Hi there
I have a customer that has acquired a 3ph Icecream Batch freezer - Carpigiani LB502
So far they have installed a 10hp Rotary Phase converter to generate 3ph from the 1ph service.
The customer wants to make sure the batch freezer is getting the right quality of hydro to make sure it works consistently. I have done a few tests and am looking for a bit of input regarding voltages. And I have included the numbers off the rating plate on the back of the machine.
The machine has 3 main components:
1. the controls (must not be connected to the generated leg)
2. 3 hp beater motor 8.4FLA
3. 3 hp compressor with water cooling 9.8FLA 78LRA
The phase converter is a Phase-a-matic PAM-1200HD with 10hp idler motor, with a disconnect switch of the generated leg back to the phase converter once the system is running (to prevent startup sequence to kick in).
The utility input is 250v split phase (125v + 125v).
The batch freezer is rated at 25a 3ph 208/230v 60hz 3 wire - max fuse size 30a.
Manufacturer suggests voltage between 215 and 218 as the best operating range.
Currently here are the voltages (line 3 is the generated leg):
No load
line 1-2: 250v
line 1-3: 237v
line 2-3: 238v
Beater motor load only:
line 1-2: 248v
line 1-3: 231v
line 2-3: 223v
Beater motor and compressor:
line 1-2: 246v
line 1-3: 225v
line 2-3: 221v
When the batch freezer is started up and running to produce ice cream the beater motor turns on first then 3 seconds later the compressor kicks in. The whole process takes about 8 minutes. After that the compressor turns off (and could/should kick back in to keep the temperature steady) with the beater still turning to dispense the icecream.
The batch freezer makes icecream just fine except that the controls that automatically sense and control the consistency of the icecream do not work as intended. If left unattended the machine will continue to freeze the icecream until the beater freezes stuck instead of cycling the compressor at a preset consistency of icecream. Therefore the operator must manually keep an eye on the progress.
I am thinking the high input voltage and difference of voltages between lines have something to do with the controls not working as intended. The machine worked perfectly in a utility 3ph environment prior to moving it to this location.
Not having too much experience with RPC as such - how do I reduce and balance the voltages over all.
1. Possibly I could reduce the 1ph input using 1 buck transformer to reduce to 215-220v BEFORE the phase converter. This would reduce the voltage of the generated leg as well!? as low as 200v under load possibly???
2. Is there a way to reduce the voltages (bucking) of the 2 utility lines only, AFTER the phase converter, leaving the generated leg as is so that the voltages are all closer to the 220-230v range?
Would this make the phases or anything go out of sync?
3. If a buck transformer were to be helpful does a 12kVA unit suffice?
4. A 3 phase buck transformer setup of all 3 lines AFTER the phase converter would reduce the voltages of each line from what I understand... defeating goal to balance voltages?
Let me know what any of you think and what my best coarse of action could be (or if I have left out any info that you might need let me know)
thanks
Fred
