Soft starter

[Shinekhuu]

I want to size a soft starter to following freezer. 

Single phase, 660W, 110V

Starting current 45A

I was wondering if I can use 25A single phase ATS01 starter.

Soft starter:https://www.se.com/jp/ja/product/ATS01N125FT/ats01-%E3%82%BD%E3%83%95%E3%83%88%E3%82%B9%E3%82%BF%E3%...

Main source is single phase 110V and 30A. Please help.

[Bastian_Schmitz]

Hi,

The choosen soft starter is a 3 phase model. So far I understand you has an 1 phase freezer. In that case I would suggest to use a 1 phase model like ATS01N106FT. 

The starting current of the compressor is in my opinion not the correct value to select the soft starter. Because this one should be reduced through the soft starter.  

Alternative you could also the next bigger one to have more safety.

But in any case im not 100% sure that the compressor of the freeezer will start in any case. Normally the compressors in freezers in 1 phase with capacitor are weak from the starting torque. The use of the softstarter will reduce the torque. This could be a problem, but it could also work. It is hard to say from distance.

[otrotabi]

One way to minimize the needed torque is to equalize low pressure side with high pressure side (on the refrigeration circuit itself). If it is a standard commercial freezer there´s usually a capillary tube before the evaporator and all you need to do is to allow enough time  and it will equalize by itself. But if there´s a TXV valve (or a liquid solenoid valve which would be rare on a small freezer) you would probably need to make sure the circuit is not unbalanced when trying to start it. Some people use a bypass solenoid for the TXV which is off once the compressor starts.

The kind of compressors used in refrigeration for small freezers generally have an internal bi-metal overload which means that if the motor does not start the circuit opens thus protecting the motor. 

[BrownSugar]

Thank you for your request. I believe the ATS01N125FT is not suitable for this application. The freezer motor is 660 W, 110 V, single-phase, with a running current of about 6 A but a starting current of 45 A. The ATS01N125FT is rated for 25 A nominal, and that rating applies to steady-state current. It cannot handle a 45 A inrush without tripping or overheating. In addition, the ATS01 is a voltage ramp soft starter with a short ramp time of 1–5 seconds and no true current limit. For a heavy start, the current will still spike close to direct-on-line levels. 
The recommended solution is to replace the single-phase motor with a three-phase motor and use an Altivar drive. This allows a long acceleration time of 20–30 seconds or more and provides current limit to protect fuses and the transformer.