3 phase commercial fridge tripping intermittently

[buttonmoon]

Hi guys can any of you shed some light on this?

A Polish supermarket buys a large 3 phase commercial fridge with a separate compressor system like an AC system in the back. The supply comes from a 32A c type breaker which feeds another board purely for this fridge.
View attachment 14526View attachment 14527

What are the components on the bottom left and the top right? The one on the top right has three lights and a bunch of stuff written in Polish on it. The components on the bottom left both supply the compressor unit and they are both tripping at the same time as the 3 phase 32 c type on the board which supplies this board. The chap who installed all of this doesn't speak English and has returned to Poland.


My initial thoughts are that there could be a current spike when the compressor kicks in and that the c type needs to be changed for a d type and that the components on the bottom left of the board are over-current protective devices with the screwdriver adjuster and that all I need to do is adjust them up a little but I would rather be sure I understand the whole system before touching anything.

Any ideas

 

[Knobhead]

If both overloads are tripping it points to the common spupply. The 2nd picture is to small and fuzzy to make any sense of.

 

[Darkwood]

If you say a polish supermerket bought this fridge then i hazard a guess both the owners and customers are going to be able to translate any writing on it, i see the controls box is wired to a high standard nice and neat, cable markings, instructions in multiple languages.....NOT!

 

[Marvo]

i see the controls box is wired to a high standard nice and neat, cable markings, instructions in multiple languages.....NOT!

Agreed, if that is a new installation then the installer should be shot. The wiring looks appalling and I'm not surprised it's giving problems. My advice is don't quote, charge by the hour or walk away. On top of that there's a high likelihood the customer will be hesitant to pay for your repair bills if the unit has just been installed, beware you don't get caught in the middle of a warranty claim. Also if you're not familiar with refrigeration equipment and control systems I would cut and run whilst the going is good anyway.

The overload on the left will probably be for the compressor and the one to the right might be for the fan motor.

If you still want to fault find then a 32A c curve breaker should be adequate for a 3-phase compressor that's protected by a 16A manual motor starter. If you replace the MCB with a slower curved unit and the motor protection has been wound up to the 16A max you might say goodbye to the compressor motor. I would run all the usual off-line and on-line motor checks first starting with IR and checking you have 3-phases at the motor. Check for even start and run currents across the phases. It's worth remembering that the MCB is there to protect the supply cable not the compressor, the thermal overloads (manual motor starters) are there to protect the motor. If the MCB is tripping I suspect there's a problem elsewhere and refrigeration can get complicated. Starting under high head pressure, liquid slugging on the suction, under-condensing, high superheat settings, incorrect pipework sizing, short cycling due to gas leaks and even no delay on restart after defrost are problems that can all cause overload current on a compressor. Without a complete system overview it's all speculation.