Connecting a single phase control panel to a 3 phase power supply

[Sean_SA]

Hi guys

This question is perhaps for the electric brewing gurus out there.

I have a small brewery that has just started up. My brewing system is a 50A single phase system, running two 5500w elements at a time. Control panel is wired for single phase. I am based in South Africa and we run on 230v single phase

My brewery is based in a small village shopping centre and the shopping centre electrician made quite a significant stuff up. The shopping centre runs on 3 phase 415V. I requested an 80A single phase power supply to my brewery so the guy set my DB board accordingly with the correct breakers etc. except the main power supply cable coming in is rated at 40A, which is connected to a 40A 3 phase breaker further down the line. I have no idea how he did not realise this but he went ahead anyway and apparently did not realise it. Fortunately I did.

My question is the following... If I can bring a 40A 3 phase power supply into the brewery and make my DB board 3 phase. Would I be able to hook up my single phase 50A control panel to it and be okay? As far as I am aware 3 phase uses less current in relation to wattage versus single phase but as the panel is single phase I don't know if it'll make a difference and will still use the 50A, ultimately tripping the 40A 3 phase breaker anyway.

Appreciate any advice given on the matter

 

[whoaru99]

If your control system runs two 5500W heaters from a single phase that is >40A @ 230-240V.

Having three-phase available is immaterial if all that load is on one leg/phase; ~45A load on a 40A circuit doesn't work too well.

 

[bruce_the_loon]

Hi Sean,

You can switch the system over to three phase with 6kW three phase elements which draw 10A per phase. This will require changing the elements in your vessels, rigging your DB for three phase and changing the control panel to switch three phase to the elements. This will require swapping out the single phase SSRs with three phase SSRs rated for the load and probably any isolators and switches in the panel with all the costs associated with that.

If the capacity for 80A single phase is available on the center DB, then the cost would be the new cable, an 80A breaker for the upstream DB and the labour to install.