G540 + EMC2 = missing steps

would it be okay if I change my power supply to 350 watt from 125. ( I am using xylotex (3) 269 oz stepper @ 2.8amp each.

Fredasiong wrote: would it be okay if I change my power supply to 350 watt from 125. ( I am using xylotex (3) 269 oz stepper @ 2.8amp each.

If you are running at 24V then 125W is only 1.7A per motor. If you are running at a higher voltage than that, then you have even less current.

350W is enough for your motors if you are running at less than 40V.

Arceye,

I found a power supply at 24v @ 15A 350 watt which will give me 5 amp supply per motor. In my case the stepper only draws 2.8 max. ea.

Thanks for your help. Hoping that this will solve my problem.

would it be okay if I change my power supply to 350 watt from 125. ( I am using xylotex (3) 269 oz stepper @ 2.8amp each.

I didn't know they made PSUs that small :laugh:

I found a power supply at 24v @ 15A 350 watt which will give me 5 amp supply per motor. In my case the stepper only draws 2.8 max. ea.

You should certainly see an improvement, just make sure you keep your velocity and acceleration figures reasonable, they are still pretty small steppers after all

regards

Stepper coil current is not even remotely equal to power supply current. The stepper coil acts as a 'current storage'; it is charged to X amps and then only the losses (iron losses, copper losses, mechanical work done) have to be replenished. That does not take X amps times V volts, but only a fraction.
To make it even worse: when the current in the coil must rise power is drawn from the supply. When the current must fall, that energy is partially returned to the power supply.

It is this mechanism, together with the energy generated when the motor is decelerated, that causes so much trouble for switchmode power supplies. A normal supply is designed to supply power, not to absorb it. Of course they can be designed to cope with this situation, but almost noboby does that. Adding a large capacitor helps too, but all to often the PSU sees this as a short during startup and goes in overload protection. Grossly overdimensioning the PSU so it sees the load imposed by the stepper drives more as a nuisance than as work helps too.
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On average a toroid, bridge rectifier and large capacitor is a far better power supply for motors that accelerate/decelerate much.

How much power do you really need? I have never seen more than 180 Watts going into 3x 4Nm NEMA34 motors fed from 75V running torture G-code which exercises all axes.
With NEMA23 ones and lower supply voltages it would be hard to pump 35 Watts into a single motor.

DaBit wrote: Stepper coil current is not even remotely equal to power supply current. The stepper coil acts as a 'current storage'; it is charged to X amps and then only the losses (iron losses, copper losses, mechanical work done) have to be replenished. That does not take X amps times V volts, but only a fraction.

I think that you premise is wrong but your conclusion may be correct.

The current through the phase will be the current set by the stepper driver. That is it's job. However the voltage applied will be much lower than supply voltage in the steady-state so the power will be less.
In practice the current is limited by the drive PWM, rather than an actual voltage reduction, so it is the full V * I but only for a small fraction of the time.
At full-speed the duty cycle will increase, but I am not clear on if it gets to 100% of time-on at the same time as 100% of back-emf voltage and 100% rated current.

Interesting data-point about your setup, though. How (and where) is your power consumption measured?