[Dave2024]

Hi was wondering if anyone can confirm that my logic is good before I power up for the first time? I just received a new StepperOnline T6 series 1kw servo drive and motor kit. In the video they show someone one powering it using a 24v power supply for testing but the manual says its rated for 220v single phase. What I'm hoping what I can do is power it directly from a 120v wall outlet. Is this ok to do this and what's the draw back of using 120v instead of the rated 220v? Also does it matter what the order is on the neutral an hot leads go on the drive? In the manual all it shows is an L1 and L2 then on the bottom is a ground? Thanks

[joeavaerage]

Hi,
I use Delta servos which are very similar.

You hook the incoming AC to L₁ and L₂. The polarity does not matter.

My Delta drives and I suspect your also will require a line level AC supply that powers the DC signalling side of the servo, in which case L₁ and L₂ will be paralleled
to these inputs.

My line level AC here in New Zealand is 240VAC and I can hook direct to my drives.....they are rated to 255VAC input. I rather suspect if I tried 120VAC they would still work but I think they would not have the top
speed that I would expect.

Certainly do not think there is any harm in trying 120VAC. If it does not work or you get Low Voltage alarms then you'll have to supply 220VAC...end of story.

Craig

[Dave2024]

Ok thanks, I tried 120v and the drive did not work. Went and built a sketchy dual circuit outlet adapter to get 220v and it started rite up. Left the ground disconnected though because I don't have qualifications of an electrician and 220v scares me that I wont ever have the chance to explain what making a mistake is like with it. Anyways these drives only work when powered to specification. Thanks

[joeavaerage]

Hi,
the incoming AC voltage is rectified and smoothed by DCLink capacitors.

If you apply 120VAC the peak voltage is 120 x 1.41 =136.9V. This is what is stored and used by the drive to power the motor, if you like it uses smart electronics to 'chop up' and switch that 136.9VDC
into AC of variable frequency, voltage and phase to suit the servo motor.

If you apply 230VAC the peak voltage is 230 x 1.41=324.3V. This is what is stored and used by the drive.

136.9V is pretty anemic by comparison to 324.3V.

There are power supplies that can 'boost' the voltage. For instance while the peak voltage of a 230VAC input rectified/smoothed supply is 324.3VDC a boost regulator can push that up to 400VDC and higher. It uses a current switching
boost inductor, and very clever it is too. Using a circuit like this would allow you to power a device for which your regular AC line is not enough.

The downside is the extra cost and complexity. Such boost circuits tend to be used for either low power (say 50W or less) supplies where the extra cost is small, OR in high power circuits for which such a boost is absolutely required
irrespective of the cost.

Interestingly all PC power supplies are of the 'boost' type. This is done for power factor correction, and is mandatory in the US.....and is therefore an effective world wide standard. The incoming line voltage, anywhere from 100VAC to
250VAC is rectified, boosted and smoothed to 400VDC. From that 400VDC various buck regulators break it down into 3V, 5V, 12V etc required for the PC. By using a boost circuit means that the device can operate of a very VERY wide range
of line voltages, a very useful feature indeed allowing the device to be operated in nearly all countries.

I would not expect entry level servo drives to utilise this boost technology, despite the potential advantages it can offer, it just costs that much more. Therefore it is not surprising that your servo drive will not operate when supplied with such a low
input voltage. It expects 220VAC....the damn well give it 220VAC. I believe those StepperOnline servos are a bit tender at higher voltages. Over 230VAC they tend to fail. My Delta servos handle 255VAC, which is probably just as well because here in
New Zealand the normal and natural single phase line voltage is 243VAC. I'd have to use an autotransformer or something to use the StepperOnline units, whereas I can just hook the Delta's direct to the line.

Craig