11 hours ago, SomchaiDIY said:

 

i think same you because changeover motor inside is 220v and using only one phase and neutral

 

for single phase use best link all phase together because not sure which line inside circuit use for 220v control

 

 

Good thinking and all worked out well.

However.

The reasoning is incomplete.

In a 3 phase system the ATS needs to detect if any one phase is down. So the internals of the switch will be such that all inputs need to have power and if any one phase is lost the relay will be de-energised. 

On 3/13/2023 at 5:55 AM, Muhendis said:

Good thinking and all worked out well.

However.

The reasoning is incomplete.

In a 3 phase system the ATS needs to detect if any one phase is down. So the internals of the switch will be such that all inputs need to have power and if any one phase is lost the relay will be de-energised. 

in many cheap cost chinese transfer switch only the one phase line is used for control

 

this often line 1 or line a

 

the switch do not care if other phases are missing at supply

 

this is not best idea but is how many cheap 3 phase transfer switch work

 

this only problem if all 3 phase required for some machine or system  
 

4 hours ago, SomchaiDIY said:

in many cheap cost chinese transfer switch only the one phase line is used for control

 

this often line 1 or line a

 

the switch do not care if other phases are missing at supply

 

this is not best idea but is how many cheap 3 phase transfer switch work

 

this only problem if all 3 phase required for some machine or system  
 

That is scary.

How many of these deadly things have you come across.

 

"this only problem if all 3 phase required for some machine or system"

 

In my world that's the whole purpose of 3Φ. Smaller motors etc.

 

18 hours ago, Muhendis said:

That is scary.

How many of these deadly things have you come across.

 

"this only problem if all 3 phase required for some machine or system"

 

In my world that's the whole purpose of 3Φ. Smaller motors etc.

 

these cheap transfer switch have only the 2 position

missing phase transfer switch have 3 position center off

center off used when phase missing or supply fault

 

 

critical backup supply require good supply check before transfer possible 

 

here is photo for 3 position with center off and faulty power detect 

 

 

if phase loss in our factory area no big problem for us

all cnc shutdown with no volt detect 

other motor trip from thermal overload in control panel

this happen many times in the year

 

 

here is video of cheap 4 pole 2 position switch using only the 1 phase 

 

 

 

 

16 hours ago, SomchaiDIY said:

these cheap transfer switch have only the 2 position

missing phase transfer switch have 3 position center off

center off used when phase missing or supply fault

 

 

critical backup supply require good supply check before transfer possible 

 

here is photo for 3 position with center off and faulty power detect 

 

 

if phase loss in our factory area no big problem for us

all cnc shutdown with no volt detect 

other motor trip from thermal overload in control panel

this happen many times in the year

 

 

here is video of cheap 4 pole 2 position switch using only the 1 phase 

 

 

 

 

Thanks for the reminder.