Fiac v10 airblock 3 phase wiring

[James87]

As above, come across some very odd coloured wiring for our 3 phase compressor. Anyone have any ideas on l1, l2 and l3?

Earth is green+yellow

No neutral

The rest are black, brown and blue

Motor is 10hp

 

[mtt.tr]

Just wire in on the 3phases, if it spins in the wrong rotation swap over 2 phases

 

[James87]

Just wire in on the 3phases, if it spins in the wrong rotation swap over 2 phases

Wired it

(BrownL1,BlackL2,BlueL3) and it ran in reverse, which 2 phases would I need to swap? Unsure weather it's star or delta either, or if that even makes a difference

 

[daleyd]

Wired it

(BrownL1,BlackL2,BlueL3) and it ran in reverse, which 2 phases would I need to swap? Unsure weather it's star or delta either, or if that even makes a difference

Swap any 2 phases, it doesn’t matter which ones .

 

[James87]

Swap any 2 phases, it doesn’t matter which ones .

Thanks, will give it a try in the am

 

[AKN]

As it is 3wire without a neutral it is delta.

 

[daleyd]

As it is 3wire without a neutral it is delta.

No 3 phase motors require a neutral - it’s 10hp so it may well be star/delta for starting

 

[AKN]

No 3 phase motors require a neutral - it’s 10hp so it may well be star/delta for starting

It ran without a neutral connection, makes it delta!

 

[daleyd]

No it doesn’t - you can have a star/delta starting arrangement with no neutral.

I’ve never known a 3 phase motor to need a neutral, whether connected in star or delta.

It probably is connected in delta if a big 3 phase motor (400/600 v) but quite a few smaller motors for 230/400v operation will need to be connected in star for 400v operation - but they still won’t need a neutral.

 

[AKN]

From the system perspective if there is no neutral it is a delta connected load as there can be no neutral current.

 

[daleyd]

From the system perspective if there is no neutral it is a delta connected load as there can be no neutral current.

I fear you are confusing a transformer connection and a motor connection. Just for clarity - a 3 phase motor whether star or delta does NOT need a neutral so the lack of neutral is no way to identify how the motor should be connected - you can only determine that from the data plate and supply voltage.

 

[mtt.tr]

From the system perspective if there is no neutral it is a delta connected load as there can be no neutral current.

3phase balanced loads do not have a neutral

 

[Hood]

 

[AKN]

3phase balanced loads do not have a neutral

3phase balanced loads have no neutral current whether they have a neutral connection or not is irrelevant. Just removing a neutral will not magically balance a load.

 

[mtt.tr]

3phase balanced loads have no neutral current whether they have a neutral connection or not is irrelevant. Just removing a neutral will not magically balance a load.

But a motor is a balanced load hence no requirement for a neutral.

Most 3phase kit has no neutral instead they will have a transformer for anything needing single phase as typically it's low current stuff

 

[daleyd]

3phase balanced loads have no neutral current whether they have a neutral connection or not is irrelevant. Just removing a neutral will not magically balance a load.

Probably easier if you show us a picture of a 3 phase motor with a neutral connection…I’ve never seen one but am happy to be corrected.

 

[AKN]

Probably easier if you show us a picture of a 3 phase motor with a neutral connection…I’ve never seen one but am happy to be corrected.

In aircraft where neutral point of both generator and motor are taken to the airframe, less so in modern designs as most are now run from motor drive electronics.

 

[mtt.tr]

In aircraft where neutral point of both generator and motor are taken to the airframe, less so in modern designs as most are now run from motor drive electronics.

We are discussing 3 phase induction motors here.

 

[AKN]

View attachment 336046

In your ”star“ internal configuration if there is a shorted winding where do the fault currents flow?

 

[daleyd]

In aircraft where neutral point of both generator and motor are taken to the airframe, less so in modern designs as most are now run from motor drive electronics.

I’m guessing the OP doesn’t have one of those on his compressor