temperature rise, this is not the hot spot, by measuring the change in resistance of the used part of the primary from a steady state value at room temperature with no load to the steady state value after full load and use the known temperature coefficient of resistance of copper to calculate the temperature rise.

This is only background information. This does not mean you should or should not use the transformer, or maybe parallel two of them.

.

[ViperTX]

Basically you're on the hariy edge....meaning it will work, but it would be nicer in you stepped to the next larger size 800 VA.