1ph or 3ph VFD selection 1

[kallileo]

I have a small agitation motor with the following charateristics:

230/400V 3ph50Hz 0.42/0.24A 100RPM Input Power 0,14W

It will be used to agitate condensed milk in a vertical 400l tank.
I will use a Schneider VFD to control the speed between 30-100RPM.
The single phase ATV12 mode is 50% cheaper than the 3phase ATV321.
What will be the disadvanges of using a single phase 230V VFD with output 3x230V instead of a 3ph 3x400V?
Could this cause any problems?

 

[waross]

In larger sizes the disadvantage is 1.73 greater current and larger conductors.
At 0.42 Amps there may not be any disadvantage.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[electricuwe]

If you operate 100's of such small drives as single phase units in a plant, you will suffer from harmonics a lot more than with three-phase drives. If there are only a few, this is no concern.

 

[jraef]

One drive is 230V, the other drive is 400V, that alone accounts for most of the price difference, not the 1 phase or 3 phase. If you can use either voltage on that motor, the 1 phase input is fine.


"Will work for salami"

 

[waross]

Also, three phase drives may not be available in that small size.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[kallileo]

Thanks for the input.
There will be only one unit as this tank will be installed in a bakery.
It's a nano size 1ph drive and it's easier to fit into the electrical panel of the tank than the 3ph model.

Since it not going to have any influence the output torque negatively, I'm going with the 1ph 230V model.
What about electrical box and the cables? Should I use any special type like shielded cables?

 

[ozmosis]

Follow the instruction provided by Schneider for installation instructions (cables and wiring advice) but, as it is a bakery and possibly on equipment that is portable, check that your VFD will not be tripping out any ground fault circuit breaker (GFCI in N.America or RCD in Europe/ROW). Leakage current from the drive or EMC filter if fitted, will often pull out these breakers as it is typically >30mA. If your installation already has GFCI/RCD, chances are it is not designed for VFD use that needs to monitor for the additional DC components in the waveform. These will either not be seen by the GFCI/RCD (dangerous) or keep tripping it (annoying) along with the higher leakage current you get from a VFD.
It may not be a problem but worth checking as, what appears to be a lower cost solution, may turn out more expensive if not done correctly, and I don't just mean the $'s.

 

[jraef]

Also, being that this is a bakery, small "inexpensive" drives like that one, and ESPECIALLY that one, need serious de-rating for temperature, meaning the INTERNAL temperature of the box you put it in. All drives give off heat. If you seal the box to protect it from dust and/or hose down during cleaning cycles, the heat cannot dissipate fast enough so it cooks itself. You can compensate by increasing the surface area of the box to radiate internal heat, but that can then work against you if you get anywhere near an oven. You may want to consider de-rating it prophylactically.


"Will work for salami"

 

[itsmoked]

Re jraef's point: Mount it as low as possible in the enclosure as the temperature it will see is a direct function of its mounting height.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[kallileo]

Eventually the motor will be 0,26kW and the drive ATCV2 0,37kW.

http://www.inverterdrive.com/group/AC-Inverter-Drives-230V/Schneider-ATV12H037M2/

The drive has integrated EMC and a heat-sink but without a fan.
I'm thinking on putting air vents on the box with some dust filters.
According to drive specifications the ambient operation temperature is as follows:

-10...40 °C with protective cover from the top of the drive removed,
40...60 °C with current de-rating 2.2 % per °C

Along with the drive inside the box I will have a circuit breaker and the contactor of tank's compressor.
The box will be probably mounted on cooling unit and located near the compressor.
Is there any actual difference between plastic and metal boxes?

@ozmosis
I will have the RCD check in mind.

 

[waross]

Will you have a control transformer for the contactor? If you will use a transformer consider a large enough transformer to run the VFD also. That will add to the heating issue but will go a long way towards mitigating GFI/RCD issues. I would consider a small transformer with a weather proof case, mounted and spaced on the outside of the control cabinet.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[electricuwe]

Kallileo,

in response to you last post please note the follwing: removing heat by natural convection (no fan) will not work through filters. Your choices for an appropriate thermal design are as follows:

- natural concection inside a quite large enclosure, heat conduction through the wall, natural convection from ouside enclosure to ambient
- small enclosure with fan and filter (not really recommended, because such filters are usually not replaced/cleaned as needed)
- choose a drive that provides suitable ingress protection by it's own enclosure (best option from my point of view)

 

[kallileo]

I will not have any extra transformers.
What does exactly the following means in the specifications?
"Heat Loss at max output: 27W."

 

[jraef]

That means when the drive is running the motor at full capacity, in this case .37kW, the drive itself will reject 27W of energy into it's environment. So if you have it in an enclosure, that heat gets trapped inside and must be accommodated either by ventilation or radiating through the side walls of the enclosure.


"Will work for salami"

 

[kallileo]

Does the drive provide thermal current overload protection or should a external device to be used?

 

[itsmoked]

Drives do provide thermal protection. (I haven't waded thru this whole thread to see if something odd is contemplated.)

Keith Cress
kcress -

http://www.flaminsystems.com