1PH to 3PH converter

[Timberline]

Hi all hoping someone may be able to help!
We have purchased an articulated trailor previously used for document retrieval, they were apparently water damaged and the trailor is food grade and fitted with two blast quality freezer units ( 415 3 Phase ). the documents would be quickly frozen for repair later!!
We are converting it to use as an on farm butchery, however we have no mains electric on site let alone a 3 phase 415 supply. We have run a 240 supply to the unit from our 6kw inverters run via a large battery bank/Lister petter setup.
We would like to utilize the existing freezer units which look in very good/new condition rather than have the expense of purchasing walk in 240v cold rooms.
I am having trouble evaluating the HP/ Kw rating of the units so that we could contemplate purchasing a 240/415 converter of adequate rating to run either one or two of the units.
The compressors are Bristol H73A423 DBEA, I have no refrigeration expertise at all, and if further information is required please ask.

Regards Steve

[Brian_UK]

That compressor, H73A423, has a run current of 5.8amps and a locked rotor current of 39amps. There will additional loads for the condenser fan and the evaporator fan(s).

If you visit the Bristol website...

http://www.bristolcompressors.com/

click on Bristol Recips and you will get a list on the recip compressors; scroll down through the list, or search your screen, to find your model, click on that to find the technical literature.

:off topic: Timberline - Dorset, mmmmm, anywhere near Dorchester ?

[Electrocoolman]

Hi Steve,

The compressor details that you quoted appear to have an electrical rating of around 3 to 3.3kW. with a running current of 5.8A.

I don't think that your inverter would be able to stand the DOL start surge from these compressors (39A LRA).

The problems that you have are not insurmountable though.....
I would look at using a Variable Speed Drive (VSD).
1). These provide a slow speed controlled start up, thereby limiting the current demand.
2). The compressor is designed for DOL only and you only have access to three terminal connections (ie 415v only) with no possibility of change to lower voltage.
3). A VSD will take care of the 3 phase conversion.
4). To drive a 415v motor you will need to supply the VSD with 400v, but not necessarily 400/3 phase.

So as I see it, you will need to step your 240v up to 400v with a transformer, feed this to the VSD input.
You should be able to set the VSD to ignore the phase sequence input logic (you are only feeding it with 1 phase not 3).
The VSD only feeds the compressor and possibly the fans if they are also 3 phase. VSD set for 50Hz output. Your control system will have to be modified to accomodate VSD.

I think you might need to use at least a 4kW rated VSD.

Hope this gives you 'food for thought' !