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DM860T input voltage

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shooter123456

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#1
I got a new stepper driver and I am now seeing some conflicting information about input voltage.

From the online manual, it can take 18-80 VAC or 30-110 VDC. Info on that here: https://www.omc-stepperonline.com/download/DM860T.pdf

From the manual that came with the driver, it takes 18-80 VDC or 36-110 VAC, which is flipped.

6XlSKv5.jpg

So the question is, which one is right? If it actually takes 18-80 VAC, peak voltage would be about 112 volts (peak = RMS * sqrt(2)), which makes sense. But then most residential AC supply voltage is 110V, and the DM860I, which is the same drive without the ability to take AC input, takes 20-80 VDC input. Why would they make the same one that uses a non standard AC input voltage, that is the same as its DC input voltage?

Not sure which one to trust, im hoping someone has used them before and can tell me what worked for them.
 

Nick spanners

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#2
Call the supplier, or manufacturer
Get the right answer,,,,,,,not somebody best guess
 

shooter123456

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#3
Call the supplier, or manufacturer
Get the right answer,,,,,,,not somebody best guess
I have contacted them, but they are closed until the 23rd for the Chinese new year. I was hoping someone else here might have used them before.
 

Nick spanners

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I have contacted them, but they are closed until the 23rd for the Chinese new year. I was hoping someone else here might have used them before.
Ha,,,,,,,it's never easy,
I would follow the manual that came with the machine, just check any serial numbers or product information to ensure it is the correct one........... What the worst that can happen?
A big flash, a puff of smoke and you have an amusing story for the bar
 

markba633csi

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#5
The online manual appears to be wrong. 110 volt ac (which is usually specified average not peak to peak which would be about 160v) rectified would be about 80 volt dc filtered
The drive obviously has an internal bridge rectifier so you can input a higher ac or a lower dc value. That's how I see it but you should verify.
Mark
 

JimDawson

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#6
In Asia, 110V, 50 Hz is the norm, in North America, 120 V ( and normally a bit higher), 60 Hz is the norm. 60-100 VDC is common in CNC equipment.

The easy way would be to use a 240/120 power transformer and feed the 240V side with 120V, that will give you a 60 VAC output, or about 85VDC internal in the drive.
 

markba633csi

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#7
No when you rectifiy ac you are effectively dividing it in half (roughly) in terms of the peak to peak values so the dc value will always be less
Mark
 

shooter123456

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Ha,,,,,,,it's never easy,
I would follow the manual that came with the machine, just check any serial numbers or product information to ensure it is the correct one........... What the worst that can happen?
A big flash, a puff of smoke and you have an amusing story for the bar
It never is... It was purchased from Amazon, so if I get the puff of smoke, I can return it as defective since the manual specifies it can handle 110 VAC. Thank you for your input.
 

shooter123456

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#9
The online manual appears to be wrong. 110 volt ac (which is usually specified average not peak to peak which would be about 160v) rectified would be about 80 volt dc filtered
The drive obviously has an internal bridge rectifier so you can input a higher ac or a lower dc value. That's how I see it but you should verify.
Mark
Thank you. I thought it made more sense for the 110v to be AC, and the manual says the mosfets can handle 160v. Its looking more and more like the printed manual I received is correct.
 

JimDawson

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#10
No when you rectifiy ac you are effectively dividing it in half (roughly) in terms of the peak to peak values so the dc value will always be less
Mark
Sorry Mark, you have that backwards.

DC Volts = AC Volts x 1.414
so 100vac x 1.414 = 141.4vdc
or 120vac X 1.414 = 169.7vdc
 

markba633csi

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#11
120 x 1.414 = 169.7 yes BUT that's peak to peak. When you rectifiy that you effectively divide it in half but then you have twice as many half cycles per unit time, so it comes out to a little less than the initial ac value.
That's why most dc motors are rated at 90 volts to be run from a 120 volt ac line.
 

JimDawson

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#12
120 x 1.414 = 169.7 yes BUT that's peak to peak. When you rectifiy that you effectively divide it in half but then you have twice as many half cycles per unit time, so it comes out to a little less than the initial ac value.
That's why most dc motors are rated at 90 volts to be run from a 120 volt ac line.
For 1/2 wave rectification that would be true since you are only using 1/2 of the AC cycle as the output. In motor circuits, this is only used for DC motor controllers.
1518543351758.png


Full wave rectification would give you ~ 169 VDC output max, but more like ~140VDC useful output.

1518543677772.png
 

markba633csi

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#13
Hmm It's been a while since I studied this stuff- something still looks odd to me though- I shall return
Mark
ps dc motor controllers (of the twin diode, twin scr type) are full wave not half- I'm certain
 
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markba633csi

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#14
Ah I see where I goofed up, it's actually 338-340v peak to peak. So (according to wiki) dividing by pi gives about 108v average dc, without filtering.
So my original point is still valid, that the effective dc you end up with is just a little less than the average ac value you started with (120)
meaning the printed manual is the correct one
Mark
 
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ccomito1223

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#15
I realize this post is somewhat old but I too am going through the same thing. Did you ever get this worked out? It's looking like I can use AC from the wall output but I didn't want to risk it. How did you end up making your input voltage connection?
 

shooter123456

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#16
I realize this post is somewhat old but I too am going through the same thing. Did you ever get this worked out? It's looking like I can use AC from the wall output but I didn't want to risk it. How did you end up making your input voltage connection?
I ended up sticking with the 48v DC power supply. I would have preferred to go with AC power, but I didn't want to risk blowing the drive.
 

ccomito1223

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#17
I ended up sticking with the 48v DC power supply. I would have preferred to go with AC power, but I didn't want to risk blowing the drive.
I was worried you might say that :) I also have a 48V DC supply but would prefer to go with AC and do away with the supply all together. Thanks for the input though. I did email the manufacturer. I'm not sure if I'll get a response but if I do I'll post back here for future reference.
 

RJSakowski

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#19
AC voltages are usually expressed as RMS which is the voltage that would give you the same power as a DC voltage of that value. Peak voltage is 1.414 times that and peak to peak voltage is twice that or 2.818.

When AC voltage is rectified, either with a half wave rec6tifier or a full wave rectifier, the peak DC voltage is 1.414 times the AC RMS voltage, providing there is no load. If there is a filter capacitor in the circuit, the capacitor will charge to the peak voltage, again with no load. As a load is applied, the output voltage will drop with increasing load. In real circuits, the DC output voltage is usually somewhere between the RMS and the peak voltage.

As for the OP's original question, it appears the 80 volts is a safe maximum voltage in either case. If I was concerned about doing damage, I would limit the voltage to that value until I had a definitive answer.
 

ccomito1223

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#20
So to say the same thing in a way I understand it is, AC is measured in Vrms. When AC is rectified and filtered, the supply will charge up to the peak value (Peak=RMS*1.414). So if you take your 80V AC X 1.414 you get 113V DC or 113V DC X .707 = 80V AC. So,,, no you can’t use 120V AC rms, that will be 170V DC after rectifying and filtering. The short answer is this driver needs an 80V AC transformer, or a 110V DC power supply.
Thanks @RJSakowski, @JimDawson and @shooter123456 ..
 

RJSakowski

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#21
I would suspect that the driver was designed for dual input, either AC or DC. DC would directly power the driver and AC would be converted to DC to power the driver. Modern power supplies are not simple rectifier/capacitor filter supplies but usually incorporate some sort of voltage regulation to provide a constant voltage output under varying load requirements.

Stepper motors have a theoretical infinite torque at zero rpm. In practice, however, the torque is limited by the resistance of the motor windings. Generally speaking, a stepper operates better on a higher drive voltage than a lower voltage. Providing a working range for the input voltage allows the driver to be used with different motors and with different degrees of effectiveness.

You have two conflicting specifications for the input voltage, either AC or DC. Using the lower of the maximum voltage specifications will ensure that you don't overdrive your input.

In viewing the online manual, you have a photograph of the driver with voltages specified as well as a text spec sheet. If your driver matches the photograph in the manual, I would tend to believe that before I would the printed manual. Also, in my experience, on-line manuals tend to be more up to date than the printed versions.

Text within the manual states that the output drivers are rated at 160 volts (page 6). It further states that it is recommended to limit an AC supply to 70 volts to allow for voltage fluctuations and back EMF. That sounds like good advice to me.
 
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